[TowerTalk] who's "right" (a tuner question)

[Mark Robinson]

Interesting.. I should try and hook up my mfj in place of my rig and see 
what the match on my two tuner tuned wire antennas looks like.


Mark N1UK

.
----- Original Message ----- 
From: "jim feldman" <mtnredhed at gmail.com>
To: <towertalk at contesting.com>
Sent: Tuesday, 07 December, 2010 2:45 AM
Subject: Re: [TowerTalk] who's "right" (a tuner question)


> 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.
>
> jim
> w6jmf
>
> On Mon, Dec 6, 2010 at 5:09 PM, jim feldman <mtnredhed at gmail.com> 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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