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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