ok, a little more testing. I set up on 7.230. I tuned via the noise peak
and then used low power to dial in. Both the TS-940 and the meter on the
antenna tuner agreed the match was at or near 1:1. Next, I
then disconnected the feed from the transceiver and substituted the mfj-259.
I dialed the vfo on it to 7.23 (or as close as I could get it to stay) and
the swr needle on the analyzer was by the infinity mark. I then plugged the
antenna feed line directly into the mfj and got a 2:1 b/w of 7.23 to 7.33
that dipped to 1.7:1 in the middle.
observed: MFJ-259 is ok connected directly to antenna, not ok when feeding
the T match. I would have to say that local RF sources are not the cause of
the difference. I also verified that the swr as measured by the
ts-940/tuner was the same at full power as it was at 7 or so watts. I'm
not sure why the tuner and the analyzer don't get along. I am settled on
the fact that the inline meters are likely correct.
The MFJ-259 may be ok for some uses, but driving this T match and antenna
isn't one of them.
On Mon, Dec 6, 2010 at 5:09 PM, jim feldman <firstname.lastname@example.org> wrote:
> It took me a little while to understand how a strong BCB station might do
> this, but I assume it's because the MFJ "sees" the signal as reflected
> power? I didn't (and don't) see that if I plug right into the antenna feed
> line. Someone suggested dialing it in via the tuner/transmitter swr meters
> and then checking the match via the MFJ289. I'll try that this evening and
> report back the results (little embarrassed I didn't think to try that).
> I'm not saying that isn't the case but I've been successfully using the
> analyzer for some months on vhf antenna projects with quite low matches, and
> I also periodically test the trapped vertical, and get back pretty good
> matches on 10 15 and 20. Even 40 is pretty good. 75 is just very narrow,
> but under 2:1
> Thanks for everyone's help
> jim w6jmf
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