[Elecraft] Receiver impedance?

[Edward Mccann]

Hope the Phoenix Missile hit its target!

Ed McCann
AG6CX

Sent from my iPhone

> On May 25, 2022, at 12:46 PM, Wes <wes_n7ws at triconet.org> wrote:
> 
> 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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