Re: First Base Station Antenna


Anthony Luscre <k8zt73@...>
 

But you are not calculating in the gain of the antenna or antenna height.
On 2M/440 on Diamond v200 that would be +6.2dB/+8.4dB.
Even if the power is a complete wash and equal to the rubber duck the height above ground will make a tremendous difference on VHF/UHF as well as being outside the house.

On Tue, Apr 26, 2022 at 6:06 PM Doug - AB7DG - Tacoma WA <schafer@...> wrote:
Well, Mark, I wonder about that.  According to https://kv5r.com/ham-radio/coax-loss-calculator/ , the loss in 100' of RG-8X coax at the upper end of the 70cm band (450MHz) is 8.281 dB if the SWR is 1.0:1, and increases to 8.455 dB if the SWR is 1.5:1. So with his 5 W HT connected to that coax, his output power is 0.743 W if SWR is 1.0:1, and only 0.714 W if SWR is 1.5:1. He loses 85 - 86% of his HT's power.

The specs for a Comet GP-3 base antenna show a 7.2 dBi gain on 70cm, and for a similar Diamond X50A a 7.2 dB gain on 70cm. So the gain from those base antennas does not make up for the coax loss (but if his HOA allows the antenna at significant height, he may improve his coverage nontheless).
https://cometantenna.com/amateur-radio/base-antennas/ba-dual-band/
https://diamondantenna.net/Product_Catalog/base_station.html

Mr. Moen might first try the inexpensive 34 - 37" HT antennaes, such as the Pryme AL-800 (5.6dB@440MHz) or the Diamond RH770 (5.5dB@430MHz).
https://www.aliexpress.com/item/32687288231.html
https://www.amazon.com/SAM-Male-Transceiver-Telescopic-Antenna-Extendable/dp/B0753GK1NS/

Doug Schafer, AB7DG, Tacoma. WA



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