[R-390] 390 collins radio adapter ant. input adapter network

[Bob Camp]

Hi

The only use I can think of for the adapter you have is for doing a  
common mode rejection test. That of course assumes it's for an R-390  
at all.

The best way to hook things up:

Put a transformer primary between the two pins of the coax balanced  
conector.

Put the transformer secondary between the N connector center pin and  
ground via a common mode choke.

Isolate the ground on the radio from the ground on the N connector.

That way the crud on the local radio ground does not show up on the  
antenna input.

Bob

On Nov 15, 2007, at 6:50 PM, Rasputin Novgorod wrote:

> Hi guys:
>
> I recently won a couple of "r390 collins radio adapter
> antenna input adapter network" eBay Item number: 140172485081,
> for $10 each. They are beautifully made, silver plated;
> must have cost someone a lot of money.
>
> Basically they are a cylinder with the Coaxial Balanced
> connector on one end, and an N connector on the other. The center
> pin of the N goes thru a capacitor to ~both~ pins of
> the coaxial connector. The center pin also goes thru
> a 50 ohn resistor to ground. It's not a connector adaptor,
> it's some sort of test jig.
>
> 1) Anyway, I plan to rewire one of these to be a connector
> adaptor; to go from my coax from a random wire, to the 390a
> balanced antenna input. Looking at the 390 from the back,
> I seem to remember that the N connector's center pin should go
> to the Coaxial left pin, and the right coaxial pin goes
> to the connector shell (ground). The 50 ohm resistor will
> be removed. Should I remove the capacitor, or leave it in
> as a DC block? Have I got it right?
>
> 2) What was this part originally used to test for? Is there
> any reason to keep my second adaptor original so I can do
> this test? If so how is the test done?
>
> Sincerely
> /b
>
>
>
>
>       
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