[Premium-Rx] Info on Sunair F-1606/U (GSR-921) Pre/Post Selector?

Tue Jul 26 18:52:28 EDT 2005

I think you may be right... This is a rack-mounted unit about the size/shape of a RA69790 (4U spacing?).  The front panel has
two large knobs marked "coarse" and "fine", a 3-position switch selecting "coarse/fine/bypass",  a six (I think..) position band selector
switch (total spread of 2-30 Mhz), a hi/low gain switch, and an indicator light labeled "transmit".

I opened this critter up last night, and was a bit amazed by the design.  The coarse and fine controls drive 2 independent multi-gang
variable caps, but what intrigued me the most was that there were two motors, each of which drive what appear to be switched
tuned circuits via a collection of cogged belts and roller assemblies.  There does appear to be some sort of RF preamp board
on the input with what looks like a set of filters of some sort. The design looks, for lack of better words, very "expensive".

I have sent a request to sunair for more info, but haven't heard back from them.  If I can find a digital camera, I'll try to post a picture
of it somewhere where everyone who might be interested can take a look.

-al-

P.S. To the gentlemen who asked if I could check on the R2174B/URR (I seem to remember this is a VLF version of the RA6790)....
I checked the LOGSA site, but it only has 1 set of documentation on the -A variant (I believe this is the standard one (equiv. to the
6790)  most of us might have).  Unfortunately, it won't even let me download that without a user account (which I don't have yet).
If I run across anything, I'll drop you a private email note.  I mentioned this here, rather than in a private email, in the hope that
it will prevent anyone else on the list (or who reads the archives) from jumping through hoops for LOGSA access looking
for this, only to find it's not there.

-----Original Message-----
From: Ahmet Gundes [mailto:ahmet-m at usa.com]
Sent: Tuesday, July 26, 2005 17:39
To: Corda, Albert J CIV NSWCDD B32; premium-rx at ml.skirrow.org
Subject: Re: [Premium-Rx] Info on Sunair F-1606/U (GSR-921) Pre/Post Selector?

Hello,

I have a GSR-920 Receiver. It has a Preselector button hole (location lower left corner ) covered with a plastic cap.  The Preselector is not installed in mine. I think the preselector for GSR series is more of an internal unit then external. However I have seen some couplers/matchers that are used with the GSR-9xx transceivers. Perhaps what you got is more for transceivers.  It could even be an amplifiers who knows.  But perhaps you can contact Sunair, the manufacturer of the GSR-920 receivers and they can clarify the issue. I am not sure if there was a 921 though.  Most of Sunair equipment have the metal plate indicating model no and with their name on it. I guess they made HF equipment mostly for Army so all the older equipment i have seen were all olive drab color.

I'd be curious to know what you got. 

Regards,

Ahmet

Hey Guys, 
    I just picked one of these pre/post selectors up at a local hamfest. 
Seems to cover 2-30 mhz.  I don't know if it would be considered premium 
quality, but it does seem to be very well-built, and I am thinking of 
using it with my RA6790.   Unfortunately, I haven't been able 
to find a thing on it on the web.  I've checked the archives, the 
various surplus vendor sites, BAMA and the US Army LOGSA 
site, but no luck.  I did happen to find a picture of what may have 
been it's companion receiver on the RigPix database (although 
the receiver is labeled GSR-920, not 921 as on the Pre/Post selector) , 
but that's just a guess (It looks similar, in that it's rack-mounted, 
seems to be the same vintage and size, and both are very very green ;-) 

Does anyone have a manual or specs for this critter?  I've put a request 
for info in to Sunair, but no response as of yet. I'm a bit curious because 
the gentleman who sold me this unit indicated that it had very little/no 
gain, but he felt it was still operating correctly since he indicated it had no 
internal pre-amp. There is a switch on the front, though, that' is labeled 
"gain" with  hi/low positions. I am going to crack it open tonight and take 
a look. 

Pointers to any info would be greatly appreciated. 

-al- 
albert.corda at navy.mil 

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