Roger, then let's stay with resonant antennas.
The feedpoint impedance is not only dependant on the impedance of the antenna
but also on the transformation of impedance due to the specific length of
feedline . . . which varies from one band to another.
At field Day, K5EOK in OKC in 2009, we had an 80m resonant dipole up 50 ft. and
100 ft. of brand new 450 Ohm Wireman Window line. This was our all band
antenna for our GOTO station.
We terminated it into the 275w Johnson Viking Matchbox and had two bands which
would not match.
I substituted my MFJ-974 and we were able to match all bands.
The temperature outside was over 100 degrees (F).
We had to choose between leaving the air conditioned shack and go back out and
play with feedline lengths in order to use the JVM, or simply use the MFJ.
We used the MFJ.
It was a unanimous decision.
For home use, I too would use the JVM because of its higher efficiency and
better balance, but there I have time to play with feedline lengths and find
one that works. Often they work without adjustment, but not always.
I'm not saying the JVM is bad. It's not. It's great.
But it definitely will not match everything because it is limited in matching
range compared to many other matchboxes.
73
Rick, DJ0IP
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Gary J
FollettDukes HiFi
Sent: Monday, July 18, 2016 8:10 AM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] OT: Question to the group
I’ll just stay with resonant antennas…
Gary
> On Jul 18, 2016, at 12:48 AM, rick@dj0ip.de <Rick@dj0ip.de> wrote:
>
> Stating individual cases where something worked proves nothing.
> I've had half a dozen cases where it did not work and other matchboxes did.
>
> In order to gain clarity on this, you must try it with all kinds of
> antennas; resonant antennas, long antennas, short antennas, odd sized
> loops, etc.
>
> What the Johnson does well is push equal amounts of current into both
> wires of the feedline with relatively high efficience, if and only if
> it finds a match.
> What it does poor is match over a very broad matching range.
>
> You don't have to trust me; try it as I have and compare it to an
> MFJ-974 or MHF-976.
>
> OR... simply read the ARRL test report where the ARRL shows several
> balanced matchboxes and their matching ranges, including the JVM.
>
> Now I guess I have to go research the issue it was printed in because
> it's probably too much work for some of the readers.
>> "A New Generation of Balanced Antenna Tuners", by Joel Hallas, W1ZR,
>> QST
> September 2004.
>
> OR, simply do what I have said her MANY TIMES, go to my web site, find
> the page on MATCHBOX-SHOOTOUT And read the page, plus download the
> file at the bottom of the page.
> THERE you will find a nice colorful Excel spreadsheet comparing the
> matching range of the various matchboxes.
> THERE you will see that the JVM was indeed limited in matching range.
>
> THEN go read my web page on how to fix it.
>
> AND THEN YOU WILL HAVE THE BEST MATCHBOX EVER! ;-)
>
> 73
> Rick, DJ0IP
>
>
> -----Original Message-----
> From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of
> Carter
> Sent: Saturday, July 16, 2016 9:32 PM
> To: tentec@contesting.com
> Subject: Re: [TenTec] OT: Question to the group
>
> On 7/16/2016 10:13 AM, Carter wrote:
>> On 7/15/2016 6:59 PM, Jim Allen wrote:
>>
>>> I had one of those [135 foot dipole fed with ladder line], not at >
>>> 60', about half that. CC&Rs and all that.
>>
>> The exact setup I've got, also at 30 feet.
>>
>>> What is a "well designed truly balanced antenna tuner?" From what
>>> > I've read, there aren't many.
>>
>> Johnson Matchbox, kW or 275 watt version, not "perfection" but
>> certainly very good -- and readily available at a fairly modest price.
>>
>> Just my 2 cents...
>>
>> Carter K8VT
>>
>
> Sorry, forgot to mention it earlier...
>
> Not to say my Johnson kW matchbox is the "best ever"; however, it
> works flawlessly with my FT1000MP and 135 foot ladder line fed dipole
> on ALL (including WARC) bands. Worst case is 2.1:1 on 30 meters, all
> other bands 1:1.
>
> Carter K8VT
>
> ---
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