[Hammarlund] PTT for the HX-50

[Duane Fischer, W8DBF]

Bob,

Ah yes! Now that you mention it I do vaguely recall when Hammarlund 
announced this new option. Unfortunately the engineer sneezed while drawing 
the diagram for the circuit and the line zigged when it should have zagged. 
When the operator keyed the hand mike it did activate the PTT, mute the 
receive and activate the transmit relay circuit. Unfortunately it not only 
muted the receive audio, but also the operator! If I remember correctly, 
(Cough. Clearing pipes.), the engineering department was seriously 
understaffed due to tech's keying the hand mike, having their eyes cross 
like those dual needle meters do, their hair standing up like they got 
goosed with a cattle prod, colored sparks shooting out of their ears and 
then being vaporized leaving only their rubber soled shoes behind. After the 
fourth tech testing the transmitter went permanently horizontal, somebody 
decided to doublecheck the wiring diagram for the PTT circuit. Hence the 
term "dead short" was coined!

Thanks for posting Bob, you probably saved a few lives by doing so.
----- Original Message ----- 
From: "Robert Nickels" <w9ran at oneradio.net>
To: "Duane Fischer, W8DBF" <dfischer at usol.com>
Cc: <hammarlund at mailman.qth.net>
Sent: Sunday, March 05, 2006 12:51 PM
Subject: Re: [Hammarlund] PTT for the HX-50


> Duane, they may call it the Drifty 50 but just for the archives, I should 
> report that the VOX circuit isn't as nifty as I thought yesterday.  Al's 
> schematic is marked "Production Run 2" which evidently includes some 
> changes in the VOX relay circuit as my HX-50 s/n 518 is wired differently. 
> My previous comments about wiring a PTT switch to terminal 2 on the rear 
> panel is correct in both cases, but the version I have requires two 
> separate wires to the switch, which precludes the use of a standard 3 wire 
> mic plug.  Also there is 120 volts DC on the PTT circuit, not what I want 
> to hold in my hand - so my advice to anyone playing with an HX-50 is to be 
> aware of these differences to avoid a shock hazard.
>
> 73 Bob W9RAN
>
>
>
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