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Old 27-Feb-2015, 6:22 PM   #1
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Join Date: Feb 2015
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Coax lengths from 2 antennas to Preamp

This is the equipment that I am dealing with @ my brothers location. 30 foot of rohn tower with about 7 or 8 feet of mast above tower with a ham 4 rotator in tower. It has 2 antennas mounted in the same direction on mast pipe. They may be about 3 feet apart verticaly. The top antenna is a Winegard hd-9095 and the lower antenna is a Winegard ya 1713. These antennas are connected to a dual input preamp. The preamp is a Winegard AP 2870 with seperate input for the vhf and for the uhf antennas. I just cut coax to fit to from antennas to amp. I am wondering if the length of coax from antenna to preamp should be the same? Something else I was wondering is since this pre amp has about 2.9 db of noise on both uhf and vhf with 17 db gain on vhf and 19db of gain on uhf would I be better off with a different preamp and a low loss combiner or diplexer? This is the location and I am just not satisfied with results. I have drop out on some of the local stations and I am not sure what is going on. I would appreciated any suggestions Thanks John
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Old 27-Feb-2015, 7:26 PM   #2
Tower Guy
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Location: Delmar, NY
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You are having problems with too much signal for a preamp. Get a UVSJ instead. The coax lengths won't matter.
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Old 28-Feb-2015, 2:51 AM   #3
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Location: Greater Seattle Area
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Unless there are obstructions such as trees or structures to contend with...

I agree, the signal levels shown in your TVFR strongly argue against the use of any amplification. (only if you are dealing with unusually long cable runs and splitting losses would I consider using a distribution amplifier.)

I would expect a smaller, less directional antenna such as the RCA ANT-751R would be a far better fit to the signal conditions shown. No amp or combiner would be needed either. (Even unamplified rabbit ears should do well in these conditions provided the building construction doesn't block signals.)
If the well is dry and you don't see rain on the horizon, you'll need to dig the hole deeper. (If the antenna can't get the job done, an amp won't fix it.)

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Last edited by GroundUrMast; 28-Feb-2015 at 2:54 AM.
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coax length

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