Viking 500

[WA5VGO]

Old age is causing my memory to fade. I haven't used my Viking 500 for several months. I fired it up today and noticed that it shows a small amount of modulator current (15mA) and clamper current (12mA) in standby. This only in the AM mode. They both drop to zero with the mode switch in CW. I don't remember this before. The transmitter works fine. This doesn't seem right. Is it normal?

Darrell

[WD8KDG]

Start with the manual; Table 1 page 46. Haven't peeked at mine in a while, but at one time very close if not on the nose according to this table.

Craig,

[WA5VGO]

Start with the manual; Table 1 page 46. Haven't peeked at mine in a while, but at one time very close if not on the nose according to this table.

Craig,

The table doesn't show meter readings for standby conditions.

Darrell

[WD8KDG]

Start with the manual; Table 1 page 46. Haven't peeked at mine in a while, but at one time very close if not on the nose according to this table.

Craig,

The table doesn't show meter readings for standby conditions.

Darrell

I give up what is your standby condition?

Craig,

[N2DTS]

Nice transmitter!
Rare on the air these days.
Seems the bands are lousy with Globe Kings...

[Pete, WA2CWA]

Start with the manual; Table 1 page 46. Haven't peeked at mine in a while, but at one time very close if not on the nose according to this table.

Craig,

The table doesn't show meter readings for standby conditions.

Darrell

I give up what is your standby condition?

Craig,

His initial post. He's getting modulator and clamp current readings in standby.

[WD8KDG]

Nice transmitter!
Rare on the air these days.
Seems the bands are lousy with Globe Kings...

I like the looks of those lousy GK's.............

Craig,

[WD8KDG]

Start with the manual; Table 1 page 46. Haven't peeked at mine in a while, but at one time very close if not on the nose according to this table.

Craig,

The table doesn't show meter readings for standby conditions.

Darrell

I give up what is your standby condition?

Craig,

His initial post. He's getting modulator and clamp current readings in standby.

Verify.............verify.....verify.

Table 1 (ithinkshowsAMwithnomodulation) but can't remember looking for meter values with the TX on and not squeezing the chicken choker of the D104. But will give it a go this evening for Darrell.

Craig,

[flintstone mop]

Take it slow and sit down with the transmitter and think a little bit. Do not get anxious and start twisting knobs and hitting the transmit switch. Sit with the TX a little while and let your memory work for you how you would operate the rig when you wanted to call CQ.
It just may a tube that has some gas and needs replacement. ALWAYS be careful if you start getting into the HV circuits.
Take your time and let your memory be your guide.
These clamper current and mod current in standby might only be a meter switch problem that needs to be worked a few times with the rig turned off. Also try to rock the mode switch a little while the rig is off. If you are safe with HV unplug the unit and try to squirt DEOxit on these two switches. MODE and METER with the unit unplugged from the wall. It will require you to get access to these switches to spray the DE-Oxit on the actual contacts.
The next problem could be in the low voltage supply and a bad filter. Strange that your getting reading in STNDBY

Fred

[w1vtp]

Read the manual - a lot.  Look at the schematic. Pretend you just got it.

GL, Al

[WD8KDG]

Darrell,

The results are in! Took the time to warm up the shack and the infamous "Junkston 500" of Springtucky, Orygun.

Selected crapstall #1 (7.294MHz) loaded up the TX to, near, or about 300 mils of RF amp cathode current, frequency by the counter 7.2935MHz. This was in the CW mode.

Then unkeyed and switched to Angel Music. With the TX on and the Bird 43 swinging at 350 watts of RF and NO mudulation I had the following readings:

Clamper = 4 mils
Mod Cath = 25 mils

Now to your Question, Standby, not squeezing the chicken choker of the D104.

Clamper = 14 mils
Mod Cath = 0 mils

Also I claim a mistake. Out in the shack with my printed manual from BAMA, large print, Table 2 is what we should be looking at.

Craig,

[WD8KDG]

Food for thought:

The persons/engineer(s) that designed the "500" and put together the manual knew what they were doing, more ways than one. Fact that "500's" are still on the air today is plenty of proof.

With only the operation manual, my "500" was resurrected from the grave. Following the step by step, paragraph by paragraph, and the skizmatic it has been on the air since 2005. (with an occasional escape of magic smoke) I'll give credit to its design and a well written manual.

For what ever reason, E.F.Johnson Table 2 page 46 says to look at these values with the TX on! Standby must not of meant much to those engineers. ON counts more in this case.

Gud luck, have fun...........since it is the season Merry Christmas & a Happy New Year

Craig

[WA5VGO]

Thanks Craig! Very helpful info. It sounds like the clamper is normal and maybe the modulator is a little strange. I may just run it and see what happens. Everything seems fine into the dummy load.

As far as the Viking 500 is concerned, I completely agree with you. It was one of Johnson's finer moments. A solid transmitter and I really like the concept of a separate ps/modulator chassis.

Darrell,

The results are in! Took the time to warm up the shack and the infamous "Junkston 500" of Springtucky, Orygun.

Selected crapstall #1 (7.294MHz) loaded up the TX to, near, or about 300 mils of RF amp cathode current, frequency by the counter 7.2935MHz. This was in the CW mode.

Then unkeyed and switched to Angel Music. With the TX on and the Bird 43 swinging at 350 watts of RF and NO mudulation I had the following readings:

Clamper = 4 mils
Mod Cath = 25 mils

Now to your Question, Standby, not squeezing the chicken choker of the D104.

Clamper = 14 mils
Mod Cath = 0 mils

Also I claim a mistake. Out in the shack with my printed manual from BAMA, large print, Table 2 is what we should be looking at.

Craig,

[WD8KDG]

Darrell,

Give er a once over per Table 2 with the TX ON! If there are modifications to the audio section or brand X mod iron; your mileage may vary.

Craig,

[flintstone mop]

I was wondering how Darrel is doing with his 500?

[WA5VGO]

I was wondering how Darrel is doing with his 500?

Fred,

Thanks for asking.

It's working correctly now, but I'm still not sure what was going on. I went through the usual process of elimination and determine the current went away when the low voltage rectifier was removed. The most obvious cause was leakage between the primary and secondary of the audio driver transformer. I pulled the 6B4G driver tube out and, sure enough the current went to zero. So far, no surprises. It got weird when I plugged the tube back into the socket. The current stayed at zero. No matter what I try, I can't replicate the problem. I'm not sure what was going on, but I'm going to give it a shake down tomorrow, and if the problem doesn't return, I'm putting it back into the cabinet. 

Thanks again to Craig for his assistance.

73,
Darrell

[w4bfs]

I believe that there may have been some oxidation/corrosion on the 6B4 pins

[N2DTS]

If you put it back in the cabinet, the problem is sure to come back.
If you put all the screws back in who knows what would happen...
As long as its out of the cabinet, it will work great.

[flintstone mop]

Good troubleshooting. It may have been poor tube pin contacts to the circuitry
You have success

[w1vtp]

I believe that there may have been some oxidation/corrosion on the 6B4 pins

Yup

[K5WSY]

The 500 manual states that there could be an arc on the ps gap when unkeying. I made the first contacts on my 500 since the early 70's. There were arcs at the end of each transmission. Then one of the HV fuses blew. Now it arcs from the Millen HV connector I installed on the RF unit. I am about to run out of fuses. I wonder if any other 500 owners have had this problem? Thanks, Don K5WSY

[W2NBC]

Don,


There was a delay built in to RY-302 (relay) that degrades in actual time delay. Rodger, WQ9E posted this mod to address the arcing issues..


"Here is the "step by step" for taking care of the lost delay:

You will need a terminal strip (with at least two non-grounded terminals), a 1 KV rated diode, a 10uf @ 250V or greater capacitor, and a small length of hookup wire.

First, disconnect the white wire connected to the coil terminal of delay relay RY-302.  Install a terminal strip and mount the diode on the terminal strip.  Solder the white wire that was removed from RY-302 to the anode end of the diode.  Solder a short wire to the cathode end of the diode that is sufficiently long to reach the now empty coil terminal of RY-302.  Solder the 10 uf capacitor across the coil of RY-302, the capacitor positive lead connects to the coil terminal that is now connected to the cathode end of the added diode.

This provides a slight release delay for RY-302 when PTT is released while the plate transformer relay RY-303  will still release immediately.  10uf provides a very short delay but it was sufficient to take care of the problem with my 500.  A larger value will provide a longer delay but it shouldn't be necessary.  My transmitter started this intermittent flash over on release a few months after I bought it and I installed this modification in September of 2007 and the 500 has continued to work perfectly"

This post reference: http://amfone.net/Amforum/index.php/topic,33131.5

It seems to be a common problem with 500's

[K5WSY]

Thanks for the information. Rodger has been invaluable in giving me assistance. I had to replace that relay and installed the delay. I had some trouble blowing the bias fuse so I disconnected the delay.  After replacing the bias tube socket that solved that fuse problem. I have not hooked the delay back since the transmitter is hooked to the antenna without a relay. Thinking back, arcing was a problem when I got the transmitter in the early 1960's. When the original HV transformer shorted, I replaced it with a Gates transformer rated at 3000 volts. I wired it for 1500 and while it has been a long time ago I don't remember it arcing then. I need to recheck the voltage on the replacement I am now using. It is susposed to be a direct replacement, but it could be a little higher. I think it was around 2300. Thanks again for your help. 73, Don K5WSY