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Author Topic: Recommendations for portable tuner  (Read 379 times)
G1MZP
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Posts: 32




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« on: June 25, 2008, 10:45:51 AM »

I wonder if anybody has any ideas for a tuner for portable and static mobile operation.

I want to use alongside my 897, expermenting with random wires, dipoles, verticals etc.

Must not be too massive for the portable use, not really bothered either way if its auto or not

Thanks

Alan
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AD5X
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Posts: 1432




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« Reply #1 on: June 25, 2008, 11:13:47 AM »

I used an MFJ-902 for several years to go along with my portable station (IC-706MKIIG).  I modified that tuner to include a resistive SWR bridge and a LED SWR indiccator (info on my website at www.ad5x.com).  Last year I changed to a MFJ-925 auto-tuner.  A little bigger, but I've become spoiled by auto-tuners!!

Phil - AD5X
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G1MZP
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« Reply #2 on: June 25, 2008, 11:21:52 AM »

Imustadmit I have been looking at the 925, but nobody I have spoken to have any stock, quoting 14 weeks delivery....

I can't wait that long!


Alan
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W3JJH
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« Reply #3 on: June 25, 2008, 11:23:42 AM »

I've had good luck with my MFJ-971.
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G1MZP
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Posts: 32




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« Reply #4 on: June 25, 2008, 11:35:52 AM »

Thanks for the feedback on the 971, I have been offered a used one at a reasonable price

Regards
alan
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N4ABA
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Posts: 44




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« Reply #5 on: June 25, 2008, 11:43:24 AM »

I've got one of the cheap MFJ 16010 tuners which I use with my 857 and 817.  Works fine utilizing the SWR/S meter ("guess meter") in the rigs.  Light and economical.  Also have a Kenwood AT250 which works great.  Either will drive the OCF/twinlead antenna just fine and lets me work most bands.  Also use the PAR end-fed antennas for port. work with the 817.  No tuner with the PAR antennas.

Cheers;
Andrew
N4ABA
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WB6BYU
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Posts: 13331




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« Reply #6 on: June 25, 2008, 12:26:50 PM »

I like my old Ten-Tec AT-5(?)

It is just a coil and dual capacitor arranged as a parallel
tuned circuit with the center tap of the capacitor grounded.
There is a link coil of a few turns that couples to the
coax, two leads with croc clips to adjust where the
capacitor connects to the coil, and two more croc leads
to set the taps for the output terminals.  I've used it
on all sorts of single wires and balanced lines.  It doesn't
work as well with very low impedance loads, though, and
the coil taps are too far apart for convenient use on
15 and 10m.  But you could build your own with more
convenient taps and an option to open the center of the
coil for series tuning.

There are many tuner designs, depending on the range of
impedances you want to match.  If you are going to match
coax with a high SWR then the standard T tuner is a good
choice as it can match low impedances with reasonable
sized capacitors.  (An SWR of 10 : 1 on 50 ohm coax means
the impedance at the tuner could be as low as 5 ohms.)
End-fed wires have a limited range of impedances to
match: you won't find a 5 ohm load without a lot of
capacitance, so you can design the tuner accordingly.
There is an excellent design by Ulrich Rhode DJ2LR in
QST (December 1984 I think?) that used a standard L
network following a 4 : 1 stepdown transformer, so it
always matched from 12.5 ohms up to the load.  With the
addition of a fixed capacitor and coil to the normal
variable ones this gave a very wide range unit including
160m.

Here are some other tuner designs you can try:
http://www.xs4all.nl/~pa0fri/ATU/Anttuners.htm#E

Just about any of the commercial T-network tuners will
work for what you want with reasonable efficiency. (Or
you can build your own.)  That is a good choice for
a single tuner with a wide tuning range, which is often
the case with antenna experimentation.  Once you find an
antenna that you like you can build a preset custom
tuner for it and free up the variable one for other
experiments.
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G1MZP
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Posts: 32




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« Reply #7 on: June 25, 2008, 01:30:24 PM »

Thanks for the detailed response.

Its early days for my construction project, so I am going to wimp out and buy the tuner, but build the antenna

small steps....


Alan
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PD2R
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Posts: 131




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« Reply #8 on: June 25, 2008, 03:00:12 PM »

How about one of these beautiful tuners: http://www.lltuners.nl/

But you mentioned earlier that you can't wait very long so it probably isn't an option.
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VA7CPC
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Posts: 2391




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« Reply #9 on: June 26, 2008, 12:19:27 AM »

I've used an LDG Z-11 Pro autotuner for portable operation.  It's about the same size as an FT-817, but much lighter, and it's popular among FT-817 owners.

Since I do "picnic table portable" work, I can afford the size and weight.  The battery pack is 8 AA batteries, which last nearly forever.    

I've only used it _portable_ at QRP levels.  But it worked fine in my apartment, driving a balcony-mounted vertical at 100 watts, _way_ off resonance.  And I think it's rated for 125 watts.

       Charles
   
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G8JNJ
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Posts: 493


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« Reply #10 on: June 26, 2008, 03:56:04 AM »

Hi,

I'd second the Z-11pro fitted with internal batteries.

The power consupmtion is low and the use of latching relays mean that batteries last a very long time.

It's a very useful bit of kit to have around for all sorts of antenna expriements.

You can either use it at the tranceiver to 'mop up' poor matches, or at the base of an antenna as an auto-tuner.

The impedance matching range is as good or better than many other models, and the insertion loss is low, even when feeding difficult loads.

Martin - G8JNJ

www.g8jnj.webs.com
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