[R-390] Antenna question

[blw]

Tom,

Let me get this straight. I'm not trying to be ornery. Are you saying that
CAT-5 ethernet cable is better than coax? Ethernet cable isn't that
expensive. I bought a 100' roll at Rat Shack to run a long line under the
house for networking to the router. I did discover that coiling the extra
10' of cable at the computer slowed the data down to a crawl. I lopped off
the extra cable, made a new connector, and Internet speeds jumped up to
where they were supposed to be. I wonder why coiling CAT-5 will slow things
down so much.

I would have to feed 2 dipoles. I guess the extra twisted pairs would be
good for additional antennas this fall.

Okay, here is another problem. I read the RFI thread a few weeks ago and
found it interesting. I had no problems then. Very quiet with 2 computers
within a few feet of the radios. Now, I seem to be having a new problem. The
new TV in the den is causing light RFI every 15 kc up and down the bands.
The TV is 3 rooms away!!! My coax runs outside about 20' away from the
blasted thing, but it would seem to not be the source of the problem. Any
ideas before I tell my kid the new TV is broken at night and to go use the
one in his brother's room?

I don't transmit, so receiving is the only problem here.


Barry


> On Thu, 18 Jul 2002 08:20:26 -0500 "Scott, Barry (Clyde B)"
> <cbscott@ingr.com> writes:
>> What is/was the recommended "standard" antenna and feedline for the
>> R390A? 
> 
> There is no recommended standard because the radio was
> used in so many applications. The only installation documentation
> I have ever seen showed unbalanced was for whip antennas and
> the balanced for a doublet (if you are under fifty read "dipole")
> fed with twisted pair. I use twisted pair and even CAT5 cable
> with multiple dipoles and get excellent results with good zeroing
> of the antenna tuner on all bands. The twisted pair also has the
> added (and primary) advantage of making the antenna system
> immune from noise not detected by the antenna elements, such
> as the PC computers in the shack that everybody is always
> complaining about, because twisted pairs cancel out induced
> currents...which is why the phone company can smash thousands
> of them together in a bundle, and why your CAT 5 cable works
> at 100 Mhz without any shielding...imagine that.
> 
> Running an unbalanced feedline invites local noise, and using a
> balun to then feed it into the balanced input accomplishes nothing
> more than adding more loss and yet another tuned artifact into the
> system. If you really want the extra stage gain on the unbalanced
> input, do the Navy mod, which grounds one side of the balanced
> input (making it unbalanced) and feeding the other side out the
> unbalanced bulkhead connector. That gives you an unbalanced
> 75 ohm system which not only allows you to use cheap TV coax
> like RG-59 or RG-11, but also just happens to be the impedance
> at the feedpoint of a resonant half wave dipole.
> 
> WOW...Isn't that exciting? Now, listen to this...magnified ninety
> two thousand times, the sound of the viscious Afgan panther lizard
> visiting the chemist...
> 
> Twisted Twit Hammarlund