[TenTec] OT: Question to the group

Mon Jul 18 03:41:59 EDT 2016

>> Stating individual cases where something worked proves nothing.

Well, actually it does. As I pointed out, with a RESONANT cubical quad, driven with 470 Ohm Dentron parallel line, I got a perfect match on 20, 15 and 10. This was an efficient antenna with efficient feed lines and an efficient (in this application) tuner. It was positioned quite a long distance from the transmitter so the lower loss parallel feeling was of some advantage.

Better would have been the use low loss ceramic spacers and true parallel ladder line. However, the Johnson matchbox would have worked equally well in that application, whereas the autotuners and most of the T match tuners wouldn’t have worked at all without an external BALUN.

Since my radio at the time, a Drake TR7, had pretty good low pass filters within, I was not too concerned that the Matchbox offered no such lowpass filtering.

Even more important than the match is the near-perfect balance of currents on the line (as you mentioned). Two bad things happen when the currents on “parallel” lines are not balanced. Your noise level on receive goes up since the feedline begins to act as part of the antenna and your chances of getting the Worked All Neighbors award in transmit also goes up dramatically as the feed line begins to radiate where you do not want it to radiate.

Nothing matches everything. Nothing even works well for everything. Devices like this need to be matched to the application. I only sang the praises of the Johnson because it did indeed work with every application in which I used it.

Nothing else did as well…

As I said before, improvement is always welcome and what you discuss in terms of such improvements is great. Why does this become contentious?

A little humor, if that’s allowed:

I once got a perfect match with a Johnson Matchbox using two cats as an antenna, with alternately polarized mice as spacers for feed line made of old violin strings (catgut).

Of course, they were Siamese cats… It was, after all, a balanced dipole…

April fools...

Beyond that, what is wrong with resonant antennas? Where is the advantage of a non-resonant antenna? Nikola Tesla clearly showed the inherent advantages of resonant loads 120 years ago… They are pretty easy to match too!

> On Jul 18, 2016, at 1:09 AM, Gary J FollettDukes HiFi <dukeshifi at comcast.net> wrote:
> 
> I’ll just stay with resonant antennas…
> 
> Gary
> 
> 
>> On Jul 18, 2016, at 12:48 AM, rick at dj0ip.de <Rick at 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 at contesting.com] On Behalf Of Carter
>> Sent: Saturday, July 16, 2016 9:32 PM
>> To: tentec at 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
>> 
>> ---
>> This email has been checked for viruses by Avast antivirus software.
>> https://www.avast.com/antivirus
>> 
>> _______________________________________________
>> TenTec mailing list
>> TenTec at contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
>> 
>> _______________________________________________
>> TenTec mailing list
>> TenTec at contesting.com
>> http://lists.contesting.com/mailman/listinfo/tentec
> 
> _______________________________________________
> TenTec mailing list
> TenTec at contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec