[Johnson] Need Info on Johnson Viking Ranger 12V PTT Circuit and other improvements

Michael Hardie mike46 at shaw.ca
Thu Jun 4 11:46:37 EDT 2009


Joe,

I don't have the exact information you requested but homebrewed a 12 volt 
PTT relay installation using the dial light voltage through a voltage 
doubler/resistor circuit for power.  If you're using the older Amphenol 
style 2 pin mic jack you'll need the type of doubler circuit that has one 
side of the output grounded.  The actual PTT connections to the mode switch 
were as per the Ranger Operator's Manual but with a 4PDT relay (One set of 
contacts not used.) it was possible to have the red transmit light only 
illuminate with the PTT pressed. (When in the AM mode, CW mode same as 
before.)  If there's interest I could make photos of the schematic and 
installation and email them, uploading something to the archives is way 
beyond my capability.

The 12 volt PTT relay mod has a couple of real advantages, you can rotate 
the mode switch all the way to standby without transmitting and there's no 
"high" voltage on the mic.

About 6 months ago I acquired my Ranger.  It had a dead short inside the HV 
choke that turned out to be caused by the insulation cracking off one of the 
leads and the bare wire contacting the choke's end bell.  Brittle insulation 
on the choke and transformer leads due to aging is a common Ranger problem, 
so if you don't intend to do major renovations be very careful around these 
leads.  Apparently it's a common fix to install heat shrink tubing on all 
the leads, I ended up removing the HV choke and the power transformer and 
replacing each lead with new wire.  For me this was a big job.

The HV and LV electrolytics in this Ranger were OK.  The "+" lead on each 
was unsoldered and they were individually connected to a reforming jig, but 
actual reforming wasn't necessary because the leakage was a fraction of a 
milliamp.  Various caps in the modulator section had been changed to values 
that were about 10 times original, these were all removed and replaced with 
caps that were as close to original values that modern components would 
allow.  Also this led to downloading a Ranger construction manual and 
checking all the wiring which turned up many incorrect connections.  The 
feedback winding on the mod transformer had been intentionally shorted to 
ground, after unsoldering and removing the short the reason became apparent, 
huge continuous oscillation as soon as the AM mode was selected.  The 
problem turned out to be that the connections to the two 1614 plates were 
reversed. (Suspected this from DX-100 days)  The two electrolytic caps under 
the small subchassis were leaky and were replaced with one 30 uF cap.

Several of the disc caps and the 11K resistor near the clamp tube had been 
replaced with a variety of oddball valued components, so they were removed 
and proper value components installed.  I haven't yet changed the power cord 
to a modern 3 wire one with a fuse in the chassis, but this is a very good 
idea from an operator safety stand point.

Probably more information than you wanted, good luck with your Ranger.

Mike VE7MMH 



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