Base antenna on OpenSpot as simplex link

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Posts: 10
Joined: Sun Nov 19, 2017 9:27 pm
Location: Norway

Base antenna on OpenSpot as simplex link

Post by okris »

Hi all!

I did a test connecting the OpenSpot to a base antenna. I used "a lot" of different adapters from my drawer that started with sma and via bnc ended up with SO-259 going into the Coax cable :D Then 30 metres of Westflex 103 before it all ended in a Diamond X-510 on my roof - 90 metres above sea level.

I did not expect any signal reaching the antenna. 19.9 mW is not much.
To my surprise, it had a range of 2 km in a straight line. (With the original rubber duck it has a range of amazing 500 metres).

Since it is allowed (in our country) to put up a simplex link at my own qth (repeaters only requires a special license), I decided to make the OpenSpot a simplex link accessible to other hams in the area. There are no DMR repeaters in this part of the country at all, so a simplex link would be an ok substitute for mobile use.

I already have a dmr amplifier ready for testing to boost the range a bit.

Does anyone else have any experience with this? Would be fun to hear from others that are doing the same thing.


Posts: 54
Joined: Mon Oct 16, 2017 2:05 pm

Re: Base antenna on OpenSpot as simplex link

Post by K9IUQ »

I too have been amazed at the range of the openspot transmitter. I replaced the rubber duck that came with the openspot with the long rubber duck antenna that came with my MD-380. I use the short duck that came with the MD-380 on the radio. With this I am able to walk my dog 1/2 mile from the house and still have perfect copy, Not too bad for 20 mw and 2 rubber ducks. I do have the Openspot on a high shelf in my radio room and the house is on a hill.

I too have a Diamond 510 antenna, but have not (yet) used it on the openspot. The 510 as you know is a very high gain (great) antenna. You are probably losing lots of power in all those adapters, especially at UHF. I use LMR-400 on the Diamond 510. Maybe I will try the 510 on the openspot and see what kind of range I get. :)

Stan K9IUQ

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Joined: Thu Nov 09, 2017 9:33 pm

Re: Base antenna on OpenSpot as simplex link

Post by dj3le »

Somw weeks ago I tested a 10W amplifier driven by the openspot to my X510H in 6 meter above ground level. The trx was my Motorola DM4600 fixed mounted in the car with a quarter wave length antenna. Max. distance was 15km to work over the Openspot.

73 de Hans DJ3LE

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Joined: Mon Dec 26, 2016 5:05 pm

Re: Base antenna on OpenSpot as simplex link

Post by kg4vdz »

I have done this exact thing I purchased a dmr amplifier on ebay 50 watt version I use my openspot on outside antenna on my tower about 50 feet up and I can get about 14-15 miles the problem I see some users having is they are buying these low powered amplifiers on ebay like the red 13 watt version and the others they are only transmitters they disconnect the antenna when they are receiving I have confirmed this with the ebay seller also but I have some youtube videos on this subject search my call on youtube and you will find them there is one amplifier on ebay for dmr that does work great with the openspot the openspot only being 20mw the power out from my 50 watt amplifier is only 15 watts but i can use the openspot in my area for about 15 miles with no problem that is with my mobile dmr radio in my car back to the open spot so beware of some of the small dmr amplifiers on ebay like the 13 watt version as they will not work you will hear the open spot great but you cant get back to it 73's kg4vdz

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