[MRCA] Identify Strange Item

[Tom B]

Hi Ray,

Regco made a ton of this stuff too.  WJ also made tunable demodulators 
for this purpose.

Tom Bryan
N3AJA


On 3/16/2021 3:57 PM, Ray Fantini wrote:
>
> Speculation, it’s a receiver that would have been used to decode 
> subcarriers on microwave and satellite transmissions. In the old days 
> before everything went to digital common carrier microwave and a lot 
> of the old C Band satellite traffic carried subcarriers although most 
> I remember were at higher frequencies, it was common to use both 
> USB/LSB and have a different conversation on each sideband.
>
> The weird thing was I always thought WJ had a lock on that business 
> being there were tons of there stuff for decoding subcarriers, don’t 
> know why but think most common carrier microwave used USB/LSB where 
> the Satellite stuff was FM.
>
> There are a lot of the selective voltmeters that are floating around 
> on the surplus market that were used for setting the injection level 
> of subcarriers on microwave channels back in the common carrier days 
> but all the common carrier technology is long gone today.
>
> Ray F/KA3EKH
>
> *From:* mrca-bounces at mailman.qth.net <mrca-bounces at mailman.qth.net> 
> *On Behalf Of *Doran Platt
> *Sent:* Tuesday, March 16, 2021 3:34 PM
> *To:* mrca at mailman.qth.net
> *Subject:* [MRCA] Identify Strange Item
>
> CAUTION:This email originated from outside of Salisbury University. 
> Please exercise caution when clicking links or opening attachments 
> from external sources.
>
> My friend brought over a piece of gear that I cannot identify, nor 
> fathom its actual end use.  He picked this, and an Eico novice tx at a 
> junk store. Its is nomenclatured as "Transistorized Channel Selector" 
> and apparently mfg by NSA's lab.  AC powered, 8 1/2" high rack mount 
> assy.  It has a 5 band, slide-rule dial assembly not unlike an 
> Eddystone or National (but not). The 5 bands go from 0-100 kHz.  It 
> has a BFO selector USB, LSB, and AM, input and output gain conbtrols 
> and a.c. power switch.  No other controls.  There is a nice schematic 
> inside that tells it all... if one knew what it was really used for.  
> It has a single LPF input via 1/4" phone jacks. There is a 5 band LO 
> going to a balanced mixer, thence to a Collins 455 mech filter. Signal 
> then goes thru a 455 kHz strip, a diode detector and crystal 
> controlled BFO for USB and LSB.  Again, no front-end gain, no AVC, or 
> pre-selection.  Input sensitivity to get a usable signal in the 
> headphones is above perhaps .1v Anyone have any idea?  Maybe a back 
> end for a VLF receiver system?
>
> Jeep K3HVG
>
>
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