Grind down the elements on a Yagi Beam???

SCPD · Feb 12, 2015

I monitor and am a feed providor for Clark County Ohio and with the Marcs system, they are soon making a switch to the newer IP which is in a lower range 774. mhx specifically is where I will be monitoring. I use a beam Yagi in the 800 range and I bought a cell phone amplifier antenna that goes from 800 825 850 range, can I take these two antenna and trim up the element to be able to grab the signals better in the range I need.?? And what would one suggest I do when cutting or grinding down the elements. The 800-850 is a10 DB gain?
I am using 50 foot runs of quality RG6. Suggestion would be appreciated.

phask · Feb 12, 2015

Should be able to cut mist any aluminum element with a good pair of wire cutters. Your horizontal spacing will be off, but probably not matter that much.

prcguy · Feb 12, 2015

The elements would need to be longer for 774MHz. The antenna is only a little out of range at 774 and will probably work ok as it is.

Upgrading your coax or placing an amplifier with band pass filter right at the antenna would make a much bigger improvement than tweaking the antenna.
prcguy

sspnelson said:
I monitor and am a feed providor for Clark County Ohio and with the Marcs system, they are soon making a switch to the newer IP which is in a lower range 774. mhx specifically is where I will be monitoring. I use a beam Yagi in the 800 range and I bought a cell phone amplifier antenna that goes from 800 825 850 range, can I take these two antenna and trim up the element to be able to grab the signals better in the range I need.?? And what would one suggest I do when cutting or grinding down the elements. The 800-850 is a10 DB gain?
I am using 50 foot runs of quality RG6. Suggestion would be appreciated.

ab5r · Feb 12, 2015

I doubt that you would notice a difference from what you already have.

KC4RAF · Feb 12, 2015

As 'prcguy' posted.

Cutting the antenna will place it in a higher frequency range. But if you use it as he posted, you probably will receive the 7xx hundred freqs ok.

popnokick · Feb 12, 2015

Why not use a UHF TV antenna? The 700 mHz Public Safety band was carved out of the recent move by TV broadcasters to HDTV and off of the 700 mHz channels they formerly occupied. This means many TV antennas (which are Yagis) have lots of gain, cover the right frequencies, and are inexpensive compared to purpose-built 700 mHz commercial Yagis. You'll need to rotate the antenna so that the elements are vertical (pointing up and down) rather than horizontal (as with a normal TV antenna installation), since the 2-way comms you'll be listening to are vertically polarized.

majoco · Feb 12, 2015

+1 on popnokicks suggestion - I use cut-down TV antennas for all sorts of frequencies. Now that we've gone to UHF digital here, people are scrapping their old antenna's so you can pick them up for nix.

If necessary to can disassemble them and re-engineer for different frequency bands - they're usually held together with pop rivets.

http://forums.radioreference.com/at...pics-videos-your-swl-antenna-dscf0441-sml.jpg

SCPD · Feb 12, 2015

Like ab5r and rafdav said, using it as is will work out just fine.
You're just receiving.
I'd even venture to say transmitting on it at 774 Mhz would not give you too bad of a bad match.

Grind down the elements on a Yagi Beam???

SCPD

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phask

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prcguy

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ab5r

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KC4RAF

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popnokick

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majoco

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SCPD

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