Eric:

LMR400 will be my coax of choice the next time I re-do my installation,
especially for 2-meters and 440.  Obviously, this won't be as critical for
HF, so I may be able to cut costs down a bit with a cheaper coax variety for
those frequencies.

Regarding your antenna analyzer suggestion, checking the readings at the
radio end will be easy, but getting someone to climb up onto my steep roof
to do the readings at the antenna feed point may be a bit more challenging.
But, I may try to go in that direction anyway.  In the meantime, I guess I
can settle for just using low power for our local 440 repeater, which is
very close to my house anyway.

Tom Behler: KB8TYJ




-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Eric Oyen
Sent: Saturday, May 17, 2014 2:16 PM
To: [log in to unmask]
Subject: Re: Question on interpreting TW2 Readings with TMV71A At Home QTH

that sounds almost typical of older 9913 coax. You will get better = results
with LMR-400. There may also be an issue with your antenna feed = point
(loose connector, cold solder joint, etc.). That or the antenna, = itself,
needs to be retuned. If you have someone there that has an = Antenna
Analyzer, have them stop by and do a couple of measurements (one = at the
radio and the other at the antenna). That will usually narrow = down the
problem.

-eric

On May 17, 2014, at 10:42 AM, Tom Behler wrote:

> Hi, all.
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> Well, I was out at the RV camp site briefly yesterday afternoon, and  
>re-tested my TMV71A out there with the dual-band mobile antenna that =
is now
> attached to the RV, and using my TW2 to take the needed readings.
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> Now that I've learned how to do the TW2 band switching properly, I'm =
happy
> to report that the readings out there look good, and make perfect =
sense.
> SWR's on both 2 meters and 440 are no higher than 1.2 to 1, and the =
output
> power readings on both bands are in line with what I'd expect for the  
>TMV71A.
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> However, I still think I might have an issue with my Diamond X200A =
antenna
> that is mounted on the roof here at the home QTH, especially on 440.  
> =
The
> antenna is near the peak of the roof, up about 40 feet or so, and is =
fed by
> RG9913 coax.
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> Here are some readings I get with the TMV71A, and my TW2:
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> 2-meters on 146.47 MHZ simplex:
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> SWR =3D 1.2 to 1;  Forward Power =3D 41 watts;  Reflected Power =3D =
0.6 watts.
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> Not too bad in my opinion.
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> 440 on our local repeater frequency of 443.900:
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> SWR =3D 2.4 to 1;  Forward Power =3D 30 watts;  Reflected Power =3D 5 
>=
watts.
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> I'd be interested in anyone's thoughts as to what these readings are =
telling
> me.  Although not terrible, my SWR and power readings on 440 are not =
what
> I'd like them to be, and I suspect that the lower forward power =
readings are
> due at least somewhat to the fact that the TMV71A may be folding back 
> =
a bit
> due to the 2.4 to 1 SWR.  I'm not exactly sure how to re-tune the =
Diamond
> X200A for 440 to allow it to perform better, and certainly don't want 
> =
to get
> someone to climb up on the roof with an antenna analyzer to help until 
> =
I
> have a very good idea as to what adjustments need to be made.
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> In the meantime, I guess I'm fortunate in that the only 440 repeater =
in our
> local area is about a mile from my house, and can be hit easily with 5  
>watts.
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> Part of me just says:  "If it ain't broken, don't try to fix it.";  =
but the
> slightly elevated SWR on 440 does concern me a bit.
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> Tom Behler: KB8TYJ
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