Topband: RX input impedance

[Tom Rauch]

Hi Ford,

> I just used the Autek VA-1 to measure the input impedance of the
> receiver port on my IC-746.

The results might not be accurate. The VA-1 can overload the RF 
stage, and that will normally change the impedance.
 
> My question is, do I care?  More important, should I care?

I care here, because:

1.) I use narrow selectivity and external noise power is directly 
proportional to BW.

2.) I use splitters, and they must be somewhat correctly terminated 
terminated or one receiver "hogs signal" and will change the level in 
other receivers.

3.) I already have a marginal change in noise when I remove the 
antennas and replace them with a termination during some 
operating conditions when I expect to operate.

You might not care.

73, Tom W8JI
w8ji@contesting.com


--
FAQ on WWW:               http://www.contesting.com/FAQ/topband
Submissions:              topband@contesting.com
Administrative requests:  topband-REQUEST@contesting.com
Problems:                 owner-topband@contesting.com