The AM Forum

Is there any one here in Ohio that does good work and reliable for doing Repair, I just purchased a Johnson Viking Pacemaker that i would like to have it gone over.. If you know of someone please let me know..Or i may just take on this challenge myself with replacing the Caps and tubes but i would really like to have someone go over it and realign it...Please Email me with any Advice..Thanks Chris N8YHY@SBCGLOBAL.NET

Chris,

Sorry I can't refer you to anyone in OH, but I did not want your request to go unanswered.

There is the Lake Erie Boatanchor group,  http://www.lakeerieba.com/

Allow me to suggest you do the job yourself.
I know that you can count on 100% help from the folks here on the BB and changing tubes and caps is really not that hard.

That's the nice thing about boatanchors, you can acutally see what you are working on and they have plenty of room for service.

Why don't you start out by telling us a bit more about the unit:

Is it working at all?

What would you like to see it do that it does not do now; better audio, etc.?

Any mods already done?

Do you have the schematic and manual?


73 Bruce W1UJR

Hi Chris,
 
That is a very nice looking rig, where did it come from?
 
Let's start with your problem, I am assuming you are using it on AM or SSB, they are the simplest modes to test and set up the rig.
 
First, do you have grid drive?
If not, then the clamper tube is pulling down to protect the output tubes.
The older Johnson gear has a big problem with the VFOs, specially a power resistor for the screen grid that is prone to fail.

Try using a crystal in place of the VFO, if you develop grid drive with the crystal you know you have an issue with the VFO stage.
You can find out more about this problem by Googling "Johnson VFO Resistor",
 
If you have grid drive, the next thing I would check for is correct bias to the final tubes, assuming it uses 6146s?
 
The nice thing about the older schematics is that they have voltage references for the various stages.
 
What I typically start with is a voltage check of the rig, you'll find that most of the faults can be discovered that way.
Also check the tubes, but don't put too much faith in a tube tester.
If I feel I might have a bad tube, I always substitute just to confirm.
 
A common failure on many of the Johnson units I have is the bypass capacitors on the rear octal socket.
And I assume that the Pacemaker needs the jumpers across the rear octal socket like the Ranger and Valiant?
 
The key to troubleshooting, and I tell my employees this each day, is to take the "system approach".
Understand that any device is just a collection of individual circuits which are now acting together.
If you follow the block diagram and test each system in a logical manner, you can not help but find the fault.
 
As far as electrolytic caps, try Antique Electronics Supply in AZ, Mouser, Digikey, etc.
I generally try to replace with a cosmetic similar item, given the find condition of your transmitter I assume you would do the same.
 
Give me some answers to the above questions and we'll work on getting your rig back on the air.
 
I am also going to post this reply in the AM BB for the benefit of other readers.
 
 
73 Bruce W1UJR

Hi Chris, That is probably the worst transmitter Johnson ever made. If you are looking for a good vintage AM transmitter I wouldn't invest a lot of time and money in the Pacemaker. You would be much better off with a Viking one, two, Valliant , DX100, etc.
73, George/W2AMR

Goerge i have a Johnson Valiant that works nicely, I did'nt want the Pacemaker for AM operation, I wanted it because it was clean and it was Johnson's SSB rig that they produced, But any way thanks for your thoughts..73 Chris

Bruce. Had a look on the Lake Erie Boatanchor Groups website. Found this little gem  http://www.lakeerieba.com/files/Hallicrafter%20Shortwave%20Adventure%20II.wav  I love stuff like that TNX.