[TMC] Early Version of TMC GSB-1

[triodes at optonline.net]

Hi Roy,
 
Thanks for the reply. No, there is no need to repaint or cosmetically restore this baby; she is pristine as-is! All it took was a little car wax to lightly freshen up the front panel and knobs, and to brush out the accumulated dust from the chassis.
 
The rear surface of the front panel of my GSB-1 is clear irridite/alodine. It is not painted, so it should make proper electrical contact with this rest of the chassis. Good to know of the possible issue of it not making intimate electrical contact, however.
 
The unit works as it should, both with my GPR-90 and my R-390. The only thing I did as a precaution was to replace the two 40/40 uf type-FP electrolytics in the power supply section.
 
I suspect that my unit is of very early production; probably around the 1955 time-frame, which I believe is when TMC introduced the GSB-1. The converter came with my GPR-90, and that unit is also very early production (I think the serno. is 1303), as it does not include the xtal calibrator feature that the later production units had.
 
I really would like to see if I can find the schematic to this particular rev. GSB-1, and to hear from any other owners who may have this version of the unit as well.
 
Best 73,
 
Bruce, W2XR


----- Original Message -----
From: Roy Morgan 
Date: Tuesday, July 28, 2009 1:18 am
Subject: Re: [TMC] Early Version of TMC GSB-1
To: triodes at optonline.net
Cc: tmc at mailman.qth.net

> 
> On Jul 28, 2009, at 12:40 AM, triodes at optonline.net wrote:
> 
> > I recently acquired a virtually as-new GSB-1 SSB Converter.... 
> 
> > significantly different from the first GSB-1 that I had.
> 
> Bruce,
> 
> I think your GSB-1 is a hoax and you should get rid of it as 
> soon as 
> possible. Just send it to me and I'll make a thorough analysis 
> of the 
> thing (which may take quite some time to complete).
> 
> 
> 
> I have a GSB-1 but it's not like the one you just got.
> 
> If yours is in good condition, you won't be tempted to 
> refinish the 
> front panel. But if you ever do, here's an odd thing that 
> happened to 
> me: I was overhauling a GPR-90 and GSB-1. The GSB-1 panel had 
> been 
> refinished, front and back. The thing did not align correctly, 
> and 
> drifted off frequency when your hand approached the panel, but 
> only 
> on Lower Sideband. I traced the trouble to this: The rear of 
> the 
> panel must make good electrical contact with the points it 
> mounts to 
> the chassis. The side band switch depends on the capacity of 
> the 
> panel to the chassis and good grounding to make the local 
> oscillator 
> shift frequency correctly. The switched-in capacitance to lower 
> the 
> LO frequency is grounded at the front panel by the switch. So 
> I had 
> to sand-paper the mounting points and make sure the grounding 
> was 
> right.. then it aligned and ran correctly.
> 
> Roy
> 
> Roy Morgan
> k1lky at earthlink.net
> 529 Cobb St.
> Groton NY, 13073
> Home: 607-898-3607
> Cell: 301-928-7794
> 
> 
> 
>