[Milsurplus] One more Eb*y find

[Bob W7AVK]

Group -

I seem to remember the unit ran at 450 - 500 mhz.  It was one of the 
first attempts at an automatic plane IFF system.  Used a single tube osc 
with tuned lines and a relay controlled slung that changed its frequency 
at known intervals.  The receiver front end was an acron tube mixer with 
a 40 mhz IF string.

A "code wheel" for the day was placed on the end of the shaft in 
dynamotor to allow change of the unit's ID.  The story goes before these 
units got to the field they were concealed because of concerns about the 
poor security of the system.  Each unit was built on a special magnesium 
chassis and had several small electrically controlled destruct charges 
installed.

Every 645 you find was new "in the box" as none were ever installed.

BTW - Many of these units found they way to ham use on 420 mhz, 
modulated osc service.  Who could say what mode, a bit of AM and FM.  :-)

Fun times in the old days....

73  Bob  W7AVK





Tom Norris wrote:
> It's a transponder, it's part of SCR-515, similar to the
> Navy ABA if I remember correctly. Wonder if this
> new-in-the-box unit still has it's self destruct charge?
> Yikes!!
> 
> Tom
> 
>> Plus a 645 parts rig in another auction.
>> What were these used for?  Freq?
>>
>> Mac, K2GKK/5
>>
>>
>>
>> ----Original Message Follows----
>> From: Tom Norris <r390a at bellsouth.net>
>> To: milsurplus at mailman.qth.net
>> Subject: [Milsurplus] One more Eb*y find
>> Date: Thu, 21 Oct 2004 10:18:11 -0500
>>
>> One more -- a BC-645 new in the box, item 2278450079
>>
>> Tom NU4G