[AMRadio] Cable splitters for receivers


Geoff ars.w5omr at gmail.com
Sat Jan 11 15:03:48 EST 2014


On 01/12/2014 01:04 PM, Donald Chester wrote:
>
> I once used two receivers, a 75A-4 and a R-390, just by connecting the 
> same transmission line to both receivers using a T-connector. It 
> didn't seem to attenuate either receiver's signal level noticeably. 
> The greatest danger in doing that is that spurious products from one 
> receiver will show up in the other.
>

I did that same thing with a pair of Hallicrafter SX-73's (R-274-D) and 
what I noticed was, that trying to peak the 'Antenna' tuning on one 
receiver, detuned the other.

I'm going to ass/u/me that the input impedance on the Hallcrafter SX-73 
is ~50ohms, simply for the mere fact that they are fed via SO-239's.

So, approx 25ohms at each receiver is pretty low - about half of what 
they're looking for.

That's a fairly low impedance, but to have the tuning of one affect the 
other was unexpected.  Perhaps a 2:1 transformer, and parallel each on 
the secondary may have eliminated that phenomenon.


-Geoff/W5OMR



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