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Re: [TowerTalk] Xm 240

To: towertalk@contesting.com
Subject: Re: [TowerTalk] Xm 240
From: "Lux, Jim" <jim@luxfamily.com>
Date: Sun, 27 Nov 2022 09:12:32 -0800
List-post: <mailto:towertalk@contesting.com>
On 11/27/22 8:37 AM, Grant Saviers wrote:
The MFJ259 is pretty useless in an RF environment.  It has very poor selectivity to overload.  Found this tuning 40 and 80m verticals 4 miles from a BCB station.

Newer SWR meters are much more resistant, but still can be overloaded. The alternative is to try 5 to 10w transmit, whatever makes the radio swr or external meter read reliably and sweep the band.


Or get something like a NanoVNA, which has a narrow band receiver. Although, I suppose you could saturate the mixer if you have a strong enough signal. But you'll know it if that occurs, because the S11 magnitude will look pretty wonky (spikes where a harmonic of interference happens to mix with a harmonic of the LO).

The NanoVNA H4 (with the 4" screen) is $80 from R&L.


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