About 40 years ago I was a Responsible Engineer for the Phoenix Missile
Receiver/Transmitter Unit (RTU). This was a monopulse radar and my unit fed ~30
MHz i-f signals to the following Electronics Unit (EU) which did the signal
processing. The EU test position had a Collins 51S-1 receiver in it just to
measure the output levels of the RTU. As usual there was always finger pointing
when specs weren't met. As a referee a PhD was brought in to analyze the
interface of the two units. At one point he focused on the input match of the
51S-1 and since I was the RF guy, I was asked to measure it. The numbers are
fuzzy but suffice it to say, he wasn't happy and asked me to fix it. I gathered
up some General Radio airline stuff and built a double-stubbed tuner and got it
to about 40 dB return loss.
He came back about an hour later with two pages of equations, written in
mouse-type that almost required a magnifier to read, and happily announced that
his "quick analysis" showed that the error would be some (unmemorable) fraction
of a dB. Everyone was happy.
I never had the heart to tell him that the minute the AGC activated, all bets
were off.
So the answer to the question is, it depends.
Wes N7WS
On 5/25/2022 11:18 AM, Walter Underwood wrote:
Thanks. I’ll make a wild generalization that transceivers are generally
designed for the receiver portion to be 50 Ω.
Anybody have an idea about SWL receivers?
wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)
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