[AMRadio] Johnson viking 2..


Peter Markavage manualman at juno.com
Wed Jul 28 18:31:03 EDT 2004


An additional point. Flipping the power switch "ON" on the Viking II, and
a number of other rigs, only turns on the low voltage supplies. Using
Geoff's procedure will not tickle (reform) the capacitors in the high
voltage supply which only is activated when the Plate switch is flipped
on. Pull any tubes that get this high voltage, flip the plate switch (HV
switch or whatever it might be called), and then proceed with the
capacitor tickle.

Pete, wa2cwa

On Wed, 28 Jul 2004 15:03:00 -0500 "Jim Wilhite" <w5jo at brightok.net>
writes:
> 
> ----- 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

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