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   Home   Help Search  
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Author Topic: Need Antenna Tuner Help  (Read 4440 times)
W5DXP
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« Reply #15 on: September 13, 2017, 10:45:31 AM »

Is this the antenna?    https://www.amazon.com/ZS6BKW-G5RV-Optimized-Antenna-Flex-Weave/dp/B00L8JKLFG

Good grief! If that antenna is worth $150, my junkbox is worth $10k. Wink
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KH6AQ
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Posts: 7718




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« Reply #16 on: September 13, 2017, 11:18:15 AM »

The ladder lock, wire, and ladder line (the same ones used in the antenna) add up to $65 at The Wireman. http://thewireman.com/index.html

The W2AU LL-TRANSULATOR is $25 at American Radio Supply. The total cost of the parts is $90.

http://www.americanradiosupply.com/coaxial-cable-to-ladder-line-transition-converter/
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KH6AQ
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« Reply #17 on: September 13, 2017, 11:58:28 AM »

Plus lugs and shipping from two suppliers rather than one. This makes the $150 price seem fair to me.
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KC4ZGP
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Posts: 1637




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« Reply #18 on: September 14, 2017, 05:51:26 AM »

Kraus,

You need 60pf for 7 MHz in a simple tuner - let's say 80pF to allow for reactance compensation.  For the 25mm and 50mm tubes, that means a length of 1 metre and a parasitic inductance of around 500nH. For 80m, double that.....

Gets a bit impractical compared to conventional parallel plate capacitors

I did say like in the real, real old days. In early radio, everything was big. They didn't know better.

Tubing comes in various diameters. One could arrange their copper tubing capacitors like organ pipes.

That would be novel. Heck several tubes in parallel to increase capacitance. Now that would be a solderer's
paradise.

Kraus
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G3RZP
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Posts: 8130




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« Reply #19 on: September 15, 2017, 03:31:38 AM »

When you are down at VLF, as in the early days of radio, you need larger components, especially when running power.
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KC4ZGP
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Posts: 1637




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« Reply #20 on: September 15, 2017, 05:49:13 AM »


Herr G3RZP,

Ah yes! Large...high voltage...high power...Ooohhh!!!

I'm having either power supply issues or cheap Chinese FETs with my EB-104. Starting over again.
I want it for just 160 meters phone.

Maybe that's why I'm so reluctant to get one of them store-bought amplifiers. So much capability and
I only want it for one band way down there.

Kraus
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K1JWJ
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Posts: 20




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« Reply #21 on: September 20, 2017, 03:48:13 PM »

I bought a used MFJ-949E from a fellow ham here. Have not used it yet as I am waiting for a new mic to arrive.

Can anyone send me a link to the proper balun/choke being suggested for my antenna? And, some clarity on exactly where I am to place it?

Thanks,

Jeff
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WB6BYU
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Posts: 17072




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« Reply #22 on: September 20, 2017, 09:14:29 PM »

Quote from: FRJEFF

...And, some clarity on exactly where I am to place it?...




Your antenna has ladder line or twinlead that comes down from the antenna to a lump
of some sort where the coax connects to it.  That lump should be a current balun
for best results, but many antennas just splice the coax straight to the twinlead instead.

(Manufacturers often quote G5RV to justify this, since he originally said not to use a
balun, but that was because of the primitive state of baluns at that time.  Really they
are being cheap.)

Assuming that there is a coax connector at that point, you can stick a "feedline choke"
like the MFJ-915 in series with the coax
at that point.  Other manufacturers sell similar products.  If you don't have a coax
connector, you can cut off the end you have currently and add a balun designed for the
feedpoint of an antenna, such as the MFJ-918 (and many others:  make sure it is a
1 : 1 current balun.)  Or you can wind some coax around a ferrite toroid core and
make your own using some of the designs from G3TXQ's page.
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