[Antennas] From transmission lines to tuners

2002年12月23日 10:20:59 -0800

Hello Randy
I highly recommend two books, Transmission Line Transformers, by Jerry
Sevick, W2FMI,
and Building and Using Baluns and Ununs, also by Sevick.
You can find information on almost any transformation ratio you need in
these books.
The second one has more constructional material, while the first covers both
how they work and how to make them.
I have been making all my own baluns and ununs for some time now. With
these books, it's
very easy.
73, Bob N6WG
-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of [email protected]
Sent: Monday, December 23, 2002 9:15 AM
To: 'N7WS'
Cc: [email protected]
Subject: RE: [Antennas] From transmission lines to tuners
Good morning Guys,
I'd like the instructions for the home made balun.
I would like to make a 4:1 and a 9:1
This is a task I want to learn to do. I know I can buy stuff at the
store or swap meets. The point is I want to learn how to make them
myself
Randy
AC7NJ
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of N7WS
Sent: Monday, December 23, 2002 16:45
To: [email protected]; [email protected]
Subject: Re: [Antennas] From transmission lines to tuners
At 08:50 12/21/02 -0800, Steve L. wrote:
>>> A KW into a tuner with 60% loss means that the tuner
>> must dissipate
>> 600 watts - not likely.
>>This has been my 'bull$hit' touchstone for many years.
>>>My Alpha 99 with the optional cooling fan can TX a
>continuous 1500W output forever. I've sent 5-6 minute
>continuous RTTY transmissions at that power level many
>times over a few hours... and I can't feel any rise of
>temp in the transmatch except the ferrite balun. I can
>easily leave my hand firmly gripped onto the balun and
>wires after that transmission.... meaning we are
>dealing with what, 25W? Out of 1500?
>>I do use a massive edge-wound silver-plated rotary
>inductor from Pal Star (get one, they rock!) and real
>antennas of the proper size for the band -- not 1/10
>wavelength things and I homebrew my baluns from really
>big wire and lots of cores.

So, your situation is entirely different from the norm. In fact it
appears
that you might not even need the tuner.
A lot of comtemporary tuners use small inductors, a bunch of switched
fixed
value capacitors and modest variable capacitors. The built-in tuner in
my
TS-870 has 1 dB insertion loss into a dummy load!
The average guy who has bought into the magic ladder line fed antenna is
*not* using a tuner with edge-wound silver-plated inductors, but
something
like a mighty fine junk tuner and he's feeding a forty-meter dipole on
80
meters.
The only reason his doesn't burn up is the fact that the transmit duty
cycle is probably about 10-20% for the average operation if you figure
receive times and the low duty cycle of both SSB and CW.
>>Not that crappy efficiency can't happen, it can, but
>when you can't feel any heat rise inside the
>transmatch it's a big hint. Try holding onto a 100W
>incandescent light bulb! (don't).
>>rant off

Why are you ranting. Can't we hold a civilized technical discussion :)
Wes Stewart N7WS
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