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Old 22nd February 2004, 08:00 AM   #1
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Question How to improve FM reception?

Just wanting to cheaply/quickly/easily boost the pulling power of my tuner. Are those cheap RF amplifiers much use to boost RF reception any good?

Also, anyone know of a useful link for a DIY FM antenna and other ways to optimise reception ? (I'm not keen to modify the circuitry inside my tuner - the tuner's good, just the location is in a RF hole.

Cheers.
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Old 22nd February 2004, 09:29 AM   #2
Jax is offline Jax  Sweden
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A booster or antenna amplifier only helps if it has lower noise figure than the input stage in your radio. No booster beats a good antenna.

I found a link that looks good:
http://radio.meteor.free.fr/us/yagi_fm.html
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Old 22nd February 2004, 09:51 AM   #3
dhaen is offline dhaen  Europe
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Jax is correct when the booster amp is fitted at near the tuner.
If the booster is fitted at the mast-head (next to the antenna), there will be an improvement. This is because the loss of the downlead is subtracted from the noise. There is also sometimes an improvement in VSWR (matching).
At 100MHz 'ish the improvement will only be significant if the downlead is poor quality or very long.

You have got a roof antenna.... ?
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Old 22nd February 2004, 09:55 AM   #4
sreten is online now sreten  United Kingdom
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I've always been under the impression that an amplifier cannot
help a good good tuner except for exceptionally bad reception
conditions and a very good antenna is still needed, and a mast
head amplifier is the way to do it.

Or the device guaranteed to make other FM enthusiasts
green with envy, the remote mast head rotator.

My one book dealing with antenna's mentions circular polarisation,
and has a design for a freestanding vertical end fed half wave
antenna, its the most ergonomic indoor design I've seen.

(Basically a base with two 1/2" round vertical
sections, one 7.5ft long the other 2.5ft long)

What antenna are you using at the moment ?

sreten.
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Old 22nd February 2004, 10:26 AM   #5
Jax is offline Jax  Sweden
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Quote:
Originally posted by dhaen
If the booster is fitted at the mast-head (next to the antenna), there will be an improvement. This is because the loss of the downlead is subtracted from the noise.

Yes, that is correct but a good antenna still beats a masthead booster

It does not hurt to have both provided the quality of the masthead amp is good enough, not that wideband junk.
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Old 22nd February 2004, 05:52 PM   #6
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Here's a link to an easy to make FM antenna. I want to try this sometime but have not had the time.

http://zbconline.com/antenna.html
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Old 25th February 2004, 10:28 AM   #7
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Cool Imrpving FM Reception

Hi, the best booster is a multi-element antenna. The more elements the better. In the UK is a firm advertising in a UK Hifi journal that has a nice one. Sorry don't recall the names.
Use double shielded coax cable from antenna to receiver, as short as posssible in length to minimise losses.
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Old 26th February 2004, 03:29 AM   #8
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Hi,
Thanks for your input everyone who posted a reply. Much appreciated and exactly the info I was after. I think I'll have a go at building the antenna from the link that Scott Wurcer posted. Looks simple and cheap.

I'll post another reply to let you know how well it works once I've got around to building it.
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Old 26th February 2004, 05:10 AM   #9
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hello,

I have had excellent results with J-pole antenna's.

check out the following sites.

http://latham.dropbear.id.au/antenna/

http://www.mycal.net/old/projects/mpr/jpole.htm

the following site contains an excellent optimization program for your favorite radio frequency.

http://www.sedan.org/jpol.htm

and some pictures to see how a commercial application is done.

http://users.cis.net/kingpop/J-pole-pix.htm

Id go out to the roof to take a picture of the one I made, but it's raining in L.A. right now!



good luck


carl
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Old 10th August 2004, 08:17 AM   #10
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I've just built and installed a jpole as per one of the
examples, with a coax feed. My ham radio neighbor loaned
me his swr analyzer so I may be able to see if it's even
remotely tuned correctly for the FM band. I cut the elements
a little long so I'll have some room for tweaking.

I'm hoping the bandwidth is reasonably wide; I used 1/2"
copper tubing (gave me some practice soldering copper
tubing, too), though I might consider 3/4" on the next one.

Relatively easy project, and the results seem good for local
reception on the stations I wanted. Lots of multipath in
my location and a few stations seem to suffer as a result
with this presumably omnidirectional antenna, but thankfully
not the ones I wanted.

My first RF project in many years! Photos may eventually
follow (I wanna digital camera but can't afford a Canon Rebel)

--Damon
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