[Boatanchors] 51J's vs R-338's?

[WA5CAB at cs.com]

Brian,

For the filter center freq. you need to look for numbers on the actual filter 
I would think.  Then you will probably find it on the list someone else 
pointed to.  353B-60 being the part number of the complete plug-in assembly.  The 
bandwidth is 6.0 KHz of course.

I'm not an expert on the intricacies of Collins in-house model numbering 
standards but if this one follows the numbering schemes they used for 
transmitters, receivers and transmitter-receivers, the 353 means "Mechanical Filter 
Plug-In Adapter" and the letter "B" identifies the set it was built for.  And I 
haven't a clue as to what that was, as the letters were mostly assigned 
chronologically but with exceptions.  All I can say for certain is that the buyer told 
me that 653C-nn was for the 75A-1 (I once had a 653C-31).  Whether the 51J-1 
used "C" also or had its own letter I don't know.  But odds are the vintage of 
yours is around the time of those two.

In a message dated 11/8/2005 4:40:35 AM Central Standard Time, 
brianclarke01 at optusnet.com.au writes: 
> Hi Al,
> Thanks for the lead. Not a single 522 - number there at all - not even the
> one that started my query.
> I suspect the reason for this is that the item I have is called a Mechanical
> Filter Plug-in Adapter Type No 353B-60. It looks like it is meant to replace
> a normal B7G tube, perhaps near the end of an IF chain? Perhaps like the
> Bill Orr article suggesting replacing a 6BA6 with a 6BE6. But for what
> centre frequency?
> 73 de Brian, VK2GCE.

Robert Downs - Houston
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