Which coax for discone?

Which coax for discone?

Post by Hiran C. Fernan » Sat, 03 Dec 1994 14:40:49

I am planning to put a Radio Shack discone antenna on my roof for my
Pro-2006 scanner. For approximately a 50 foot run, which type of coax
should I use, RG-8 or RG-8/M? I had read I should use 50 ohm coax, but I
noticed that these two are 52 ohm. Will that damage my scanner?

The Radio Shack discone is $60, and I noticed that Icom sells a similar
one for $100 and $120 with 80 feet of coax. Is the Icom superior to the RS
for the difference in price, or are they relatively similar in performance.

Again, thank you very much for your help. I really appreciate it as a
scanner novice. I try to read to learn as much as possible, so as not to
disturb this group with basic questions, but sometimes I find limitations
in my resources. You can email me directly if you'd like.

 
 
 

Which coax for discone?

Post by David Hor » Sun, 04 Dec 1994 04:43:15



Quote:>I am planning to put a Radio Shack discone antenna on my roof for my
>Pro-2006 scanner. For approximately a 50 foot run, which type of coax
>should I use, RG-8 or RG-8/M? I had read I should use 50 ohm coax, but I
>noticed that these two are 52 ohm. Will that damage my scanner?

Nope.  The ohms stuff is only critical for transmitting.  75 ohm coax
will work fine too.  In fact, 75 ohm will do for transmitting too as
long as you aren't running a lot of power and you have a fairly modern
rig....but that's another topic.  Since you have a 50 foot run of it,
get something "low loss" since you'll be attenuating UHF frequencies a
bit with a 50 foot run.  With 50 feet, RG8 will do but RG58 might not.

Quote:>The Radio Shack discone is $60, and I noticed that Icom sells a similar
>one for $100 and $120 with 80 feet of coax. Is the Icom superior to the RS
>for the difference in price, or are they relatively similar in performance.

Get one with the vertical whip if you want good results on freqs below
100 MHz.  Otherwise, the Rat Shack antenna will do fine above 100 MHz.

Quote:>disturb this group with basic questions, but sometimes I find limitations
>in my resources. You can email me directly if you'd like.

It is a fairly frequent question, but one I'm sure many folks need an
answer to periodically.


Plano, Texas   (not your average plain-O town :-)

 
 
 

Which coax for discone?

Post by Darrell A. Laro » Mon, 05 Dec 1994 04:53:19


Quote:>I am planning to put a Radio Shack discone antenna on my roof for my
>Pro-2006 scanner. For approximately a 50 foot run, which type of coax
>should I use, RG-8 or RG-8/M? I had read I should use 50 ohm coax, but I
>noticed that these two are 52 ohm. Will that damage my scanner?

>The Radio Shack discone is $60, and I noticed that Icom sells a similar
>one for $100 and $120 with 80 feet of coax. Is the Icom superior to the RS
>for the difference in price, or are they relatively similar in performance.

I am running RG-6U on my RS Discone. You can also run Belden 9913 if you
are feeling rich! I don't worry too much about line impedence on feed-line
as it really doesn't present a problem with recievers. It has 100% shielding
and very, very low loss (esp compared to RG-58 that Shack will try to sell)
RG-8U (foam dielectric) is what I would choose if you are stuck with RG-8

cheers

--

 "..Just hitchhiking along the info highway..."  

 
 
 

Which coax for discone?

Post by Julian C Gramm » Mon, 05 Dec 1994 10:16:46



Quote:>I had read I should use 50 ohm coax, but I noticed that these two
>are 52 ohm. Will that damage my scanner?

No, because you're not transmitting (ignoring the IF bleed from the
tape-out phono). What is more important is that you won't even
notice any appreciable difference in Rx S-level, because 50 Ohms is
a nominal value only, and 4% is an acceptable tolerance. In fact by
the time it's been nailed to the wall, folded back upon itself
etc., thus altering its actual impedance further, in most cases
it'll still perform adequately.

Toodle pip!

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Which coax for discone?

Post by Marc B. Gra » Wed, 14 Dec 1994 23:08:34

For a discone antenna, the BEST coax to run is 9913, which could be
expensive and hard to work with, but it is the best, especially if you
have a long run.  Additionally, 52 ohm or 50 ohm is of little consequence
since you are not transmitting.

--
Marc B. Grant

Voice Mail: 214-246-1150
Amateur Radio N5MEI