Restoring EF Johnson Viking Valiant

[NP4ZB]

 Hi to all,
I just received a EF Johnson Viking Valiant to
restore for a friend of  mine. The power cable is missing
I need to know do I need to install fuses on the power line.
I bought NOS 3B28 tubes and I also bought new capacitors.
I check and didn't see anything burnt or missing. I don't much about his
Transmitter.

Thanks for looking.

73's

[WQ9E]

Since the power cable is missing, I would replace it with a modern 3 wire cord.  A 6 amp fuse should be installed in the hot lead (the black lead) which is the one which should lead to the power switch.  

If you are not planning to use a SSB adapter with the Valiant you could remove the SO-239 connector that provides this input and use that hole for a fuse avoiding the need to drill an additional hole.  

You should also read the thread about Valiant meter shunts.

[NP4ZB]

 OK, that is great.
Thanks for the information.

[KD0HUX]

 Next on the list should be audio mods

[Ed/KB1HYS]

There are some great pages here about the valiant.  I own one and once you replace age worn components, and address a few known bugs, it's a good transmitter to tinker with.

I'd recommend -
1- Install a 3-wire modern grounded plug. Fuzes on rear apron, only fuze the line (hot) side (you also may want to change the line bypass caps - I think they should go from line to neut to ground, search the forum I know there is a thread).
2- Replace the electrolytics - bigger is better in this case.
3- check the shunts for the meter circuit, they are nicrome*(?) wire and were not soldered, but were crimped on. The meter may not read accurately, and that's your primary tuning/troubleshooting tool.
4-Check the rectifiery filament lines while you have it open, some units had poor filament wiring causing shorts.
5- The "special" (C-35??) loading capacitor is prone to failure, it's just a stack of plates and mica on a stand off. replace it with discrete fixed values of transmitting mica's or good doorknobs.
6- There is an 18K ohm 2 watt resistor in the VFO known as the "chernobyl" resistor, common to several Johnson rigs that us this vfo.  change it with any high wattage resistor (20K @ 10 watts FB).  you also may want to remote it to outside the VFO housing - your call on that one, it's tough to get in there.

That's it for safety/reliability.  After you do that, you can do what ever you want to the audio chain.

Oh yea, Buy LOTS of 6146's, that beast uses FIVE of them. Two modulators, three in the finals.!

[W2PFY]

Buy LOTS of 6146's

If you do go on a buying campaign for 6146 tubes, be sure to stay with all 6146 or 6146A. 6146B's can be a problem with neutralization etc.

If your interested in a lengthy but thorough dissertation on the 6146 family of tubes, I can post it.

[NP4ZB]

OK how about 6146w tubes?

[W2PFY]

Here is the link to the page. since there is a copyright, I cannot cut and paste but he'll explain all.


http://k9sth.com/uploads/The_6146_Family_of_Tubes_1.pdf

Let me know what you think of his finding? I have had other people caution me against mixing 6146 tubes and just ran across this last week.

It looks like the 6146W could be a different tube depending on when it was manufactured.

[WQ9E]

The W suffix tubes work fine in the Valiant but I wouldn't advise mixing within group.  So if you need to replace one final tube I would suggest going to W (B, etc.) for all three.  The 6146 tubes are not being stressed in the final so good ones will last a long time.  I have also used W suffix tubes in a Viking 2, Ranger, and numerous Heathkit SB and HW series radios.  The only case where I am personally aware of an issue is with some of the Collins gear where the neutralization circuit must be modified for W series tubes to work.  I have enough original 6146 tubes to keep my S line and KWM-2 supplied.

Some of the lore involving W tubes probably is due to at least one bad production run where the tubes were gassy and prone to flashover.  Fair sold (and replaced) a number of defective tubes from this surplus lot.  But it had nothing to do with the internal geometry or capacitance of the W variant and was purely a result of the production process.  I also received some of these from Fair in the mid 90's and they quickly replaced mine; I have no idea what the total number of bad tubes was or if it was all from the same production run.

NOTE!!!  For the audio clipper, please be aware that minimum clipping occurs in the full CLOCKWISE position of the clipper control.  If you set it to the "intuitive minimum", full CCW, it is actually set for maximum clipping and it will sound horrible.  At full clockwise the 6AL5 does not clip.

The Apache has a similar "gotcha" setup where one audio control (modulation level) is internal (accessed through the key jack) and if the hidden internal control is not set properly you will achieve the ultimate "scratchy Apache" sound by trying to get enough audio using the readily accessible control which increases clipping as you try to increase modulation level.  Setting the internal control properly first is critical with the Apache.  Apparently Heathkit and Johnson engineers were in a contest to see who could better mislead less careful readers into creating terrible audio  

[Jim, W5JO]

Let me know what you think of his finding? I have had other people caution me against mixing 6146 tubes and just ran across this last week.

The problems associated with the B and W tubes were primarily found in VHF land mobile equipment.  Collins had some neutralization problems with them in the 32S series but a small cap change fixed that.  That problem was up on 10 meters or so.  For the most part you should not have trouble with any of the 6146 family of tubes in Johnson equipment.  However I don't suggest putting an A with two B models in the final or mixing them unless you have a transcondutance tester and check them for a match.  

At audio there aren't any issues with the B version at all so if you are worried about that put plain and A versions in the final and the B or W version in the modulator.  Or find some 6293s and put them in.  They are a pluse duty rated 6146.  I think Glen metions them in his write up somewhere.

[Ed/KB1HYS]

The modulators won't care, though I (and a few others) have had neutralization troubles with the valiant when mixing 6146 types.  I think it even varies from rig to rig, so who knows. 

You could shoe horn in a 4X150, but you'd need a blower for cooling...  Evil Grin.

[NP4ZB]

 Hi again to all. Here is the latest,
I did the mods and installed new 3B28 TUBES.
Changed all caps. Did a test to today. All tubes turn
on accept the OC3 TUBES don't turn on. My question
is this normal? Any idea someone might have. please help.

Thanks.

[W2PFY]

While your waiting for a good answer, check the voltage at the pin on the 0C3 to see if  voltage is there. They may only come on perhaps when used with the VFO or for SSB?  Just a thought.

[WQ9E]

In CW mode, the 0C3/VR-105 tubes are not used.  In AM mode they regulate the modulator screen voltage and in SSB they are used to regulate the final screen voltage.  You should see them glowing in either AM or SSB mode but not in CW.

Make sure to check/set bias voltage for the modulator tubes as per the manual (and also for the final in SSB if you are using it with an adapter/low power exciter).  If you have a later Valiant (or an early one modified for use with the 6N2 transmitter) the adjustment is via 2 pots on the chassis side instead of taps on a resistor.  If you have the early model, modulator bias MUST be set with rated grid drive to the final.  The later bias scheme is independent of drive.

[NP4ZB]

  I have good news guys. The
EF JOHNSON VIKNIG VALIANT is
up running and working great. So far no issuses.
I left it on for about two hours, Before doing
any test. Power out put running at 150 watts.
The OC3 TUBES turn in  AM mode. Thanks
for the help.

73's de NP4ZB

[w3jn]

Outstanding!  There's nothing like the satisfaction of going thru all that and rewarded at the end with a FB working rig, instead of smoke 

[W2PFY]

GREAT that you got it running!! I have seen in one case, and others have mentioned problems, when running full strap on ten meter band where contacts in the band switch, melt or arc over.

Maybe someone can inform us how real a problem this could be?? Possibly what to do or not to do to keep it from happening.

[WQ9E]

I have used my Valiants on 10 numerous times (both CW and AM) at rated power and I have not run into any switch problems.  I DO NOT recommend switching the aux coupling control while the final is producing power as this does create a real probability of switch damage.  And just because the Valiant output network can work into a wide impedance range doesn't necessarily mean that is a great idea.  On 10 your biggest issue is probably going to be riding the VFO until it is very well warmed up because it is multiplied times 4 so any drift is also multiplied by 4.  Unless you are using a crystal it is going to have that "classic vintage sound" on CW and I don't believe any amount of adjustment of the keyer circuit is going to make that completely go away (although improper adjustment will make it sound really bad instead of just slightly bad).

If you are not sure the Valiant is properly neutralized, first check and adjust neutralization on 20 meters and then recheck on 10 meters after it is close and make whatever additional small adjustment is necessary.  This will lessen the chance of having an improperly neutralized final taking off on 10 meters creating damage.

[Ed/KB1HYS]

The valiant manual calls for neutralization adjustment on 20 meters, instead of the highest band (10).  I always thought this was a little odd...

[NP4ZB]

I notice that on the right of the chassis are two res/pots
marked R61 and R62. This valiant was built from a kit, but
it was built well. I made a contact with a friend on 10m/29.100MHz
The radio worked great, but one small detail,
the meter set on plate during transmitting it was pin all
to the right. It was working great earlier during testing.
The plate was reading 330ma now it's way over to right.
Does anyone has any idea what this could be?

73's

[WQ9E]

As soon as you notice excessive plate current it needs to be corrected immediately to prevent component failure.  It could either be a problem in the Valiant or your antenna tuner/antenna.  AM does put more stress on components than most other modes so marginal components in tuners or antennas will fail.

First, re-check your Valiant on a dummy load.  Tune it for rated power and let it run for a couple of minutes to check for increasing plate current.  If it does rise you have narrowed the problem down to the Valiant.  This could be a final tube going bad or a bad fixed cap in the output network.  Try this test and post the symptoms.  Also check to see what your grid current reading is during plate current rise.

[NP4ZB]

 Thanks for the info. I checked the plate curr. went down back normal.
The grid curr. is at 8ma. I check the final tubes yes there is
one is going bad, looks like I have to buy new ones. Thanks all for the help.

73's