[Amps] Relays

[John/K4WJ]

Alex,

Thanks for the explanation. I just dug out the original brochure and 
for receive specs it says

"RECEIVER LINE INSERTION LOSS: Guaranteed less than 0.6 db. Typical 
loss = 0.2 db"

I don't know how Doc Sheller, K8RR, made the measurements. He didn't 
mention noise. I wonder if he was aware of it.

73..de John/K4WJ

At 03:19 PM 4/2/2008, Alex wrote:
>.... I'll explain that noise point:
>In order to reduce the intrinsic resistance of the PIN diode, you have -
>especially with the BIG high power ones- to pass about 200mA or more through
>the receive diode in order to reach 1 ohms or so. With this amount of
>current , the junction generates noise which can be seen to raise the noise
>at the antenna terminal. In my job I had access to an HP noise figure meter
>and found about 0.5 dB increases.
>It really isn't much, when considering that an HF radio has a noise figure
>of about 10 dB but it's there! In an average location you probably won't
>notice it, but it's there.
>It also introduces a few tenths of decibel loss (resistive) and that adds
>directly to the noise figure of the receiver!
>Overall you can expect about 0.8 to 1 dB degradation on receive and that
>also what most of them are specified.
>
>73,     Alex

73..de John/K4WJ
ex K8PXG 18 Jun 1959 to 11 Feb 1997
K8WJ 12 Feb 1997 to 08 Apr 1997