[TowerTalk] TH6-DXX Band segment settings

Fri Nov 8 05:07:06 EST 2024

I also agree with what Karl said but I believe the average improvement over a dipole for this antenna on 20 and 15 is likely to be less than 4 dB.  A full sized, computer optimized 3 element monoband Yagi will have about 5-1/4 dB over a dipole. Their manual says forward gain is 9.5 dB (should be dBi) That could be true for peak gain at some frequency on 10m but absolutely is not true for 20 and 15.

The TH6DXX  was designed fifty years ago and was an unbelievably good design at that time.

You have aluminum tubing which is as good or better than what you could buy today. You may not want to do this but a good project would be either find some more tubing or buy some new tubing to go with what you have and use the 24 foot boom to build a 12 element antenna with 3 on 20, 4 on 15 and 5 on 10m ( full sized elements). I’m sure if your traps are good someone out there would like to buy them. You would also have the option of making a Yagi with full sized elements that would include 17 and 12 meters.

The result will be a lot more gain (1-2 dB is huge), better F/R and a low SWR across the entire 20 and 15m bands and about 800 khz of 10m. You would never use an antenna tuner.  It would survive more than 80 mph which Hygain  claimed and more ice load. The antenna will probably weigh less and you will not have the worries associated with all those traps.  It would be nice to know you have the very best you could do with whatever boom length and most likely never have to take it down for repair.

Stan, ZF9CW

> On Nov 8, 2024, at 12:40 AM, maflukey at gmail.com wrote:
> 
> Just reiterating Rick's comment about Hygain baluns...   I think there may
> have been a couple of different models, but I've acquired nine used Hygain
> monobanders over the years and the baluns that came with all of them were
> not worth reinstalling.   So, I second Rick's advice to get decent balun for
> your antenna.   Also, some folks have said that getting the driven element
> adjusted properly on a TH-6 is a bit of a PITA.    If you have any way to do
> that and mark it ahead of time it might save you some frustration up on the
> tower later.
> 
> 73 & good luck on your project.
> 
> Matt
> KM5VI
> 
> 
> 
> -----Original Message-----
> From: TowerTalk <towertalk-bounces at contesting.com> On Behalf Of Richard
> Karlquist
> Sent: Thursday, November 7, 2024 2:53 PM
> To: Gerry Maira <sparks234 at twc.com>
> Cc: 'towertalk at contesting.com' <towertalk at contesting.com>
> Subject: Re: [TowerTalk] TH6-DXX Band segment settings
> 
> I see you dug up one of my old posts.  The only thing I would add to that
> post is that is that anecdotal reports of using a tuner to extend the
> bandwidth of such Yagi's may say "it seemed to work fine" only indicate that
> no effective tests were done to measure it.  Consider
> this:  the TH6DXX has 6 or maybe 7 dB gain over a dipole at best.  Using a
> tuner, the gain will never be less than a dipole.  So it will work as well
> as a dipole.  For casual operation, that may work just fine.  It's only down
> 1 S unit.
> 
> Regarding baluns:  The TH6 was designed when hams were limited to 1kW DC
> input equivalent to 600W RF out on a good day.  Using 1,500 W out may blow
> the balun up, especially if you have high VSWR.  Recommend you make a
> homebrew balun as per K9YC's cookbook.
> 
> ---
> Rick Karlquist
> N6RK
> 
>> On 2024-11-07 10:35, Gerry Maira wrote:
>> 
>> I recently bought a TH6-DXX in excellent condition and I'm getting
>> ready to put it up at 70'. With the space limitations I have, this
>> antenna is well suited for me since it can be put up 1/2 at a time - 2
>> 12-foot boom sections instead of the complete 24' boom. Once it's up,
>> it would be very difficult to make any changes. I plan to use a
>> Hy-Gain BN-4000B choke but also have a Radio Works Y1-5K or could make
>> one from RG-213.
>> 
>> I operate CW mostly and that is where performance is most important to
>> me. Phone coverage is important too, though not as much. Looking at
>> the SWR plots in the manual for the band segment choices (CW, Lo Phone
>> and Hi phone) it seems that CW would be the obvious choice for me.
>> Those curves are steep though, and I wonder if with CW, I would still
>> have full coverage of 15 and 20 meters, using a tuner and possibly
>> reduced power for the high ends of those bands. Same goes for 10
>> meters, say up to 29.2 MHz but a lower freq. could be acceptable
>> there.
>> 
>> The other choice would be the Lo Phone setting, and using a tuner /
>> possibly reduced power at the low and high ends of the bands,
>> including where I spend most of my time on CW.
>> 
>> I couldn't find much info on this topic when searching the TT archives
>> but did find the old post below, and I'm a little concerned to say the
>> least! Was the antenna actually designed to be used only in one
>> segment of each band, even with a tuner? Will I be Ok with the CW
>> setting or would that give me serious problems on phone? If I used the
>> Lo Phone setting, would I have problems in the CW portions of the
>> bands running 750W and a tuner?
>> 
>> I used a TH6 frequently many years ago at a club station, but I don't
>> know how that one was set. It seemed to work fine on any freq but I
>> probably never tried it above 29 MHz on 10 meters. I would have been
>> using a tuner when the SWR was high, but there never seemed to be any
>> loss in performance - which was always very good. Never had to reduce
>> power from 800W either. The choke there was just several turns of
>> RG-213 as described in the manual.
>> 
>> Any advice is appreciated.
>> 
>> Thanks,
>> Gerry KA2MGE
>> 
>> ----------------------------------------------------------------------
>> ----------------------------------------------------------------------
>> ---------------
>> 
>> You can see the bad news: choose from CW, low phone, or high phone.
>> Hope you don't need more than one of those segments :-( Also, you
>> can't "cheat" the SWR curves by using a tuner. The pattern will
>> significantly degrade at the frequencies where the SWR is high. This
>> is why, IMHO, given a choice between a TH6 and TH7, picking the TH7 is
>> a no brainer. I used to have a TH6. I would never go back to that.
>> Rick N6RK aschnabolk wrote: >_ Look at Page 2 of 7 in the "TH6DXX"
>> (last one listed) Curves are there. As_ >_ I_ >_ remember mine when it
>> was up, curves were similar._ >_ 73_ >_ Al W2OIB_
>> _______________________________________________
>> 
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