[Johnson] Reality Check please!

[Rodger]

Hi Dick,

If you have any external receiver/transceiver that covers the actual VFO 
frequency range which is 4.9-5.5 Mhz. I would use that to pick up the 
VFO directly for calibration purposes.  You won't need to connect its 
antenna to anything, just place a lead near the VFO.  The VFO does tune 
"backwards", the low end of the band is tuned with the VFO set for 5.5 
Mhz and the high end of the band will be covered with the VFO 
oscillating at 4.9 Mhz.   For example on 80 meters, the 9 Mhz. IF mixed 
with the 5.5 Mhz. VFO signal results in a difference frequency of 3.5 
Mhz.  At the high end of the range, with the VFO oscillating at 5.0 Mhz 
the difference will be 4.0 Mhz.  Even with a couple of lab grade scopes 
and a high end signal generator I think that often the most useful piece 
of gear on my test bench is a little Grundig YB-400 receiver with push 
button frequency entry that covers up to 30 Mhz and allows quick checks 
on the health, stability, tone, and frequency of the various oscillators 
and mixers without ever hooking up a test lead.

I don't have an Invader 2000, congratulations on a neat transmitter!  
The actual sideband and mixer circuitry is very similar to the external 
SSB adapter I have that is styled to go with a Valiant 2 though it works 
quite well with my Valiant 1.

Good luck on getting this nice rig going again.

73, Rodger WQ9E



Dick wrote:
> I don't think I'm in Kansas anymore.  While I've never claimed to be 
> an expert technician or troubleshooter I have a modicum of experience 
> in electronics (45 years as a ham)  but have a problem that has me 
> bewildered.  Here's the situation:
>
> Rig is an Invader 2000.  I am trying to align the VFO.  According to 
> the manual I am supposed to couple a  "detector" capable of covernng  
> 3550 to 4050 kc (khz) to pin 1 of V8 (the second mixer).  After tuning 
> the transmitter to 4050kc I should be able to adjust L8 to "zero 
> beat".  Well, I can only get it down to about 4600kc before it starts
> to go up again.  Additionally, tuning the transmitter down towards 
> 3550kc,  the frequency actually goes up!  In stead of using a 
> "detector" (they actually mean receiver I think) I am using a 
> calibrated frequency meter hooked to pin1 of V8.  That shouldn't make 
> any difference, right?  I have replaced all the caps in the VFO (a 
> real pain) and all the resistors for V4 (the VFO tube) all to no 
> avail.  All grounds have been resoldered/re-riveted.  All coax in the 
> VFO has been replaced along with the VFO tube itself (6AU6).
>
> What am I missing or not seeing?  I'd really like to get this old gal 
> back on the air but I am about to really start using this thing as a 
> "boat anchor" unless I can find a solution.  All you experts out 
> there.....PLEASE HELP!!!! Thanks in advance.
>
> 73's
> Dick
> WA6UBJ
>
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