1955-1962 E.F. Johnson "Viking Valiant" 
AM/CW Transmitter

This page chronicles repairs made to an E.F. Johnson "Viking Valiant" AM/CW Transmitter.
Latest revisions are at the bottom of the page.


1955-1962 E.F. Johnson "Viking Valiant" (Serial Number 28819)
AM/CW Transmitter (160 to 10 meters)


On Friday evening, November 2, 2007 I attended the annual RARA (Rochester Amateur Radio Association) auction to bid on this circa 1955-1962 E.F. Johnson "Viking Valiant" AM/CW transmitter. After making several must-have bids, I finally got it for $325, thus adding "AM mode" to the ham shack in a hefty (83 lbs.), retro style.

The plan was to use it with a 1946 Hallicrafters S-40 receiver, but I still needed an antenna relay (a.k.a. "Dow Key Relay", or "T/R switch") to toggle the antenna between the transmitter and receiver. As a result of some fast networking, an Alliance T/R switch was sourced.

I originally considered the less powerful (but aesthetically pleasing) Johnson "Viking Ranger" transmitter but was persuaded by a couple of AM veterans (including K2MP) that the extra punch of the Valiant would come in handy to break those DX pileups down into Pennsylvania and even out to Maine (hi hi).

November 7, 2007 / RARA auctioneer and historian, Ed (K2MP) with the ex-K2JD Viking Valiant.
The radio on top is a Yaesu FTDX-400. Photo courtesy: Len (KC2PCD).

The Valiant has three Type 6146 output tubes modulated by two Type 6146 tubes.

This Valiant transmitter was originally part of the RARA club station (K2JD) located at 111 Westfall Road. Auctioneer and historian, Ed Gable had this to say about the radio's history: "The set was purchased by the County of Monroe (New York) for RACES (Radio Amateur Civil Emergency Service) in the mid 1960s. The Radio Officer was Charles "Chuck" Brelsford (K2WW) 1. The Valiant was used as the NCS (Net Control Station) on the NY Counties 75 meter CD (Civil Defense) Net. It was first used in the radio room in the basement of the County Hospital at the corner of Westfall Road and East Henrietta Road."

There were two crystals in the radio when I got it home from the auction. A Type FT-243 (3745 kc), and a Type HC6 (3730 kc). I subsequently (15-jan-2008) got a Type FT-243 (3837 kc) for use on the AWA AM Net. The FT-243 3837 crystal came from Brian (AF4K/SK).

Specification Overview

Serial number: 28819
Type or Cat number: 240-104

This particular "Viking Valiant" was Factory-wired, as verified by the rivets at the back of the cabinet.

Modes: AM/CW
Bands: 160 - 10 meters
Input Power: 200 watts (AM), 275 watts (CW)
VFO: Internal
Power Supply: Internal
Final Tubes: ( 3 ) 6146 parallel
Modulator: ( 2 ) 6146 push-pull
New Price: $349.50 (kit) / $439.50 (wired)
Years Produced: 1955-62
Size: 11 5/8" high x 21 1/8" wide x 17 3/8" deep
Weight: 83 lbs.

Schematics and Manuals


Pilot Lamps (VFO dial, power, etc.)

To replace the pilot lamps, it was necessary to remove four long, 14" (actually: 13 13/16") 10-24 round-head bolts and star washers from the rear of the cabinet. Also removed twenty short (", 10-24, round-head) bolts at the back of the cabinet. Slid the chassis out the front of the cabinet to gain access to all pilot lamps (bulbs).

Notes: (parts / repairs / manuals, etc.)

Most of these links were used to gather information about the transmitter before work began in earnest.

RF Dummy Load

To "tune up the finals" without sending the signal over the air, an "RF dummy load" (50 Ω impedance) should be used. Originally, the "paint can" style wet dummy loads (reference: Heathkit Cantenna HN-31) were filled with transformer oil (dielectric oil). In the 1960s, transformer oil contained PCBs (polychlorinated biphenyls). Most PCBs were manufactured as cooling and insulating fluids for industrial transformers and capacitors. PCB production was banned in the 1970s due to their high toxicity.

Heathkit Cantenna model HN-31

In lieu of transformer oil, mineral oil could be used. The only difference is when the dummy load is being used at maximum power ratings. The transformer oil will keep the load cool for a longer period of time than the mineral oil. Figure about 50% less time at maximum ratings. Reference the power dissipation derating curve on the side of the Cantenna for details.

Table 1
Valve ( tube ) line-up for E.F. Johnson Viking Valiant ( 21 valves total ):

Replacement prices per Vendor X as of November 11, 2007
Note: red text = test and/or replace tube due to reduced output power (90 watts). See: Johnson Matchbox tuner SWR meter reading on main page.

Tube Schematic Ref. Nr. Type Reference Price
6AU6 V1 Variable Frequency Oscillator (VFO) www.r-type.org/exhib/aam0057.htm x
0A2 V2 VFO Screen Voltage Regulator www.r-type.org/exhib/aaa0696.htm x
6CL6 V3 Crystal Oscillator / VFO Isolator www.r-type.org/exhib/aaa0039.htm x
5763 V4 RF Multiplier/Driver www.r-type.org/exhib/aam0048.htm x
6146 V5 Parallel Final Amplifier www.r-type.org/exhib/aaa0546.htm x
6146 V6 Parallel Final Amplifier www.r-type.org/exhib/aaa0546.htm x
6146 V7 Parallel Final Amplifier www.r-type.org/exhib/aaa0546.htm x
6AQ5 V8 Clamper www.r-type.org/exhib/aaa0874.htm x
0C3/VR-105 V9 Screen Voltage Regulator www.r-type.org/exhib/aam0002.htm x
0C3/VR-105 V10 Screen Voltage Regulator www.r-type.org/exhib/aam0002.htm x
12AU7 V11 Time Sequence Keyer www.r-type.org/exhib/aam0051.htm x
12AX7 V12 Cascade Speech Audio Amplifier www.r-type.org/exhib/aam0038.htm x
6AL5 V13 Audio Clipper www.r-type.org/exhib/aaa0873.htm x
6C4 V14 Third Audio Amplifier www.r-type.org/exhib/aam0043.htm x
12AU7 V15 Parallel Audio Driver www.r-type.org/exhib/aam0051.htm x
6146 V16 Push-Pull Class AB2 Audio Modulator www.r-type.org/exhib/aaa0546.htm x
6146 V17 Push-Pull Class AB2 Audio Modulator www.r-type.org/exhib/aaa0546.htm x
866A V18 Mercury Vapor H.V. (660 v) Rectifier (power transformer T1) www.r-type.org/exhib/aab0018.htm x
866A V19 Mercury Vapor H.V. (660 v) Rectifier (power transformer T1) www.r-type.org/exhib/aab0018.htm x
5V4G V20 Low Voltage Power Supply (T2) Rectifier www.r-type.org/exhib/aaa0597.htm x
6BY5GA V21 Bias Rectifier (-265 volts)   x

Repair History

November 3, 2007 (Saturday):
Cleaned the exterior and removed some old masking tape, scotch tape, tuning notes (typewritten) and a CD (Civil Defense) decal. The decal was peeling off anyway. It said, "Monroe County" at the top, and had the CD logo in the center and said, "New York" at the bottom. It had another decal which read, "9332", "Property of County of Monroe." This certainly was part of the history and patina of the radio, but my feeling was that whomever applied those decals 40 years earlier, did so with a legitimate purpose, but essentially defaced the original appearance of the radio.

November 5, 2007 (Monday):
The public library did not have the manual for this transmitter. So, I purchased a re-print of the Viking Valiant manual from eBay. Price was $11.95 plus $6.00 shipping. The vendor's description of manual was,

"Reproduction of the factory Operation Instruction (service) manual for the E.F. Johnson Viking Valiant amateur radio transmitter. This transmitter was a very nice performer on 160-10 meters, using three 6146s for the final output amplifier. It ran 275 watts on CW, 200 on AM phone. The Valiant was renowned for its stable built-in VFO, TVI suppression, its powerful signal, and its splendid sharp audio quality on AM. Includes pertinent diagrams and/or photos, installation and connections, operating instructions for all controls, a complete parts list, tube placement chart, easily readable schematic diagram to identify all parts, assistance vital to maintaining, repairing and operating this transmitter. Printed on high quality acid-free bond paper size 8 1/2" x 11", bound in a water resistant binder. This is a heavy manual, so I apologize for the higher shipping costs, but it's worth it."

The guy had good feedback, so I bought a copy to see what kind of "high quality" he was talking about. Note his description focuses mainly on the radio, and does not describe the quality of the text or images. Beware! Unfortunately, the quality of the printing and images was about average and similar to the .pdf files which were available from the BAMA mirror website/s for free. I would have done much better to make copies of the original manual at the AWA Annex. I did in fact make copies of the original manual at the Annex for the pages that were most difficult to read. 

Also downloaded manuals & schematics (.pdf format) from the BAMA mirror site. Some of the images (photos) were unreadable. Most of the text was fine.

November 6, 2007 (Tuesday):
Spent the day at the AWA Annex. Got an antenna relay and plug (see photo). Also made some photo copies of selected pages from the Johnson Viking Valiant manual.

110 Vac antenna switching relay (before restoration) and power plug

Antenna switching relay (110 Vac) and power plug made from an HC6 crystal case, and zip cord (courtesy: W2BSN). Note the relay SO-239 connector designations: "T" (transmitter), "R" (receiver), and "A" (antenna). The "HC6" power plug mates with a socket (J4) on the back of the radio, and the brown zip cord needs to be soldered to the tabs of the relay coil (one tab is visible in photo). The bracket with the holes is for mounting the relay to the rear of the radio cabinet. When the transmitter is keyed, the socket at the back or the radio supplies 110 Vac for the purpose of energizing the relay coil and pulling the contacts in so that the transmitter is connected directly to the antenna feed line. When the operator is finished transmitting, the relay coil is de-energized (the 110 Vac drops out) and it goes back to its normal state, which is to connect the receiver directly to the antenna feed line. I tested the relay on December 31, 2007 and it worked fine. It performed somewhat less than perfect in action however. I cleaned the SO-239 connectors with silver polish, cleaned the contacts with fine sand paper, lubricated the pivot point, and bent the center pole (the moving contact) of the relay as to make it work 100% of the time.

November 8, 2007 (Thursday):
Spoke with Bob Harrison (W2ICQ) on the phone. He has a lot of experience with these particular radios and is willing to help out if needed. He sent a "mode" knob with a white "dot" insert. Price: $5.00. Bob lives near Syracuse, NY.

November 11, 2007 (Sunday):
Carried the 83 pound Valiant down to the "operating theater" and changed the two 10A 3AG fuses (F2, F3) which were in the AC plug with the correct value, 8A 3AG fuses.

AC plug with correct 8A 3AG fuses installed

Top (left) and Bottom (right) of Johnson "Viking Valiant" chassis

Removed three long, 14" (actually: 13 13/16") 10-24 round-head bolts and star washers from the rear of the cabinet. There were supposed to be four bolts, but one was missing. Also removed nineteen short (", 10-24, round-head) bolts at the back of the cabinet. There were supposed to be twenty, but one was missing. Slid the chassis out the front of the cabinet. The 14" long round-head bolts were supposedly available through vendors listed in the back of Electric Radio magazine, but I struck out there. I soon located them on the McMaster-Carr website. The short round-head machine screws and star washers were available at Debbie Supply.

After removing the chassis, I did a quick visual inspection and noticed some melted shrink tubing (see photo) connected to the plate of one of the 6146 modulator tubes (V16). It revealed a burned resistor (22 Ω, watt, carbon, 10%). The resistor (R48) is part of a parasitic suppressor and can easily be fixed.

Also noted the band switch arm (D1) was binding on the internal cam (D2) (see photo) that switches the three VFO tank circuits (three separate frequency ranges) by way of the planetary drive assembly (D3) (not shown in photo). The first band switch position is for 160 and 80 meters. The band switch will activate the cam D2 (and the second VFO circuit) for 40, 20, 15, and 10 meters. A third cam position is used for 11 meters. The band switch (SW3) only had a few clicks before it hit the cam, but without rotating the cam. The photo shows the tines (fingers) of the band switch drive arm (D1) which are supposed to engage and rotate the cam (the square "E" shaped gray thing), but the cam was frozen. Lubricate the cam shaft from the bottom, or by removing the side cover of the VFO box.

November 16, 2007 (Friday):
Purchased cabinet hardware: Extra-long (14"), 10-24 thread, pan-head bolts. See Notes.

November 25, 2007 (Sunday):
Replaced resistor R48 (22 Ω, watt, carbon, 10%).

Tried to free up the band switch (SW3). The cam lobe would not rotate when the knob was moved to different positions. Removed the left side of the VFO enclosure and sprayed some contact cleaner-lubricant on the switch to no avail. Also dripped some penetrant (Liquid Wrench) on the camshaft from under the chassis. The entire switch assembly finally broke loose, but the wires inside the VFO enclosure were moving along with the switch and they might have broken. So I removed the cam lobe with a hex (Allen) key, and tightened the nut so the switch assembly would not rotate. Let sit overnight and try again tomorrow.

December 4, 2007 (Tuesday):
Took the day off from work and went to the AWA Annex. Several of the guys tried to free up the band selector switch to no avail. The switch did begin to move when two 250 watt soldering guns were placed against the shaft of the switch. But as soon as the shaft cooled it would freeze up again. I expect that it will require more heat (possibly a small butane torch) to free it up.

December 6, 2007 (Thursday) 19:00:
Went to Lynn's QTH (W2BSN) and freed up the band switch. Talked to Chuck (K1TLI) earlier in the day via email, and he suggested removing the small circular retaining ring at the base of the switch shaft. I had not noticed the retaining ring prior to his message. Believe it or not, removing that retaining ring was the key to solving the frozen band switch problem! Many thanks to both Chuck and Lynn on this one.

Removed the square cam (D2) first. Gently removed the small circular retaining ring that is around the base of the switch shaft, on the underside of the chassis. An awl or the edge of a small screwdriver will work. First, we applied some heat from a small butane torch, which has a small, controllable flame. Then, using a Q-tip, apply some penetrating oil on the shaft where the ring was removed. Use a small "vice grip" pliers to work the shaft back and forth, and up and down to free it up. If it moves up or down too much, the ball bearings can fall out of the switch on the top side. You can get them back in place, but it takes some patience. The circular retaining ring was blocking any lubricant from getting down into the shaft and that is why all previous attempts to lubricate it failed. The retaining ring needs to be removed first! When it is free simply take a pair of needle nose pliers and reset the ring by squeezing it. You can use this same procedure on any rotary switch.

Reset the cam block (D2) so that the band selector knob on the front panel lines up correctly with the switch. The positions for 160, 80 and 40 meters are at one VFO switch setting. Positions for 20, 15 and 10 meters are at the second VFO switch setting, and 11 meters is the third setting.

Skip to Repair History, Continued...

Table 2 (part I)
Replacement Parts for E.F. Johnson Viking Valiant
Compiled: 13-nov-2007 through xx-xxx-200x. Placed order: multiple days
Vendor 1 (for reference): RD (Radio Daze) - www.radiosupply.com
Vendor 2 (for reference): AES (Antique Electronic Supply) - www.tubesandmore.com
Vendor 3 (for reference): MC (McMaster-Carr) - www.mcmaster.com
Vendor 4 (for reference): M (Mouser) - www.mouser.com
Schematic part number Value (original) Original component and composition Value (replacement)
Composition of new part Vendor (Part number) Price ($) Quantity (actual) Purchased / Ordered Date Total ($)
    "mode" knob. plastic with white "dot" insert   "mode" knob. plastic with white "dot" insert Bob (W2ICQ) 5.00 1 1 08-nov-2007 5.00
    Extra long cabinet bolt. 13 13/16", 10-24 thread, round-head   14", 10-24 thread, pan-head MC (99117A610) 9.29 (package of 5) plus 4.50 shipping 4 5 16-nov-2007 13.79
R3 18k Ω, 2 watt, 10% resistor, carbon 20k Ω, 10 watt, 10% metal oxide RD (R-PW10-20K) These were not exactly correct, so I ordered the 18k wire wound resistors from Mouser 0.50 1 2 27-nov-2007 1.07
R3 18k Ω, 2 watt, 10% resistor, carbon 18k Ω, 5 watt, 5% wire wound M (71-CW5-18K) 1.03 1 2 30-nov-2007 $8.87 (2.06 plus $6.81 freight)
C89 0.5 µ, 400V capacitor, wax paper, axial leads 0.47 µ, 630V capacitor, metallized polyester film, axial leads RD (C-MF.47-630) 0.93 1 2 17-dec-2007 1.86
C91 80 µ, 450V capacitor, electrolytic, axial leads 100 F, 450V capacitor, electrolytic, axial leads RD (C-EA100-450) 3.99 1 2 17-dec-2007 7.98
C92 80 F, 450V capacitor, electrolytic, axial leads 100 F, 450V capacitor, electrolytic, axial leads RD (C-EA100-450) 3.99 1 2 17-dec-2007 7.98
C92A 15 F, 350V capacitor, electrolytic, axial leads 22 F, 450V capacitor, electrolytic, axial leads RD (C-EA22-450) 1.49 1 2 17-dec-2007 2.98
C92B 15 F, 350V capacitor, electrolytic, axial leads 22 F, 450V capacitor, electrolytic, axial leads RD (C-EA22-450) 1.49 1 2 17-dec-2007 2.98
C98A 15 F, 450V capacitor, electrolytic, axial leads 22 F, 450V capacitor, electrolytic, axial leads RD (C-EA22-450) 1.49 1 2 17-dec-2007 2.98
C98B 15 F, 450V capacitor, electrolytic, axial leads 22 F, 450V capacitor, electrolytic, axial leads RD (C-EA22-450) 1.49 1 0 (Ordered 6, above. Only needed 4.) 17-dec-2007 N/A
C99 10 F, 25V capacitor, electrolytic, axial leads 10 F, 160V capacitor, electrolytic, axial leads RD (C-E10-160) 0.59 1 2 17-dec-2007 1.18
NYS tax on capacitors: C89, C91, C92, C92A, C92B, C98A, C98B, C99 17-dec-2007 1.99
Table 2 (part II)
More Replacement Parts for E.F. Johnson Viking Valiant
Compiled: 31-dec-2007 through 02-jan-2008.
Vendor 1 (for reference): RD (Radio Daze) - www.radiosupply.com
Vendor 2 (for reference): AES (Antique Electronic Supply) - www.tubesandmore.com
Vendor 3 (for reference): MC (McMaster-Carr) - www.mcmaster.com
Vendor 4 (for reference): M (Mouser) - www.mouser.com
Schematic part number Value (original) Original component and composition Value (replacement)
Composition of new part Vendor (Part number) Price ($) Quantity (actual) Purchased / Ordered Date Total ($)
I1, I2 Type 51 pilot lamp, bayonet base. One for green "power on", two for VFO dial. Type 51 pilot lamp, bayonet base RD (DL-51) 0.34 3 (parts list shows two, but there are three) package of 10 02-jan-2008 3.40
I3 Type 6S6, 120V pilot lamp, screw base, 120 v. For red transmit light. Type 6S6 pilot lamp, screw base, 120 v Glenwood Sales 1.00 1 2 02-jan-2008 2.14

Table 3 (Part I)
Parts Needed for Separate AM Transmitter and Receiver
Compiled: 13-nov-2007 through 17-dec-2007. Placed order: 17-dec-2007.
Vendor 4 (for reference): UR (Universal Radio) - www.universal-radio.com
  • Microphone adapter cable (2-conductor, shielded) with: 4-pin, male microphone jack (plug) on one end for the Kenwood "TS-530S", and a  2-pin, male microphone jack (Amphenol 80-MC2M, 2-pin male) on the other end for the "Viking Valiant"
  • Multiple RG8X coaxial "jumper cables" to accommodate the antenna relay for the Viking Valiant transmitter and Hallicrafters receiver, and to allow the AM station to be located on other side of the shack (possibly*) from the SSB (Kenwood TS-530S) HF transceiver.
  • *May need to build shelves for the Viking (transmitter) and Hallicrafters (receiver) so that they can be located near the other equipment and the common ground point.
  • Switch (with SO-239 connectors) to toggle between the SSB (Kenwood) rig and the AM (Viking) rig.
  • Price comparison: It would cost $39.30 to buy (and "D.I.Y.") 32.5' of RG8X coaxial cable and ten (10) PL-259 connectors.
  • Price comparison: It would cost $39.90 to buy six (6) pre-fabricated RG8X coaxial jumper cables from vendor [(5) 18" cables, (1) 25' cable = 32.5'] with PL-259 connectors soldered on each end.
Part Description Vendor (Part number) Price ($) Quantity Date Total ($)
Microphone Jack 2-pin, male, chassis mount (for Johnson "Viking Valiant") UR (2793) This part was incorrect. The actual 2-pin plug is an (Amphenol 80-MC2M, 2-pin male) 2.99 1 17-dec-2007 2.99
Microphone Jack 4-pin, male (adapt to Kenwood "TS-530S" mic. cable) UR (2398) This part was incorrect. Wanted the shell, but this was the chassis mount 2.89 1 17-dec-2007 2.89
Microphone Cable 2-conductor, shielded ("Heil" brand: Two 18 gauge audio leads residing in a 100% silver braided shield) UR (2645) 1.00/foot 20' roll 17-dec-2007 19.95
Switch 2-position, 500 MHz, with SO-239 connectors (Alpha-Delta "2B") UR (4787) 56.95 1 17-dec-2007 56.95
Coaxial cable (RG8X) jumper cable, 18" with PL-259 connectors soldered at each end UR (2578) 4.99 5 17-dec-2007 24.95
Coaxial cable (RG8X) jumper cable, 25' with PL-259 connectors soldered at each end UR (0539) 14.95 1 17-dec-2007 14.95
Shipping & Handling 17-dec-2007 9.95
Total 17-dec-2007 132.63
Table 3 (Part II)
More Parts Needed for Separate AM Transmitter and Receiver
Compiled: 04-jan-2008. Placed order: 04-jan-2008.
Vendor 4 (for reference): UR (Universal Radio) - www.universal-radio.com
  • Additional (longer) RG8X coaxial "jumper cables" to accommodate the antenna relay for the Viking Valiant transmitter and Hallicrafters receiver, and to allow the AM station to be located on other side of the shack (possibly*) from the SSB (Kenwood TS-530S) HF transceiver.
Part Description Vendor (Part number) Price ($) Quantity Date Total ($)
Coaxial cable (RG8X) jumper cable, 36" (3') with PL-259 connectors soldered at each end UR (2580). (Astatic A8X3) 6.49 3 04-jan-2008 19.47
Shipping & Handling 04-jan-2008 4.95
Total 16-jan-2008 24.42
  • Type FT-243 crystal (3.837 MHz) for use on the AWA Sunday afternoon AM Net. This crystal served as a backup in case of VFO problems.

Part Description Vendor (Part number) Price ($) Quantity Date Total ($)
N/A Type FT-243 crystal (3.837 MHz) Brian Carling (AF4K/SK) 12.00 1 15-jan-2008 12.00
Shipping & Handling 15-jan-2008 5.00
Insurance and Priority Mail 15-jan-2008 (arrived 22-jan-2008) 4.00
Paypal Offset Fee 15-jan-2008 1.00
Total 15-jan-2008 22.00

Repair History, Continued...

December 7, 2007 (Friday):
Ordered a 5 oz. can of "Nevr-Dull" [sic] "Magic Wadding Polish" from www.amazon.com. This enabled me to clean the tarnished silver tank coils (L13A and L13B). Price was $2.82 plus $6.27 freight for a total of $9.09. Arrived on December 12. The tank coils looked much brighter afterwards, you'll agree.

December 16, 2007 (Sunday):
Used a product called, "Goddard's Silver Dip" (10 oz. jar) to clean up the numerous silver switch contacts. Used in conjunction with generic (Q-tip type) cotton swabs on each individual switch. The Goddard's Silver Dip was purchased at Wegmans grocery store.

Took inventory of the electrolytic capacitors I needed to replace. (See Table 2).

December 17, 2007 (Monday):
Placed order with Universal-Radio for pre-fabricated RG8X coax "jumper cables", microphone connectors, and microphone cable (See Table 3). Picked up replacement capacitors (See Table 2) from Radio Daze.

December 30, 2007 (Sunday):
Replaced electrolytic and paper capacitors: C89, C91, C92, C92A, C92B, C98A, C98B, C99. For detail, see Table 2.

December 31, 2007 (Monday):

Resistor R3 (a.k.a. the "Chernobyl" resistor) tends to overheat, so it was replaced as a precaution.

Replace resistor R3 (18k Ω, 2 watt, carbon) with a 18k, 5 watt, 5% wire-wound resistor. This was a precaution because R3 is known to overheat. Due to its location, it may be necessary to clip it out and drill holes through the chassis to relocate it on a terminal strip (a modification) on the other side of the chassis. This would keep it away from other things that can melt. The R3 resistor is located inside the VFO compartment. It goes to the voltage regulator tube (OA2 - V2) next to the VFO tube (6AU6 - V1) and is accessible by removing the plate on the left side of the VFO compartment. This is part of the screen voltage regulation for the VFO screen. Note that the theory about moving resistor R3 outside the VFO box to keep things from overheating may be a misnomer. The heat from the R3 resistor may also help to stabilize the VFO when everything is warmed up. The metal VFO box was provided for a reason, and it may have been to create an oven effect. However; I am not sure about it at this point.

Put radio back together, re-assemble VFO box, replace vacuum tubes in sockets. Attach dummy load (Cantenna) and solder leads to the antenna relay. Apply power from variable transformer. No smoke. Plug antenna relay into socket on back of radio and test. The antenna switching relay was good. Later experienced a problem with the antenna relay (a.k.a. "T/R switch") whereby the relay contacts would not release when the PTT switch was released. Need to investigate or get a new T/R switch.

Needed a Type 6S6 pilot lamp (120V, screw base). Lamp is used when transmitting - through the red lens to the right of the VFO. Needed three Type 51 pilot lamps (bayonet base). One Type 51 lamp is for the green power lamp, and the other two are for the VFO tuning dial.

January 2, 2008 (Wednesday):
Purchased two spare Type 6S6 bulbs (lamps) for "transmit mode" at Glenwood Sales. Picked up a package of ten Type 51 bulbs (lamps) for "power on" and VFO dial at Radio Daze.

January 4, 2008 (Friday):
Bought an Astatic D-104 microphone for $20. Schematic was included. Base plate cover missing. Otherwise in decent shape. Tested it, and it worked fine (got modulation).

January 5, 2008 (Saturday):
Soldered 2-pin connector onto D-104 microphone cable. The 2-pin connector is an Amphenol Type 80-MC2M.

Began following the tune-up procedure as described in the Viking Valiant Operating Manual. Tuned the pi-network into a 50 Ω dummy load (Heathkit "Cantenna"). All bands tuned up well except for 160 and 80 meters. There was no grid current on these bands. Brought radio back up to the shack and ran the coaxial cable and ground wire to it. Continued with the tuning process. The band switch internal cam (D2) may be out of alignment. I was also not able to "zero beat" any signals on the "presumed" bands. This could be due to the band switch alignment issue. Needed a frequency counter to verify.

January 8, 2008 (Tuesday):
Used my Kenwood TS-530S transceiver as a "digital frequency counter." Turned the Valiant up on its end, and switched it on. Set the band switch to 40 meters (was able to tune that band earlier) and set Valiant's VFO vernier dial to the low end of the band (near 7 MHz). Turned on the Kenwood, and listened to the low end of 40 meters. Was able to hear the zero beat signal on all bands except 80 and 160. Something was still wrong with those bands.

Compared my band switch cam block settings with photos from another Viking Valiant. Verified that my cam block is set up correctly. See photos of the cam block position on each band switch setting.

January 9, 2008 (Wednesday):
Removed the VFO box again and began looking for evidence of something which might have caused the VFO not to oscillate on the 80 m and 160 m bands. Used compressed air, vacuum cleaner, DeoxIT contact cleaner, some probing tools (needle-nose pliers, dentist type implements). Was able to separate a couple of wires that looked close to each other, applied the DeoxIT on the tube sockets of the VFO tubes, and the contacts of the band switch wafers. I wanted to identify something specific, but nothing appeared to be obviously wrong. Whatever I did, the problem was resolved. Was then able to see ample grid current on the 80 and 160 meter bands. It tuned up nicely into a 50 Ω dummy load on all bands.

January 10, 2008 (Thursday):
Made the first QSO with the rig. Talked to Ray (KC2OHL) on 3.837 MHz. He said it sounded good.

January 11, 2008 (Friday) 18:00 - 18:45:
Had an extended testing QSO with Dave (KA2J). He said the audio was real good, and that audio modifications are probably not needed for this particular Valiant. I varied the CLIPPING dial settings and he said that full clockwise sounded the best, but the ten o'clock position (3 on the dial) sounded as if there was more "power" to the audio. Left it in the full clockwise position.

Became aware of a vibration during transmit. Sounded like something loose inside a tube, but I was not sure. This was verified as normal "talkback" from the transformer, and does not indicate any trouble.

Noticed that the T/R switch was not always releasing after I let up on the PTT. Also, had to switch the receiver (Hallicrafters S-40) into stand-by mode in order to prevent massive amounts of audio feedback during transmit on the Valiant. This is standard practice with many operators of older AM equipment. It can be eliminated by using a T/R switch with another set of contacts that would need to be wired into the receiver's audio circuit such that when the operator is transmitting, the T/R switch would disable the receiver's audio.

January 12, 2008 (Saturday) 10:00 - 14:00:
Performed an operational set up, and calibration per the Operating Manual with Dave (KA2J). Dave brought his frequency counter, and vintage watt meter (TS-1771/U made by Electro Impulse Laboratories under contract by the Navy Bureau of Ships).

  1. Bias adjustment. Final amplifier. Adjust Clamper R13. Set R62 for -70 V amplifier grid voltage. Measure from either end of L7 and ground (chassis). L7 is under chassis (see layout photo in manual). Set chassis on end to perform measurement.
  2. Set static modulation current. Load transmitter to 8 mA grid drive, 330 mA plate current. Turn meter switch to MOD position. Adjust R61 to 60 mA (operating conditions are 50 - 70 mA).
  3. Clamper - R13 (pot near rear of chassis next to clamper tube V8 (6AQ5). Adjust by checking plate current when turning SW8 (MAN / PTT) switch to MAN position. Turn SW8 back to PTT position, and then adjust R13 ccw until 10 mA static plate current is achieved.
  4. Neutralization: Tune up on 20 meters to 250 mA. Note Final dial setting. Turn meter to grid position. De-tune final slightly in direction that causes grid current to increase. Completed when de-tuning causes little or no change or grid current falls off. There was not reason to adjust this, as it was set up fine.
  5. VFO calibration. Use adjustment taps on top of VFO box. Adjusted all bands: 160, 80, 40, 20, 15, 10, 11 meters.
  6. Load Valiant on 160, 80, 40, 20, 15, 10, 11 meters.

Later in the afternoon, I worked on the T/R switch. Removed the silver end-cap and cleaned the relay contacts with DeoxIT contact cleaner. Also lubricated the pivot point of the actuating bar with light oil (the oil was designed for model trains). the T/R switch performed with 100% reliability afterwards.

Made a patch cable for the T/R switch (antenna relay) to receiver. The Hallicrafters S-40 receiver has screw terminals for the antenna connections. Patch cable consisted of: PL-259 to coaxial cable (2 feet). Both center conductor and shield uses a spade lug. The center conductor lug goes to the separate antenna screw terminal on S-40. the shield lug goes to double-screw (jumpered) terminals on S-40.

January 13, 2008 (Sunday) 16:00 - 17:30
Checked into the Antique Wireless Association (AWA) Sunday afternoon AM Net on 3.837 MHz. Signal reports were all favorable. Bob (W2ICQ) in Syracuse (75 miles away) reported a "25 over S9" signal. Used the D-104 microphone and the Hallicrafters S-40 receiver. Antenna was a 113' (34 meter) #14 AWG solid copper enameled random wire up about 15' (5 meters). I was told that the radio does not need any audio modifications, and sounds good in stock condition.

N2AWA / AM station / January 14, 2008

1946 Hallicrafters S-40 Receiver (left), Astatic D-104 microphone (with amplifier bypassed), 1955-1962 Viking Valiant AM transmitter (right).

Distorted Audio Saga

December 28, 2008 (Sunday) 15:30 - 16:15
I checked into the Antique Wireless Association (AWA) Sunday afternoon AM "Pre Net" (as usual) on 3.837 MHz and received several reports of distorted audio on my signal peaks. I began checking the basics, and discovered some AC line voltage on the chassis ground stud! Depending on how the power plug (original two-conductor style) was positioned in the wall outlet, I measured either 31 v AC, or 61 v AC on the chassis. This explained those friendly little zaps I was getting when I touched the cabinet.

To (hopefully) fix the problem, I replaced the six "low"-voltage-coil bypass capacitors (C65, C66, C67, C69, C70, C71) where the AC line comes into the transmitter. They were all tied to ground (see schematic detail, directly above). If one (or more) of those ceramic capacitors was leaky, it could explain why there was some AC line voltage on the chassis.

January 1, 2009 (Thursday):
Photo (left): Original, unmolested configuration. The low voltage coils with the old ceramic disk bypass capacitors on terminal strips, screwed to the chassis. Photo (right): Unsoldered the coils to gain access to the (2) terminal strips.

New "orange drop" polypropylene capacitors (0.0047 F, 600 v)

Three of the old ceramic disk bypass capacitors (0.005 F, 600 v) and one of the terminal strips. There were two of these configurations hidden behind the coils (see photo, above).

Same old terminal strip with the new capacitors soldered into place. Did this make any difference? I measured 20 Vac on the chassis after replacing the capacitors, so that was better than what I measured before, still not perfect. Not sure where the 20 volts could still be coming from, unless one of the new caps was leaking, which was unlikely.

An Excuse To Buy A New Antenna

Unfortunately, none of this horse hockey explains the "distorted audio" reports I was getting. So to that end, I ordered a full sized (no coils) Hy-Power 80 meter dipole antenna. The existing end-fed, random long wire antenna was difficult to tune on 3.837 MHz and I could not fully load the wire with the Valiant without getting some arcing inside the MFJ-949E antenna tuner. That arcing is what caused the distortion. Description of the new 80 meter dipole: Full-sized (no coils), full power dipole. Features #12 AWG UV insulated wire, uses stainless steel electrical hardware, an SO-239 center insulator, and two end insulators. The antenna was completely assembled and ready to install. Just added coaxial cable and nylon rope. Antenna length: 42 meters (138 feet).

January 5, 2009 (Monday):
The Hy-Power 80 meter dipole antenna arrived.

Table 4 (part I)
80 meter Dipole Antenna and Replacement Parts for E.F. Johnson Viking Valiant
Compiled: 30-dec-2008.
Vendor 1 (for reference): RD (Radio Daze) - www.radiosupply.com
Vendor 2 (for reference): UR (Universal Radio) - www.universal-radio.com

Schematic part number Value (original) Original component and composition Value (replacement)
Composition of new part Vendor (Part number) Price ($) Quantity (actual) Purchased / Ordered Date Total ($)
N/A N/A N/A antenna rope. double braided polyester, 1/8", 100', 420 lbs. break. UR (2624) $11.95 + $4.95 shipping N/A 1 (100 foot) roll 03-dec-2008 $16.90
N/A N/A N/A 75/80 meter dipole antenna. Length: 42 meters (138 feet). #12 AWG, UV insulated wire, with stainless steel electrical hardware, SO-239 type center insulator, and two end insulators. UR (1292) Hy Power (FSDP 80) $48.95 + $4.95 shipping N/A 1 29-dec-2008 $53.90
C65, C66, C67, C69, C70, C71 0.005 F, 600 v ceramic capacitor 0.0047 F, 600 v "orange drop" (type 715P) polypropylene film capacitor RD (C-OD15.0047-600) $0.54 6 8 30-dec-2008 $4.32+$0.31 tax=$4.63

80 meter Dipole Antenna

Lynn (W2BSN) visits with his home-brew air cannon to help install the 80 meter dipole antenna.

February 7, 2009 (Saturday)
Erect 80 meter dipole antenna. "Hy Power" model FSDP 80 (#12 AWG UV insulated wire). Total antenna length: 138 feet. Handles 1,500 watts.

Lynn brought his home-brew, compressed-air cannon to get the ropes up into the trees. He used light-weight, pink string (for maximum visibility) with a weighted projectile (wooden dowel encased in a metal sleeve) at the end. This served as the feed line for the antenna rope, which is heavier. We spent about four hours on Saturday. I went back out on Sunday (February 8, 2009) to take down the old long wire antenna and re-purpose the antenna rope (from the long wire) to the center insulator and south end of the 80 meter dipole insulator. Also ran the coax feed-line up under the eves, behind the gutter. I was out there for another three hours Sunday. It took a total of 11 man-hours to complete the work. Signal reports on the Sunday afternoon AWA AM Net (3.837 MHz / 1600 local time) were favorable. The signal strength was reported to be much stronger than with the random, end-fed, long wire. The new 80 meter dipole antenna also helped the 1946 Hallicrafters S-40 receiver.

April 14, 2012 (Saturday)
After the Newark Hamfest, Kevin (WB2QMY) helped fix my "drooping" 80 meter dipole antenna by climbing the 40 foot pine tree* and running new rope through a vintage ceramic insulator. A cordless drill made a pilot hole for the insulator. The main cause of the droop was that the counter-weight (a plastic milk jug filled with sand) disintegrated and broke free, creating about five feet of slack in the system. To make matters worse, the original polyester rope was stuck in the top of the tree, preventing that end of the antenna from being lowered, as originally designed. *Kevin was more than half way up the tree in this photo, but invisible a truly majestic tree.

November 1, 2013 (Friday)
The antenna saga continued...with high winds snapping the rope. On Saturday November 2, I climbed the tree in the rain, and dropped new rope on both sides, and hoisted the system back into place. Was unable to locate the ceramic insulator that was installed on April 14, 2012. Also noticed the clear insulation was peeling off the #12 AWG wire.

Low Modulation Problem

AMfone Forum: My "low modulation" problem

August 5, 2013
Smelled a burning odor while transmitting on the AWA AM Net (7:00 p.m. / 3.840 MHz), so everything was shut down quickly. At that point, it was not clear if the receiver (1946 Hallicrafters S-40) or the transmitter was the culprit. After the dust settled, I tuned-up the Valiant and ran some tests, and everything seemed fine (there was modulation, the finals would load, and the plate current was dipped).

Bob (W2ICQ) said one of the loading capacitors in the pi-network may have failed because they are known weak points. He suggested replacing them with "military" mica capacitors (presumably to withstand higher temperatures, etc.). The manual says the fixed caps in the pi-network are mica, but I presume not military grade. The pi-network loading circuit is shown at the top right of the schematic. As the "Aux Coupling" and "Fine Tune" knobs are turned clockwise, the capacitance is reduced, thus loading (coupling) the transmitter to the load for full rated power input. The modulation issue did not seem to be tied to the loading caps, but the weakness of these original caps was good knowledge for future reference.

I made two AM contacts who said my audio was low. I was getting raspy sounds from the modulation transformer plates, and noticed the modulation meter swinging a great deal. After backing WAY OFF on the AUDIO pot, the raspy sound ceased and the modulation meter was more normal, but the other stations could not hear me well. Then everything was shut down again.

The transmitter was able to be loaded and I could dip the plate current, so the RF side of the radio seemed to be working. The modulation side needed help. Perhaps a plate resistor on one or both of the 6146 modulation tubes was toasted (this happened before - see "November 11, 2007" on this page). Not a lot in the way of capacitors in the area, so not sure how a resistor could get fried (by a shorted cap), but it provided a place to start looking. The modulation "chain" is shown along the bottom of the schematic.

August 6, 2013
Got the transmitter down into the workshop for further analysis.

Discovered charred plate resistor wires under the chassis. The inductor (choke) was removed to gain access. In principle, a choke (a.k.a. inductor) blocks high frequency AC and passes DC current.

Detail of charred modulator plate resistor wire (on right).
L45 (choke / inductor) was removed to view damaged area.

Comparison Photo: Modulator plate wires in 2007. They were both still white!

The wires shown in the photo are the modulator tube wires that lead to the modulator transformer T3. Removed the 22 Ω plate resistors (affixed with metal cap on modulator tubes), and measured the exact same resistance from each plate resistor to ground on each side of the modulation transformer primary, so the transformer looked good.

August 7, 2013

Bob (W2ICQ) saw the photos and said it simply looked like the phenolic terminal strip broke down. There are six terminals on the strip, and replacements are available at Antique Electronic Supply (www.tubesandmore.com).

Terminal Strip / 6 lug / 0 common / horizontal

Antique Electronic Supply p/n: P-0600H
Price $4.00 / August 2013

Original (NOS) phenolic terminal strip / Courtesy: Bob (W2ICQ)
Fortunately, Bob had one in his stash and popped it into the mail.

August 15, 2013

  1. Drilled out the rivets of the original terminal strip.
  2. Secured the NOS terminal strip with nuts, bolts, and washers.
  3. Snipped the metal terminal posts off the old strip (with the wires still soldered to them).
  4. "Tack-soldered" the wires to the new terminal strip posts (eliminates dealing with old, possibly brittle wires).
  5. Tuned and loaded the transmitter into a dummy load (Cantenna).
  6. Checked modulation with D-104 microphone (modulation looked good on the meter).
  7. Put it back into the cabinet.

Thanks to Tim (WB2PAY) for helping on this repair. The technique of snipping the terminal posts (with the wires attached – and tack-soldering them to the new terminal strip) came from his television repair days. I was skeptical at first, but it turned out to be a tidy, effective solution. One of the terminal strip rivets needed more work being drilled out, so I used a Dremel grinding tool, and a prick punch to tap it out. Vacuumed the metal and debris multiple times before loading it into the Cantenna.

August 18, 2013 (Sunday)
Checked into the Antique Wireless Association (AWA) Sunday AM Net at 7:00 p.m. on 3.840 MHz (summer time and frequency). Signal reports were all favorable.

Valiant Knob Pointer Replacements (⅛" diameter x ¼" length)

Still To Do


1 Charles "Chuck" Brelsford (K2WW) was an early Antique Wireless Association (AWA) member along with Bruce Kelley (W2ICE), Lincoln "Linc" Cundall (W2LC), Ken Gardner (W2BGN) and Robert Morris (W2LV)


Many thanks to Lynn (W2BSN) for the power plug for antenna relay (HC6 crystal case), antenna relay, two-pin connector (Amphenol 80-MC2M) for microphone patch cable. Bob (W2ICQ) for the mode knob with white "dot" (pointer) insert, email advice and support. Chuck (K1TLI) for the advice on the band switch retaining ring. Dave (KA2J) for photos of his Viking Valiant band switch settings and help with the operational calibration. Bob (W2ICQ) for the NOS terminal strip on the low modulation problem. Tim (WB2PAY) for technique and assistance with tack-soldering old wires to new terminal strip.

c o n t a c t / r a d i o w o r l d
E.F. Johnson "Viking Valiant" AM Transmitter
Established: November 4, 2007
Last Update: October 29, 2020
Links Verified October 2, 2020
Black Sparrow Photography / Jeffrey P. Miller (N2AWA)