[AMRadio] Johnson viking 2..


Jim Wilhite w5jo at brightok.net
Wed Jul 28 16:03:00 EDT 2004


----- Original Message ----- 
From: "Geoff/W5OMR" <w5omr at w5omr.shacknet.nu>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>
Sent: Wednesday, July 28, 2004 10:09 AM
Subject: Re: [AMRadio] Johnson viking 2..


>
>
>
> > What is the procedure for applying AC power to Johnson Viking 2
Transmitter
> > that has been in storage for many years?..Tnx es 73's Ron
>
> The best way, of course, would be to replace the capacitors.  But...
>
> Grab a VariAC, connect a Current meter in series, bring the voltage up to
around
> 25VAC, and if there's no current being drawn through the meter, then let
it sit
> for
> 24 hours. (when I say 'current', I don't mean that it's sitting at 25v,
drawing
> 4amps...
> obviously something is wrong there - it should remain under 1amp, even up
to
> full AC)
>
> if all is well, crank up the voltage to 50v and let it sit for another 24
> hours...
>
> this slow voltage increase will help 're-form' the capacitors, at the same
time.
>
> another 25v would put it at 75 - keep watching the current meter, and then
up to
> 100.  All should be fine.
>
> You could probably alter the times... but I'd not use less than 12 hours,
for
> each step.
>
> 73 = Best Regards,
> -Geoff/W5OMR
>
>

I suggest you check the capacitors if you have a checker.  Every boatanchor
I have put into service with original caps, has had either a failure or
almost so within a year or so.

I have found they have lost most, if not all capacitance resulting in poor
transmit signal especially in audio circuits. So I would carefully check the
resultant voltages after reforming and replace any caps in audio circuits,
especially the cathode by-pass caps first.

Then keep a very close eye on the power supplies for ripple.  Considering
the prices of capacitors versus finding and replacing transformers and
chokes, they are very cheap to replace in the beginning.

Have fun with the Johnson.

73  Jim
de W5JO





More information about the AMRadio mailing list

This page last updated 23 Oct 2017.