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Wire in a uhf


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Guest Toally87

what have you got in your setup already?

 

vhf, model?

 

Intercom, Model?

 

and what model UHF would you like to use?

 

once we know a few more details we should be able to sort something out.

 

Toally

 

 

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OK.. UHF 5w radios draw about 2.5amps while transmitting so I would recommend at last 3mm diameter wire. I would recommend using 4mm cable if you need to run the wiring more than a meter as you will start suffering from electrical losses and this will affect the available transmission power.

 

Antenna placement - The antenna needs to be located in a vertical postion and the suggested placement is at least 3m from any other antenna. With aircraft it is important to use a very low gain antenna at the projected signal with the higher gain antenna's is very flat. Most shops will sell whats call a unity gain which will produce a round ball of signal (and reception) in all directions including downwards.. These antennas are about 153mm in length. (if you get stuck with a broken antenna just cut some cable to 153-157mm and remove the outer braid.. and plug the end into the socket.. Instant antenna at the right freqency)

 

Antenna mounting - Best postion would be on the underside of the aircraft as any metal will interfere with the reception. Try to make sure it is fairly centralised as this will produce the best result. If you are mounting it into a fibreglass body use a piece of tin foil (at least 24" square) on the back side of the antenna. This will give a fairly good ground plane for the signal reception and transmission.

 

Personally I have been using a GME 5w commerical grade handheld radio as I am able to program the 'private' channels that some of my clients use in the centre. I have made up an adapter so I can just plug my headset into it when I need to use the UHF and the radio just sits in the pocket next to me in a vertical position.

 

With a unity gain expect about a 8k range in flat country on the ground but in the air height is God. I have been able to call up a client from 145k at 6000' without an issue. (I have a telemetry unit that I installed just outside of Port Augusta on a hill top that gives a reliable 320km link using a directional antenna on ch22 at 5w - located at 2650' AGL with clear line of sight to the remote location)

 

Oh.. Dont forget to put a fuse (5amp) as close to the power source as possible.

 

 

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I have a X Com radio with the intercom and music imput built in and not sure which UHF yet. I am going to put a new hand grip in so the PPT buttons are in one place. I wouldalso have it the same as the music imput where it cuts out once aircraft radio kicks in.

 

Skip

 

 

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Guest Toally87

Skip are you happy having the input from the UHF on the music input (thats we're i'd put it cause i'm not so keen on music coming through my headset)?

 

If you're running a Coaxial cable or any Signal wire for that matter; were possible have it crossover any higher current power cables at 90degrees that way there will be no interference. i know this isn't alway possible, but when it is it helps.

 

will try make a nice easy circuit diagram for you in the next day or so. should be able to make the circuit using single pole double throw switches as aposed relays (take one more thing that can fail out of the loop)

 

Toally

 

 

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HI Toally87

 

Yes I am quite happy to have it on the music imput as I bought the plane with it already in, and thank you for all the trouble you are going to.

 

Skip

 

 

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  • 7 years later...

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