[Johnson] Ranger I problem

[Gary Schafer]

I have a viking 2 that needs to be repaired, one of these days, that has a
bad modulation transformer. At very low audio levels it works normal. But as
soon as the audio level is increased the slightest bit it arcs inside the
transformer. Testing it with an ohmmeter it looks like it is ok. It draws
lots of modulator plate current when the audio gain is turned up.
I substituted another modulation transformer to confirm the problem.

73
Gary  K4FMX

> -----Original Message-----
> From: Jim Brannigan [mailto:jbrannig at optonline.net]
> Sent: Tuesday, August 22, 2006 5:23 PM
> To: johnson at mailman.qth.net; 'Craig C. Heaton'; Gary Schafer
> Subject: Re: [Johnson] Ranger I problem
> 
> Thanks for all the replies....
> I checked the resistance of the driver and modulation transformer
> windings,
> it is very close to the measurements I took two years ago.
> It might be that the windings break down only under Hi-voltage.
> 
> Next step is to have someone else talk into the mic and use a wooden stick
> to isolate the "talk back" problem.
> 
> Jim
> 
> 
> > The resistance on each side of center on the primary won't necessarily
> be
> > the same. Its been awhile since I checked a good transformer so I can't
> > remember the difference but it can be in the order of 10% or so
> difference
> > from one side to the other. This is due to the different lengths of wire
> > on
> > each side of the primary. It takes more wire as the core gets bigger.
> >
> > Maybe they will tell you in the manual what the difference should be.
> >
> > 73
> > Gary  K4FMX
> >
> >> -----Original Message-----
> >> From: johnson-bounces at mailman.qth.net [mailto:johnson-
> >> bounces at mailman.qth.net] On Behalf Of Craig C. Heaton
> >> Sent: Monday, August 21, 2006 6:30 PM
> >> To: Jim Brannigan; johnson at mailman.qth.net
> >> Subject: RE: [Johnson] Ranger I problem
> >>
> >> Jim,
> >>
> >> Take a look in the manual and see if the dc resistance is listed for
> the
> >> modulation transformer. On the primary side each side to center should
> be
> >> the same, hope the manual gives values for both primary and secondary.
> >>
> >> I had talkback problems in a Johnson "500", Peter Dahl to the rescue.
> Had
> >> to
> >> buy a new mod tranny, the old one didn't have the same resistance on
> the
> >> primary (each side to center) and the secondary was out of spec
> (internal
> >> short).
> >>
> >> 73's
> >> wd8kdg
> >> Craig
> >>
> >> -----Original Message-----
> >> From: johnson-bounces at mailman.qth.net
> >> [mailto:johnson-bounces at mailman.qth.net]On Behalf Of Jim Brannigan
> >> Sent: Monday, August 21, 2006 3:00 PM
> >> To: johnson at mailman.qth.net
> >> Subject: [Johnson] Ranger I problem
> >>
> >>
> >> My Ranger was completely refurbed and has been working properly.
> >>
> >> I put it on the bench to reset the bias and keyer settings, while it
> was
> >> on
> >> the bench I finished the PTT wiring (ala Phil Salas and WA1HLR).
> >>
> >>
> >> While testing it, I noticed that one 6L6 metal modulator tube was
> running
> >> considerably hotter than the other (laser thermometer)  Substituting
> >> glass
> >> 6L6's showed a slight glow on the plates of the tube in the same
> >> position.
> >>
> >> Then, in AM,  the Ranger started to "talk" to me and I can't quite
> >> isolate
> >> the source.
> >>
> >> Resistance and voltage checks are OK.  Before I start to take it all
> >> apart,
> >> any ideas??????
> >>
> >> Tnx in advance,
> >>
> >> Jim