[Milsurplus] bc-348 Antenna input impedance?

[Al Klase]

Hutch,

Let's call it high impedance.  Except on band one, the antenna is 
connected to the top of the input tuned circuit via a 50pF variable 
cap.  This is appropriate to make best use of the short antennas on 
aircraft.  These antenna have a quite low "radiation resistance" but 
it's effectively in series with a small capacitance.  That's probably 
the source of the low impedance myth.

At the frequencies we're talking about the loss of signal strength due 
to mismatch is generally not a big problem due to the inherently high 
noise levels compared to VHF.  If you do need a little more umph from a 
50-ohmish source, try a broadband transformer like the 1:9 un-un shown here;
http://www.skywaves.ar88.net/ANTENNA/N3FRQ_Baluns.pdf

Al

On 11/5/2011 1:12 PM, John Hutchins wrote:
> Group -
> Any one know the BC-348-R  antenna input impedance value?  I have read
> low but but roughly how low.
> Hutch
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-- 
Al Klase - N3FRQ
Jersey City, NJ
http://www.skywaves.ar88.net/