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Old July 7th 07, 02:51 AM posted to rec.radio.amateur.antenna,alt.tv.tech.hdtv
G-squared G-squared is offline
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First recorded activity by RadioBanter: Jul 2007
Posts: 7
Default Front-to-back ratio for UHF antenna

On Jul 6, 5:11 pm, szilagyic wrote:
On Jul 6, 3:14 pm, G-squared wrote:

Your antenna has around 8 dB more gain than mine and you're

closer to
some of the stations. How long is your cable? If you have Line Of
Sight to the towers you shouldn't need much gain at all,

basically to
make up for cable losses like 5-10 dB. If you're behind

obstructions,
that game changes a lot though.


Instead of the 8275 I would use the AP-8700. There is less gain

but
more headroom and I suspect that will be more of an issue.


http://www.winegard.com/offair/preamps.htm


GG


Hello and thanks for the reply!

We are mainly concerned with stations that are all between 35 & 45
miles away (don't care about the one that's 15 miles away); and

some
seem to be weak as current signal strength is about half, and they
drop from time to time. Given this, would the AP-8275 work well,

or
would you still recommend the AP-8700? I have an attenuator just

in
case.

I really appreciate your feedback on this..... Thank you!!!

--
Chris


Again, I'm at 35 miles with line of sight to the transmitters and a
low gain antenna. The reason I suggested the 8700 is the reduced gain
compared to the 8275. Keep in mind that amplifiers are not a panacea
and are wideband devices. Just because the local (15 mile ) station is
on whatever channel doesn't mean it can't cause overload issues _many_
channel numbers away. At 35 miles with good coax 100-200 feet, I
wouldn't expect to need any amplifiers at all, much less 29 dB worth
but if you believe you need it, the 8700 should be more tolerant of
overload issues. You might even need to put the attenuator _ahead_ of
the amplifier to keep _it_ from overloading.

GG