[Johnson] Rebuilding Johnson Navigator ???

Gary Schafer garyschafer at comcast.net
Wed Jan 24 15:24:08 EST 2007


I wouldn't be too quick to replace any of the capacitors in the vfo circuit
unless there is obvious signs of them being bad. Not sure about the Johnson
vfo's but most have temperature compensating capacitors that were chosen to
minimize drift.

73
Gary  K4FMX

> -----Original Message-----
> From: johnson-bounces at mailman.qth.net [mailto:johnson-
> bounces at mailman.qth.net] On Behalf Of Jim Brannigan
> Sent: Wednesday, January 24, 2007 9:22 AM
> To: Freeberg, Scott (STP); Michael Crestohl; johnson at mailman.qth.net
> Subject: Re: [Johnson] Rebuilding Johnson Navigator ???
> 
> I would also take a hard look at the fixed capacitors in the VFO circuit
> and
> check the values of the carbon resistors.
> The original siver mica "postage stamp" capacitors in a Ranger (same VFO)
> were leaky.
> It is so difficult to get at the VFO, that you want to do it right the
> first
> time.
> 
> Jim
> 
> > If the Navigator has the same vfo as the Ranger, Valiant, Pacemaker,
> 500,
> > the only thing I'm aware of is the dreaded 18K current limit resistor in
> > the VFO compartment.  The part is grossly under rated and can eventually
> > decrease in value, going into a power death spiral :)  Really.  My
> Valiant
> > experienced that.  When I removed the resistor, it was measuring 50 ohms
> > on the ohmmeter.  That new value resulted in the Valiant blowing fuses,
> > damaging the 6AU6 vfo and OA2 regulator, and I'm darn lucky the low
> > voltage transformer didn't blow out.   The solution is to replace it
> with
> > a 4 or 5 watt part.
> >
> > Good luck with the Navigator.
> > 73, Scott WA9WFA
> 
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