[Boatanchors] Johnson Ranger VFO Access Question

Fri Dec 27 19:14:19 EST 2013

Oh boy, Scott -- you have picked a rather tedious but not impossible 
project.  I just got my Ranger back together last week so it's fresh in my 
mind.  It is pretty obvious what needs to be done, but one somewhat major 
caution follows:

Yes, the front panel must be removed to get full access the interior of the 
VFO. However, the following is important prior to panel removal:  There is a 
hole in the chassis through which a small, long shaft, flat-blade 
screwdriver can be passed to access the set screws on the flexible coupling 
which connects the front panel reduction drive to the VFO capacitor. Be sure 
to get those properly loosened (the ones which contact the shaft of the 
reduction drive) before you remove the panel.  Over the years the heat in 
the VFO box will have taken its toll on the micarta material in the 
coupling, making it very brittle. Use extreme care when disengaging the 
reduction drive from the coupling-- even a seemingly minor sideload may 
cause that thin "flexible" phenolic/micarta portion of the coupling to 
break.  Loosen the coupling nut from the panel after all other stuff is 
loose and keep it steady and in place with one hand while removing the panel 
with the other. I found it most advantageous to let the panel hang over the 
front edge of my bench and work it off gently while holding the reduction 
drive steady.

OK, so you did all that but still broke the coupling.  It happens. Save the 
pieces!  A replacement coupling is hard to find because one end  accepts a 
1/4" shaft (the reduction drive) and the other end a 3/16" shaft (the 
capacitor). Have no fear -- it is relatively easy to repair.  JB weld is 
your friend, or some folks have used RTV to effect a repair. You'll see what 
is necessary when you have the pieces in your hand.

While you have the VFO apart, you might as well remove the 18K series 
resistor for the VR tube and put it in a convenient place under the chassis. 
Most of the Ranger gurus recommend this, although I did see a dissenting 
article which argued that keeping it nice and hot in that compartment added 
to the (eventual) VFO stability. Whatever is your pleasure, I guess, on this 
one.

Reassembly procedure will be obvious, keeping in mind the logical order of 
assembly so that you have access to the two  screws at the front of the VFO 
box before you put the panel back on. Yes, getting at those flex coupling 
set screws is a genuine PITA -- a strong light source aimed at the front 
hole will help you to see the screws though the bottom access hole. Also, I 
found that the easiest way to get the phenolic calibration cap extenders on 
place was to remove the top c-clips, set all 5 in place and jockey them into 
the holes with an awl or dental pick as you put the cover in place, then 
reinstall the c-clips.

You may decide that the preceding is a lot of unnecessary work and that 
enough access will be afforded by removing just the side panel. Wouldn't 
blame you a bit if you choose that option. My unit was complete with died 
mud and some corrosion, so I wanted to get at the whole interior of the VFO 
for cleaning.

Hopefully others will chime in with additional/alternate ideas and 
experiences. Enjoy!

73 de Stu, W7FE

----- Original Message ----- 
From: "Whitebear1122" <whitebear1122 at comcast.net>
To: <johnson at mailman.qth.net>
Cc: "boatanchors" <boatanchors at mailman.qth.net>
Sent: Friday, December 27, 2013 3:01 PM
Subject: Re: [Boatanchors] Johnson Ranger VFO Access Question

>
>
>> The one time I was in a Johnson VFO was back around 1996 when I had to 
>> get into my Valiant VFO cabinet to replace both tubes and the charred 18K 
>> VR current limit resistor.
>>
>> Today I'm looking inside my Ranger VFO.  I was given this Ranger by an SK 
>> last year. It had sat on his floor next to the operating desk since at 
>> least 1970.  It looked horrible, corroded, and I know he had a mouse 
>> problem it the shack.  Imagine my surprise when I took some GOJO to the 
>> cabinet and front panel and it cleaned up to an 8 out of 10.  It was 40 
>> years of floor grime, not corrosion after all.   I opened it up and the 
>> insides look like new other than a bit of grime.  No mouse scat at all. I 
>> need to recap the electrolytics of course.  I powered it up this 
>> afternoon and it works for the most part, good power output, but the VFO 
>> is jumpy by several hundred cycles, not sure if it's mechanically induced 
>> or what.   Tuning the main tuning suggests it may be mechanically 
>> induced.
>>
>> I would like to open up the VFO to retighten all the screws and nuts, put 
>> a little DeOxit on the variable capacitor, and make a few measurements. 
>> I removed the side of the vfo cabinet.  Oh my gosh, I had forgotten how 
>> tight things are in there.  If I want full access to the vfo, I need to 
>> remove the top.  There are screws holding the top to the sides along the 
>> front panel side so I can't get at them.  Looking at it, I'm wondering if 
>> the only way to get good access to the VFO for mechanical tightening is 
>> to completely remove the front panel.  Wow, that sounds like a huge 
>> effort!
>>
>> How on earth do you get good access into that VFO cabinet without 
>> removing the front panel or is it even possible?
>>
>> 73, Scott WA9WFA
>
> ______________________________________________________________
> Boatanchors mailing list
> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Boatanchors at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html 