[Heathkit] Looks like a D104 Project Cont.

[Robert & Linda McGraw (K4TAX)]

With all this discussion, keep in mind that there is more than one type of 
Astatic G-Stand.  The early ones {original G stand} had basically a single 
pole double throw SPDT switch associated with the PTT bar.  One pole took 
the PTT line to ground.  Without the PTT bar depressed this would be 
considered a N.O. or normally open contact.  The other set of contacts were 
N.C. which were used to short the audio line to ground thus preventing a big 
kerchunk when the PTT bar was depressed.

Then comes along the pre-amp base.  This is the T-UG Stand.  Here a couple 
of other contact arrangements were instituted.  There were several wiring 
conventions used.  Of course one was to turn the pre-amp on and off as the 
PTT bar was depressed.  Now it becomes more complicated as some of the 
contacts were make before break and some were break before make.  This 
allowed the DC to be applied to the amp, the amp settle before the PTT line 
was activated and lastly the audio output of the preamp was connected to the 
mike cable.  And then of course the option of grounding the audio line in 
the cable.  This of course prevented VOX operation and now enter the R and E 
switching configuration.

Here is about the most complete source of reference data that I've found. 
It is nicely presented too.
http://www.qsl.net/wa2mzf/d104.html

Note the wiring data on Page 2 information and the fact that there are 3PDT 
switches associated with the PTT switching.  Also note the schematic showing 
which contacts/wire colors are associated with the make before break and 
break before make switching as shown with the file Second G Stand.

Hope this helps.

73
Bob, K4TAX


----- Original Message ----- 
From: "Ron Youvan" <ka4inm at tampabay.rr.com>
To: "h" <heathkit at mailman.qth.net>
Sent: Wednesday, February 14, 2007 7:55 PM
Subject: Re: [Heathkit] Looks like a D104 Project Cont.


>> I found that I am getting a short from shield to audio.
>> I think that this is the problem.
>> Should not be any continuity between those two.
>
>   You need to compare the resistance between the two
> pins and the meter leads connected together directly,
> on the lowest Ohm scale that the meter has, like X 1.
>   You should have around 50 or more Ohms, then press the
> PTT bar/button/key does it change?
> It should if the MIC is switched, which isn't always
> done, as it can cause a big kerchunk on the air if the
> mic switch doesn't occur before the PTT switch.
>   (it must be made that way to work reliably)
>
>> It shorts even without the PTT bar pushed in.
>
>   Many times the MIC is not switched, that eliminates
> the kerchunk problem and also allows the MIC to work
> with VOX.
> -- 
>    Ron  KA4INM - I think I could live on my pay if
> governments didn't take half!
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