[Milsurplus] WTB: PRC-1099A Channel Switch

Al Klase al at ar88.net
Tue Jul 28 19:31:08 EDT 2009


Hi Mark,

Thanks for the response.  I emailed an RFQ to Datron last night, but 
haven't yet had a reply.  The 85 bucks is kinda what I expected.  I'm 
glad you confirmed that it was a custom part.  That will save me beating 
the bushes further.

It appears that a standard 12-detent switch will match up with the front 
panel artwork.  So I'm going to look into using a single pole switch and 
a diode matrix (15 diodes) to produce BCD.  The switch feeds CMOS inputs 
with pull-up resistors, so it should work.  I'm assuming it's straight 
low-active BCD.  My switch is sufficiently messed up that it's hard to 
be positive.  (The manual is available for download from American 
Milspec for 10 bucks.  Instant gratification is a cool thing.)

The "A" version has an entirely different synthesizer, based on DSS.  So 
I hope it's an improvement.  By the way, this set is labeled PRC1099 on 
the outside, but I found another tag inside after I bought the wrong 
manual.  The give away is extra indicators below the numbers on the LCD 
that say things like "SCAN", "OPT", and "DATA"

Does anyone know how to identify what options are installed in these 
things?  I'd especially like to have AME, which doesn't seem to be the case.

Regards,
Al

Mark wrote:

Howdy Al,

It seems every mil radio has some sort of drawback, wart, pain in the 
backside, whatever.  The 1099 is not immune.

It's really not a question of whether the original Grigsby (now 
Electroswitch) channel switch will fail, but when.

To be slightly fair to Transworld/Datron, I doubt if they thought their 
original switch would still be in operation after 20+ years.  That's a 
lotta cycles.  It's still annoying when they fail.

After the switch on my original set began to get ragged, I searched for 
a LONG time for a replacement.  It has direct BCD readout and was 
custom-made for Transworld.  Electroswitch was still honoring their 
agreement with Transworld and would not sell me a replacement directly; 
they said I had to go through Datron.

Datron had since replaced the enclosed switch with an open-frame unit, 
and the cost was something on the order of $85.00.  Ridiculous, I said 
and continued my search.  Came up with zilch, zero, nada.

I even worked up a decoder circuit that would convert the outputs of a 
standard 10-position switch to BCD.  When I realized how much time and 
trouble it would take to do that, I just bit the bullet and ordered the 
blasted thing from Datron.  Chalked it up as one of things I just have 
to do to maintain availability of a radio I really like. Ended up 
getting about half a dozen in the same order (five for various other 
people; they've been distributed).

So that's your choice I'm afraid: NO choice, order from Datron.  But at 
least the current switch looks like something that will hold up, and can 
be cleaned with De-Oxit if necessary.

My old Grigsby switch has very rough detents, but still works for the 
most part.  So I'm keeping it for a last-ditch spare instead of drilling 
it to see what went wrong.

--Mark Francis
   KI0PF

> Message: 5
> Date: Tue, 28 Jul 2009 00:14:28 -0400
> From: Al Klase <al at ar88.net>
> Subject: [Milsurplus] WTB:  PRC-1099A Channel Switch
> To: milsurplus <milsurplus at mailman.qth.net>
> Message-ID: <4A6E7B24.7030003 at ar88.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> 
> I find myself in need of a channel select switch for a Transworld/Datron
> PRC-1099A, Part number: 510028.  Same part is used in the PRC-1099.
> 
> Any help appreciated,
> Al
> 

-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/


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