[TMC] VOX-2

[Telegrapher at att.net]

Couple of things i've noticed in playing/working on this unit.  

1: I was complaining about the excessive amount of leakage  from the unit.  When operating on 40 meters here, 7293 in the daytime, the signal on the receiver when in the receive mode was running almost S-7 and really was causing problems hearing other stations.  I found that by turning the "XTAL" switch at the bottom of the front panel from "VMO" to "1" or other position that the leakage from the unit went almost to zero.  Not really discernable on the R-388 anymore.  makes listening to on channel stations a heck of a lot easier. Just a quirk that i found that out.

2: Drift.  I initially felt that this was quite stable, however never such as todays digital communications could be used with it.  Tonight while giving a lot of thought to the problems being faced, while having the HP Freq counter hooked to the HFO output and watching the frequency, i switched the "XTAL" switch from postion 1 back to VMO.  WHAT!  There was a 63 cycle shift in the frequency.  Not sure why that's happening because all three of the HFO outputs on the panel have some sort of termination on them.  One to the Counter, one to the GPE exciter and the third has a termination on it.  It happens every time i change the switch position so it's not just a fluke occurance.  However, the frequency can be reset to whatever you want it to be, in this case 3645.5 Kc with the Calibrate control.  Drift today has been mainly in the downward direction but i had powered the unit off last night so it may not be fully warmed up yet.  Constant monitoring will tell me if it stabilizes.

3: Output.  I've been able to get up to about half scale watching the "HFO" output.  Way more than needed as i only use .2 mc to drive the GPE-1 exciter and that is more than adequate.  Some new tubes cleared that up but according to the manual .9 ma should be the norm.  May be something to that, will have to investigate.  

4: Ovens.  My Outer Oven light remains on constantly.  But i believe it's tied to the inner oven problem.  I am measuring one of the inner oven loops open and did indeed find some open wires where corrosion  and some sort of short to the case hd opened he loops.  Fortunatly it is right on top of the case.  I cleaned the wires, and they are indeed fine wires, and tried to solder them back together.  Well it didn't make any difference so i'm not sure that the repair job worked.  All the rest of the Oven circuitry appears to be in order.  Like to get this working just so i can say it works.  Composure of the wires i'm not sure of so a solder repair not be applicable to them.

Anyone else playing with a VOX unit?  This is a pretty nice clean unit.

Larry
W0OGH