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I think I'm going to try to shunt feed my 72 foot tower with a gamma =
match for 160 as per various books and articles. According to these =
sources, I'm going to need a 250pf variable capacitor. I'll be running =
full power. I have several questions:
1. What should be the voltage rating of the capacitor?
2. Can it be an air variable or must it be a vacuum variable?
3. Do you really need a variable or can you use less expensive =
fixed ceramic capacitors and get a pretty good approximation?
4. Can anyone suggest reputable suppliers of these types of =
capacitors?
5. I have a motorized tower, TX-472MDP, which I keep retracted most =
of the time to be neighbor-friendly. Will shunt feeding work ok or will =
it be "twitchy" because of the lack of bonding between sections and/or =
because I won't be able to keep the gamma wire really tight?
Thanks in advance for any help you can give me.
Gerry Bay, W1XY
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<DIV><FONT color=3D#000000> I think I'm going to try to =
shunt feed my=20
72 foot tower with a gamma match for 160 as per various books and=20
articles. According to these sources, I'm going to need a 250pf =
variable=20
capacitor. I'll be running full power. I have several=20
questions:</FONT></DIV>
<DIV><FONT color=3D#000000> 1. What should be =
the voltage=20
rating of the capacitor?</FONT></DIV>
<DIV><FONT color=3D#000000> 2. Can it be an air =
variable=20
or must it be a vacuum variable?</FONT></DIV>
<DIV><FONT color=3D#000000> 3. Do you really =
need a=20
variable or can you use less =
expensive =20
fixed ceramic capacitors and get a pretty good =
approximation?</FONT></DIV>
<DIV><FONT color=3D#000000> 4. Can anyone =
suggest=20
reputable suppliers of these types of capacitors?</FONT></DIV>
<DIV><FONT color=3D#000000> 5. I have a =
motorized tower,=20
TX-472MDP, which I keep retracted most of the time to be=20
neighbor-friendly. Will shunt feeding work ok or will it be=20
"twitchy" because of the lack of bonding between sections =
and/or=20
because I won't be able to keep the gamma wire really =
tight?</FONT></DIV>
<DIV><FONT color=3D#000000></FONT> </DIV>
<DIV><FONT color=3D#000000>Thanks in advance for any help you can give=20
me.</FONT></DIV>
<DIV><FONT color=3D#000000></FONT> </DIV>
<DIV><FONT color=3D#000000>Gerry Bay, W1XY</FONT></DIV></BODY></HTML>
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