[TenTec] Jupiter Autotuner upgrade?

Wed Nov 30 08:48:14 PST 2011

John, sorry we got so far off track on your thread; we're back!

Oops, I assumed you had an MFJ "Auto-Tuner".

None of the auto tuners, regardless of brand, will have as wide of a
matching range as most of the manual tuners.
MFJ does not publish the specs for matching range of that tuner but it's
going to be several thousand Ohms.

Heed Geoff's warning, as the impedance (SWR) gets higher, the maximum amount
of power you can run through it will degrade.
BTW, most, maybe ALL manufactures print that same warning in their manual,
even including the ones like Palstar.  It's true for all matchboxes,
regardless of make.

And for Geoff, let me bring you up to date.  MFJ finally came out and
admitted they were publishing their specs like they were rated in the old
days, meaning "Input Power on SSB".  So yes, a 300w rating is going to be
good for about 100w!  I can't remember where I read it but I believe it was
in the manual of one of their tuners I bought.  Of course you have to read
every page in the book before you find this message.  They certainly didn't
broadcast it!

John, to your specific needs, even though the 949E has a broader matching
range, if your goal is to match your G5RV, you will be OK with any of the
Automatic Tuners, built-in or external.

When you talk about working DX and being fussy close in, you did not specify
a band.
I assume you are talking about the high bands, not the low bands.
That is a result of propagation, not choice of antennas.  Changing antennas
or matchboxes won't help.
If you are experiencing this on 40 or 80m, then there's something rotten in
Denmark!

I'm not an expert on the G5RV, and it has been lightyears since I've read up
on it.  I'm sure the Internet would provide the specifics.  As I recall
(grain of salt), on 80 and 40 it still behaves pretty much like a dipole,
meaning it should favor directions off the side, but . . . ONLY IF high
enough in the air - which means about 66' for 40m and 132' for 80m.
You can probably reduce that to 50' and 100' and still find it to be true,
but when you have it lower than that, which you do, it tends to become more
omni-directional.  I said "a bit more", not that it is fully
omin-directional.  IF SOMEONE WANTS TO JUMP IN AND CORRECT ME HERE, I WON'T
BE OFFENDED.

73
Rick, DJ0IP

-----Original Message-----
From: tentec-bounces at contesting.com [mailto:tentec-bounces at contesting.com]
On Behalf Of John
Sent: Wednesday, November 30, 2011 4:32 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Jupiter Autotuner upgrade?

The tuner is a MFJ- 949e rated at 300 watts.  I have not been able to 
find the specs other than it is  built to handle 300 W and will resonate 
most antennas.  It has tuned antennas for me for a long time without a 
protest.  Where do you find the specifications for the tuners?  I keep 
looking but only find the most general of specs, 300 watts etc.

My antenna is a G5RV with a 3/4 in twin lead feeder to normal coax.  I 
forgot who made it as I have had it up for a long time.  It is full 
size, not one of the ?double or half size antennas I see offered from 
time to time.  In the FWIW department the peak is about 40-45 ft with 
the ends about 25-30 ft on one end and probably 40 ft on the other.  It 
goes out over a slope on that side.  It works well for DX (that means  I 
can make contacts) but is very fussy close in (within 10 mi.) and seems 
very directive.   I have trouble working a few people who are close in, 
although they may have minor things like rock between us.  I am on Cape 
Ann err Manchester, MA (Gloucesterites get a bit fussy about who claims 
to reside on Cape Ann)  and there is a reason that one community is 
named Rockport.  I have never seen a pattern for the G5RV on bands other 
than 20 M and guess it is acting pretty much as an untuned dipole on 
bands other than 20 M.  Is this a bad assumption?

Thanks for the information.

73,
John / WA1JG

On 11/30/2011 3:33 AM, Rick - DJ0IP / NJ0IP wrote:
> John,
>
> The G5RV (if it is really built like the G5RV suggested antenna) has an
> impedance "close" to 50 Ohms on 80 and 40 and most other HF bands.  The
> Jupiter's built-in tuner will have no problem matching it.
>
> If you have a "G5RV-like" antenna, such as it has the length of the G5RV,
> but runs openwire all the way to the shack, then the answer is "maybe".
>
> You asked to compare it to your MFJ tuner but that is like saying you have
a
> car and asking if the gas mileage of a new Corvette will be as good as the
> one you have - hi.  We can't answer until we know what car you have.
>
> If you dig into the specs of the MFJ tuners you will find that most
specify
> that they can match up to about 1600 Ohms.
> Two or three say they can match up to 3200 Ohms.
> Some can match to 1200 Ohms, while there are one or two others that only
> match to about 800 Ohms.  BTW, it's the high power tuners which have the
> lower matching ranges.
>
> I will make a HUGE assumption here and say that the Jupiter's tuner will
> probably match about the same as the MFJ that can match up to 1200 Ohms.
It
> certainly is not going to match the range that the 3200 Ohms tuners can
> match.  Maybe someone who owns one can check the manual and see if the
specs
> on the matching range are printed.
>
> 73
> Rick, DJ0IP
>
>
> On 11/29/2011 12:26 PM, John wrote:
>> I am considering adding the autotuner to my Jupiter.  My normal antenna
>> for now is a G5RV with plans for getting my R-7 Vertical back on the air
>> ASAP.  Other than making me feel better, what is gained by adding the
>> autotuner to the mix.  The G5RV gets quirky to tune on 80 and 40 using
>> my MFJ tuner. Will a G5RV be within the tuning range of the TT autotuner
>> with these bands and antenna?  Any experiences are appreciated.
>>
>> 73,
>>
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