[Johnson] Ranger Tx Working - At Last

[Michael Hardie]

First of all thanks to the many folks who sent me advice, the Ranger is 
finally working "OK", I'm not 100% satisfied, signal reports are good both 
phone and CW.

Problem #1 - the large slider resistor (R35?) had been replaced with one 
that was physically bigger than the original having two results, it wasn't 
secured to anything so its terminals could come into contact with the 
chassis and the drive pot had been replaced with a physically tiny one to 
accommodate it.  I suppose that in conjunction other problems or maybe 
working on the bench a nasty surprise could have happened, fortunately both 
these conditions were easily visible and correctable.  Problem #2 was 
brittle and cracked insulation on the HV choke and transformer leads, this 
caused a short to ground inside the HV choke end bell which resulted in the 
HV rectifier tube plates glowing red very shortly after the Tx was switched 
on.  Apparently brittle insulation on the leads is a common Ranger problem 
and the usual fix is to put heat shrink tubing over the leads.  With this Tx 
moving the leads even slightly resulted in the insulation breaking and 
falling off, so the choke and transformer were taken out of the chassis (A 
big job) then the end bells removed from the choke and transformer.  The 
leads were clipped close to where they entered the windings, new leads 
installed, (Correct colors) then heat shrink tubing put over the 
connections.  It was possible to shove the heat shrink down into the 
windings slightly.  Longer leads were put on the HV choke so that it was no 
longer necessary to connect to the terminal strip, they went straight 
through to the rectifier socket.  Problem #3 was that many of the .005 caps 
had been replaced using a variety of values, these were removed and replaced 
with .005's @ 1KV, in most cases by clipping the cap leads close to the cap, 
bending the short wires into a hook shape so the new cap could be 
mechanically fastened to the hooks, then soldered.  The "hot" end of the 
modulation transformer feedback winding had been moved to ground, (Result 
was that both ends of the feedback winding were grounded) after moving the 
"hot" end to the correct place problem #4 occurred - strong oscillation as 
soon as "PHONE" was selected.  This could occur in a DX-100 if the plate 
leads to the modulator tubes were reversed, sure enough they were in the 
Ranger, easy fix, move the leads where they should be, result was no more 
oscillation.  Problem #5 - the parallel triple 33K resistors connected to 
the clamp tube socket (effectively 11K) had been replaced with one huge 16K 
resistor, the type that bolts onto a chassis for heat sinking, and of course 
it was dangling loose on the connecting wires.   Why 16K?  My assumption was 
that it was the resistor on hand so it was removed and one 11K 5 watt 
resistor installed.  Problem #6 - several connections to the function switch 
were not even close to what the Construction Manual indicated they should 
be.  At first I thought there might be burned contacts on the switch and a 
previous owner had made the necessary changes, but this wasn't the case, the 
switch contacts were fine.  The various wires were put back where the manual 
indicated they should be.



Voluntary Changes.  As acquired the Tx had a press-to-talk mod that was done 
according to the instructions in the Operating Manual, but this meant there 
was about 110 volts on the mic switch - maybe not good with my homebrew push 
button mic switch, plus the voltage divider configuration to get the 110 
volts must have produced a lot of heat under the chassis.  The old relay, 
power divider resistors and associated wiring was removed and a 12 volt 4PDT 
relay installed.  A small voltage doubler circuit using dial light power was 
used to power the relay via a 33 ohm resistor.  With a the 3rd set of relay 
contacts it was possible to wire the red transmit light so that operating 
PHONE the light only comes on when the press-to-talk is depressed. 
(Continuously lit when "CW" is selected - the 4th set of contacts were not 
used)  The modulator tubes were swapped from 6L6's to 6L6GC's. (No 1614's 
available yet)  I almost forgot, R3 the resistor inside the VFO compartment 
that reportedly overheats was replaced with a 5 watter, although there were 
no signs of overheating and the resistance measured normal.



Future Possibilities.  I really don't like making changes too far away from 
the stock configuration but...  does anyone know if biasing the 6146 grid 
has been tried?



Mike VE7MMH