[Elecraft] Receiver impedance?

[Walter Underwood]

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)

> On May 25, 2022, at 10:05 AM, Wayne Burdick <n6kr at elecraft.com> wrote:
> 
> All antenna-facing stages in our receivers are designed for a nominal 50 ohm input. All of the preamp stages incorporate feedback to ensure a predictable, constant input impedance.
> 
> 73,
> Wayne
> N6KR
> 
> 
>> On May 25, 2022, at 9:44 AM, John Oppenheimer <john at kn5l.net> wrote:
>> 
>> Hi Walter,
>> 
>> Elecraft receivers, I'm familar with (K2,K3,KX[23], use "Feedback
>> Amplifiers" for their Pre Amp. The Feedback Amplifiers are designed for
>> nominal 50 ohm input impedance. Fifty ohm input impedance is somewhat
>> import for operation of the receiver bandpass filter.
>> 
>> I'll assume detector input impedance, preAmp bypass, is also nominal 50
>> ohm impedance.
>> 
>> John KN5L
>> 
>> On 5/25/22 11:05 AM, Walter Underwood wrote:
>>> What is a typical input impedance for modern receivers, or specifically Elecraft receivers? 
>>> 
>>> I’m asking because antenna tuners are a frequent question on an SWL group I follow and I’m pretty sure that they are not needed for most situations. If the receiver input impedance is not 50 Ω, that is a big data point.
>>> 
>>> My belief is that receivers are generally medium or high impedance, depending on whether the first RF preamp is bipolar or FET, but either way, mostly voltage-oriented.
>>> 
>>> And, yes, I know that antenna tuners can be a LPF or HPF, depending on their configuration.
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Elecraft at mailman.qth.net
>> 
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to n6kr at elecraft.com
> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to wunder at wunderwood.org