Are you certain that overdriving the front end of the KX3 that hard
isn't affecting the input impedance? It's an active front end.
73,
Dave AB7E
On 5/25/2022 10:54 AM, Ingo Meyer DK3RED wrote:
Hello Wunder,
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.
You ask for the receiver impedance, not the tramsmitter impedance. I
didn't know the answer. But I always assumed that it wasn't 50 ohms.
Therefore, I measured the impedance.
Meter: Vector Antenna Analyzer FA-VA5
<https://www.box73.de/product_info.php?products_id=4019>
Output Power: 5.6 dBm (S9+78.6 dB)
Impedanz: 50 ohms
Frequency: 7030 kHz
Object under test: Elecraft KX3
Conditions: ATU BYP, FREQ 7030 kHz, PRE OFF, ATT OFF
Measured data: Z = 76.0 ohms + j 9.0 ohms
Magnitude Z = 76,5 ohms, L = 204 nH
SWR = 1.56
73/72 de Ingo, DK3RED - Don't forget: the fun is the power!
www.qrp4fun.de - dk3...@qrp4fun.de
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