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Author Topic: QRP antenna tuner  (Read 7224 times)
KM1H
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Posts: 2633




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« Reply #15 on: August 05, 2017, 08:08:58 AM »

Use something rated for at least 100W in order to minimize losses and use a fairly Hi C circuit as coil losses can really ruin your day.

Carl
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AE0Q
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Posts: 66


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« Reply #16 on: August 07, 2017, 08:10:45 AM »

Use something rated for at least 100W in order to minimize losses and use a fairly Hi C circuit as coil losses can really ruin your day.
Carl

Good advice from Carl, use a tuner rated for the next level of power higher than what you're running. Tiny, small inductors may be inefficient.

Something else is the choice of circuit design. The L-match (most autotuners) is easier to adjust for an efficient match (usually only one setting of C and L gives a match), the T-match can show a good match over many combinations of the C and L settings and some are putting all the power into the inductor and not antenna.

Glenn AE0Q
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Glenn and V-NATCH Katie,
HP-O, MXB, MJB, XF
http://www.hoopsandjumps.com/
http://funagility.webs.com/
KM1H
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Posts: 2633




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« Reply #17 on: August 08, 2017, 03:38:49 PM »

Quote
Something else is the choice of circuit design. The L-match (most autotuners) is easier to adjust for an efficient match (usually only one setting of C and L gives a match), the T-match can show a good match over many combinations of the C and L settings and some are putting all the power into the inductor and not antenna.

The T Match can also use the coil as a dummy load especially when it is a rotary inductor. Ive seen the results of 1500W into MFJ junk in particular.

The L Match can also be switched for loads above and below the nominal 50-75 Ohms desired.

Carl
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AK0B
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Posts: 269




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« Reply #18 on: August 19, 2017, 08:20:52 PM »

I have several tuners some purchased and several I built.

The ZM-2 is an excellent design and buy.  It will teach you a lot about how to turn various types of antenna.

I also have auto - LDG and a couple built in to the transmitter. What I don't like -- all auto type have a swr they are happy with and it might not be 1:1.  And they like to go back to an old value it stored away when you want it to retune.

A pi type has to have a lot of capacitance on the input side to match a 5 watt qrp transmitter  best to just switch the input and output lines and it will do a better job.

Several big boy versions of the ZM-2 on the web.  Some of the best built by the fellows from VK land.

73, Stan AK0B   
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KA0USE
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Posts: 20




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« Reply #19 on: November 15, 2017, 06:26:40 PM »

I have several LDG tuners.  LDG builds a quality unit, made in the US, fully documented and the company offers fantastic customer service.

Other than that, not much to recommend them... Grin

you made me snort! hmpf, hope you're happy...
i, too have an ldg tuner for the '817. works as advertised.
other than that, not much to recommend them, hahahahahahaha!
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