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Re: Stupid Questions from a newbie



Tim,

In my opinion, the only "stupid" question is the one which remains
unasked.  You're doing fine.

"Timothy S. Zibrat" wrote:
> I have a Drake 2880 downconverter that I finally got around to modifying and
> getting ready to install.  I have a R. Myers SB-32DX dish antenna.  What
> kind of feedline can I run from the downconverter to my station?  
You do have a lot of questions, but I'll attempt to wade in.  As usual,
use the lowest loss feed line you can beg, or buy.  However, since you
are running the 144 IF frequency down to the shack, the losses will be
much less than if you had the converter in the shack. 9913, LMR, and
others have good loss figures.

Judd, W1PEA, talked me into covering my Myers disk with brass mesh.  He
asserted the gaps in the "charcoal grill" don't capture all the signal. 
I THINK I noticed a 3 dB gain.  My measurements were made using the sun
as a source, and 3 hours difference in time.  The path may have changed
in that time.

> Can I, or should I run something like RG8X, or the RG6 cable
> TV cable?  What's the impedance mismatch going to do to me if I use the RG6?
Why?  Hard line can sometimes be "begged" from your local cable
installers as spool ends.  If you aren't concerned with cutting the line
to a specific length, the line will show an SWR of 1.5:1.  If you use 75
ohm line, (such as hard line), AND you cut the line to an exact multiple
of 1/2 wavelength, the impedance will be repeated.  That is, the radio
end of the coax will show the same impedance as the load end.  If your
load is 50 ohm, you will see a flat SWR.

> Will RG8X fit in an F connector?  What if I got one of those California
> Preamps?  Do I need one?  I'd like to be ready for P3D and maybe try to
> receive the UO-11 Mode S beacon.  Feedline length: about 50'.
I would probably use a good gold plated F to N adapter, and put N
connectors on your coax.  The new 1 piece solder on types are
wonderful!  A preamplifier at 2.4G will most certainly help.  If you
have the funds, by all means get one.

> I've heard different opinions on feedline for 435 and 144MHz.  I plan on
> picking up some 9913Flex, but I heard that 8214?? is much more flexible and
> has negligible losses (maybe for HF but for V-UHF as well?), and is cheaper.
> I've also heard that 9913 is prone to water infiltration over time.  Is this
> true as well?  If so, how do I prevent it?  Feedline length: about 50'.
50' of 9913 will serve you well.

> Where can I get a good deal on feedline/rotor cable?
Just look for some good Belden wire.  Search the Internet or your Yellow
Pages.

> Should I run my cables through some kind of conduit to protect them from UV?
More trouble than it's worth.  Most good cable is UV resistant.
 
> My 435/144 antennas are currently configured for RHC polarization.  Is this
> the preferred polarization for all current satellites?
Switchable polarization sense is desirable on MOST of the birds.  If you
are receiving a LHCP signal with a RHCP antenna, your loss could be
somewhere around 20 dB.

> What's a good weatherproof method to use on the connectors?
Good 3M electrical tape, followed by black coax seal, is what I use.  I
like to slip a piece of heat shrink tubing over the coax before
attaching the connector.  After soldering, I slip it over the junction
between coax and connector and shrink.

Feel free to ask more questions.  The collective knowledge and
willingness to help on this reflector is awesome!

73, Mike in Fort Myers, FL
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