G5RV and automatic antenna tuning rigs
Terry Sellick
that use automatic antenna tuners? Thinking about trying one with my Yaesu
FT-920.
Thanks
Terry
CAM
It should work on 40m, 20m, & 12m. Maybe even on 80m. Probably not
on the other bands.
--
cheers, Cecil
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cw sebesta
foot of RG8X feedline. About 5:1 on 17 and 4:1 on 15 & 10 which ICOM doesn't
guarantee to match. I use the MFJ971 for the other bands.
73's de CW/ K5YO
"CAM" <Cecil....@IEEE.org> wrote in message
news:3B23D02D...@IEEE.org...
George, W5YR
internal tuner that is likely to be (a) very reactive and/or (b) with a
resistive component much over 150 ohms or less than about 17 ohms.
The problem, of course, is the possibility of large voltages or currents at
the tuner input depending upon the feedline Zo, length, antenna Z, etc.
etc. Most automatic internal tuners are relatively delicate and easily
damaged.
Frankly, I always run my lines through the old MJF 989C before letting my
756PRO, 765 or Kachina get a shot at it. The internal tuners are great for
keeping things in the ballpark as you shoot up and down the band.
But, I would be very careful about subjecting them to the cruel outside
world without some assistance.
72/73, George W5YR - the Yellow Rose of Texas QRP-L 1373 NETXQRP 6
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
Amateur Radio W5YR, in the 55th year and it just keeps getting better!
Icom IC-756PRO #02121 Kachina #91900556 IC-765 #02437
CAM
> My IC756 also works fine on 17,15, and 10. Probably due to using over 130
> foot of RG8X feedline. About 5:1 on 17 and 4:1 on 15 & 10 which ICOM doesn't
> guarantee to match. I use the MFJ971 for the other bands.
Yep, with enough coax you can get the SWR below 3:1 on all bands. :-)
I assumed the question involved internal autotuners. Something like
the SGC-230 will match a G5RV on all bands but it will be very
inefficient on some bands.
Mark Keith
> Just an old man's precaution about connecting *anything* to a modern rig
> internal tuner that is likely to be (a) very reactive and/or (b) with a
> resistive component much over 150 ohms or less than about 17 ohms.
>
> The problem, of course, is the possibility of large voltages or currents at
> the tuner input depending upon the feedline Zo, length, antenna Z, etc.
> etc. Most automatic internal tuners are relatively delicate and easily
> damaged.
>
> Frankly, I always run my lines through the old MJF 989C before letting my
> 756PRO, 765 or Kachina get a shot at it. The internal tuners are great for
> keeping things in the ballpark as you shoot up and down the band.
>
> But, I would be very careful about subjecting them to the cruel outside
> world without some assistance.
I agree. I'd pick up an outboard tuner for that. The cost of fixing the
internal tuner is too high to risk frying using in this manner. It's not
made to be a real wide range tuner, and won't handle excess heat .MK
Mike Williams
Interesting..
I am in the process of working out what to buy as a first rig.
I had just about settled on a TS-870 when someone told me about the internal
ATU 'problem' of such rigs.. I have a MJF-948 and errected a G5RV in
anticipation of great things!!
Indeed it seems that I might as well avoid such refinements and go for, say
a Yaesu 847, get the increased coverage and buy a VHF ATU. (OK so I will
probably need another antenna for 6 & 2m).
Any opinions please.
Many Thanks.
Mike
----------------------------------------------------------
M5WJF
"Mike Williams" <mik...@btinternet.com> wrote in message
news:B74EC05C.CFCC%mik...@btinternet.com...
The big problem I can see here is the balance between the rig you wish to
use and the antenna you wish to play with, Ł2,000 on a transceiver and Ł20
on a G5RV doesn't make any sense.
Money spent on the antenna will give much better performance.
Wayne M5WJF
K4IA
Radio K4IA
Buck
Fredericksburg, Virginia USA
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Meade
I just purchased an Icom IC-746 a few weeks ago, and put up my
first-ever G5RV to go with it. While I can't say the signal's the best
on all bands, the rig's internal tuner will tune it everywhere from 80
to 6 meters. I know it works extremely well on 20 (duh, the G5RV was
designed as a 20 meter antenna) -- I singlehandedly worked more than
400 contacts in 5 hours during Field Day with this setup. I've also
made quite a few contacts on 17 and 40 using the G5RV. I am very
pleased.
(BTW, I was in a hurry -- I usually build my own antennas, but this
one's a Van Gorden G5RV.)
Meade KA4RQB
Les
Gordon "All-Bander" 67 foot legs with 450 ohm ladder, no balun.
I have a K TS-440 with auto tunner.
What for balun should I put on this ? He said he was told I didn't
need a balun, just attach it to coax and into the tunner. I dodn't
recall hereing this before.
I have a 20 year old setup I put up when first licensed around 1979 or
so. It is a W1AW ?? balun fed with 50ohm coax. It still seems to
work, but I figure after 20+ years of being up I should think about
replacing it.
Thanks, Les
KA3ADU
Mark Keith
> Hi, I have a question along the same lines. A buddy gave me a new Van
> Gordon "All-Bander" 67 foot legs with 450 ohm ladder, no balun.
> I have a K TS-440 with auto tunner.
> What for balun should I put on this ? He said he was told I didn't
> need a balun, just attach it to coax and into the tunner. I dodn't
> recall hereing this before.
>
> I have a 20 year old setup I put up when first licensed around 1979 or
> so. It is a W1AW ?? balun fed with 50ohm coax. It still seems to
> work, but I figure after 20+ years of being up I should think about
> replacing it.
>
> Thanks, Les
>
> KA3ADU
I would not do it, unless you want to burn up that internal tuner.
Same with the guy running the 746. Just because you can get a match
doesn't mean the tuner is made to handle the excess heat that can be
generated trying to match a load that is way off from 50 ohms. These
tuners are not made for this purpose. They are installed to use as a
line "flattener" to assure a good match for the solid state finals.
They really are not made to handle much more than a 3:1 to 5:1
mismatch. Will vary on the tuner. I would only use an outboard tuner
when running a ladder line setup such as that. It's not worth frying
the internal tuner which will probably cost more to replace than
buying a tuner made for the purpose. An internal tuner won't like
20-40-60+ to 1 mismatches. These ratio's can be common on certain
bands. IE: Running 20m on a 65 ft 40m dipole. MK
CAM
> I would not do it, unless you want to burn up that internal tuner.
> Same with the guy running the 746. Just because you can get a match
> doesn't mean the tuner is made to handle the excess heat that can be
> generated trying to match a load that is way off from 50 ohms. These
> tuners are not made for this purpose. They are installed to use as a
> line "flattener" to assure a good match for the solid state finals.
> They really are not made to handle much more than a 3:1 to 5:1
> mismatch. Will vary on the tuner. I would only use an outboard tuner
> when running a ladder line setup such as that. It's not worth frying
> the internal tuner which will probably cost more to replace than
> buying a tuner made for the purpose. An internal tuner won't like
> 20-40-60+ to 1 mismatches. These ratio's can be common on certain
> bands. IE: Running 20m on a 65 ft 40m dipole. MK
Another solution for transceivers with internal tuners is to vary the
length of the ladder-line per band. The antenna can be tuned to mid-band
by varying the length of the ladder-line and then tuned across the band
with the internal tuner. The idea is presented at:
http://people.delphi.com/cecilmoore/mystery.htm