Back of set antenna on UHF MotoTRBO mobile

[Anderegg]

Setting up an XPR4550 on an Astron power supply indoors. Was planning on programming it down to 1-2 watts (whatever minimum power is) and throwing some sort of back of set right-angle BNC antenna solution on the back, so as to not irradiate the humans sitting next to the rig.

Any issues with this? Not sure how mobiles and handheld antennas match as far as grounding needs go...my only experience is with using NMO no ground plane antenna versions for special cases. Radio won't be used hardly ever, just a backup for if cell service goes down.

Paul

 

[jeepsandradios]

Dependso n use case but I've done that for receive only with no issues. I think minimum power is 5 watts on the mobile so in thoery your same as a handheld but have no ground plane for tx. I'm sure folks are out there doing the same thing but personally I'd just drop a mag mount nmo 1/4 wave on it and put on something metal.

 

[alcahuete]

Here is the setup I have in my bedroom. Don't need it to be super complex or even work very well. I just use it for receive mainly, and to transmit around the property and into a repeater. Of course the 1/4 waves will especially not work well (mainly the one just hanging on the side of the radio), but that's fine.

1/4 wave antenna on the mag mount
1/4 wave antenna on the side of radio
1/2 wave black antenna

 

[Anderegg]

Here is the setup I have in my bedroom. Don't need it to be super complex or even work very well. I just use it for receive mainly, and to transmit around the property and into a repeater. Of course the 1/4 waves will especially not work well (mainly the one just hanging on the side of the radio), but that's fine.

1/4 wave antenna on the mag mount
1/4 wave antenna on the side of radio
1/2 wave black antenna

We are actually buying one of those Astron power supplies that has the custom cover for the XPR4550, so I think we may be able to use an existing NIB (in our junk box) NMO mount out of storage, and pop one of those L brackets on the side of the housing. Would a non-ground-plane antenna be necessary to not burn out the amp, or you think some stupid new style UHF pucktenna (more junk we have in a box) would be fine at 2 watts (low power spec for the XPR in Connect Plus trunking) infrequent use? Not so much concerned about hitting the system as handhelds are full signal indoors here, just don't want to F around and fry something due to inappropriate grounding or some other nonsense.

Paul

 

[alcahuete]

We are actually buying one of those Astron power supplies that has the custom cover for the XPR4550, so I think we may be able to use an existing NIB (in our junk box) NMO mount out of storage, and pop one of those L brackets on the side of the housing. Would a non-ground-plane antenna be necessary to not burn out the amp, or you think some stupid new style UHF pucktenna (more junk we have in a box) would be fine at 2 watts (low power spec for the XPR in Connect Plus trunking) infrequent use? Not so much concerned about hitting the system as handhelds are full signal indoors here, just don't want to F around and fry something due to inappropriate grounding or some other nonsense.

Paul

I haven't checked the SWR in a long time, but it wasn't terrible when I put it on. Just obviously not efficient.

While the 1/4 wave on the mag mount isn't the best ground plane, it's somewhat close, which will definitely work better than the L bracket antenna. The black antenna I use on one of the radios is a 1/2 wave that doesn't require a ground plane, but will work better with one.

All works well for my use case though. You'll probably be fine too at those power levels.

 

[mmckenna]

I've got a number of small stations set up like that on my trunked system.

15 watts, and I always use some form of external antenna to get it away from the users. Usually it's a mag mount, 1/4 wave antenna, and stick it on a file cabinet, or book shelf.

2 watts is probably fine on top of the power supply cabinet. The antenna will be happier with a ground plane. Even 'no ground plane' antennas will work better with one.

 

[Anderegg]