[Johnson] Viking Ranger VFO Problems/Access

[David Harmon]

Bill.....I totally agree with what Mark has said.
I have done the Chernobyl resistor replacement several times and never
removed more than the left side panel.
Also....I use a 5 watt wire wound tub resistor or metal oxide resistor for
replacement.
Mouser Electronics https://www.mouser.com/
Part number 286-18K-RC
You can cut the old resistor leads long....right next to the resistor then
put a hook on the old leads and the new resistor leads, crimp and solder.
Some guys put the resistor underneath the chassis but I put it in the
original location to keep the internal VFO heat to about the original
temperature to help avoid drifting.
Replace both tubes.


73

David Harmon
K6XYZ
Sperry, OK

-----Original Message-----
From: johnson-bounces at mailman.qth.net
[mailto:johnson-bounces at mailman.qth.net] On Behalf Of Mark Donaldson via
Johnson
Sent: Monday, July 22, 2019 9:26 AM
To: Johnson <Johnson at mailman.qth.net>; Bill Stewart <cwopr at embarqmail.com>
Subject: Re: [Johnson] Viking Ranger VFO Problems/Access

 Hi Bill,
You have just discovered the most common problem with Rangers, Valiants
etc., the so call Chernobyl resistor. I won't get into what is going on just
Google it. To answer your question, you only need to remove the left side
(as you are facing the front of the transmitter it will be on your left
side) side panel on the VFO, don't forget the nuts on the bottom side. I
have done several of these repairs and it can be done without further
disassembly of the VFO. If you remove the front panel you will risk breaking
the disk on the reduction drive.
73s,
Mark WA1QHQ
    On Monday, July 22, 2019, 10:13:19 AM EDT, Bill Stewart
<cwopr at embarqmail.com> wrote:  
 
 GM All,
My Ranger (manual dated 1954) VFO started drifting with key down no matter
how long the warm-up is, so I took the top off the VFO compartment and found
the OB2 to have a large white, internal, spot at the top of the tube. Also
the area around the hole, in the phenolic board, where the tube goes thru,
is charred and cracked. 
Obviously a lot of heat was there for a while. Also in a short check, with
the power on, a lot of flashing inside the OB2 and it gets very hot. I
suspect that R3 has changed value drastically. I was able to remove the side
plate on the VFO and can see that R3 is cracked. Now the main question is
does the front panel have to come off to get the VFO box off (I'm suspecting
it does) . All the bottom nuts are off and only the shaft is keeping the box
from coming off. I have taken the VFO dial off and am down to a large nut.
Just wanna make sure before I get into what looks like a real P-I-B job. 

A bit more to the story. This Ranger has the keyer mod and the xmtr was a
kit. The wiring technique is not all that good. The xmtr worked good for a
while after I got it. But the keyer began to need adjustment. I could not
get the adjustment needed and looking at the keyer wiring, decided to rewire
it. The keyer worked. The drifting started after the keyer rewiring. Maybe
coincidence or did I foul up something?? 

If I ever get the VFO box off, I will cut a slot in it's front so it will
slide off over the VFO shaft. Don't recall having this issue when I went
into the Navigator VFO. 

Tnx for any tips, suggestions, etc. 
73 de Bill K4JYS
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