[hpsdr] Standalone Munin Testing

[Helmut, DC6NY]

Hi Lee,

I’m not familiar with the MFJ-269, but all these (scalar) analyzers are
using a bridge-circuit and display the measured impedance at a given
frequency. Usually we are using the 50 ohms system and the value of the
impedance relating to 50 ohms defines reflection or SWR. Assume you measure
25 ohms, so the SWR is 50/25=2 equal a reflection factor of 0.33 or 10 dB.
That’s still a reasonable value for an amp.
Example: I guess the output transformer L4 on the Munin has a winding ratio
1:4 or an impedance ratio of 1:16. This means the primary port of the
transformer has to ‘see’ 50/16=3.12 ohms to get optimal match. If you
substitute the each final MOSFETs with a 1.56 ohm resistor between source
and drain, you can evaluate your match by measuring the impedance at the
output jack of the amp.
You have to do this on the different bands, but please don’t ever apply the
supply voltage, hi.
BTW Hermes in the VNA mode together with a necessary test bridge is an
excellent tool for that kind of measuring.

73, Helmut, DC6NY

-----Ursprüngliche Nachricht-----
Von: Lee Mushel [mailto:herbert3 at centurytel.net] 
Gesendet: Mittwoch, 16. Oktober 2013 15:57
An: Helmut, DC6NY
Betreff: Re: [hpsdr] Standalone Munin Testing

Helmut,

Perhaps you could post a slightly more detailed discussion using the MFJ-269

for this.   I suspect you give folks credit for being somewhat smarter than 
they are! (Well, at least smarter than I am.)

73

Lee  K9WRU
----- Original Message ----- 
From: "Helmut, DC6NY" <dc6ny at gmx.de>
To: "'Tony Hagen'" <prosdr at gmail.com>; <hpsdr at lists.openhpsdr.org>
Sent: Wednesday, October 16, 2013 1:15 AM
Subject: Re: [hpsdr] Standalone Munin Testing


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