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GE MPA Shoulder Mic Antenna

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jfab

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Hello all-
I have an800mhz MPA and recently bought a GE shoulder mic for it. I want to get an antenna for the shoulder mic (it has a jack on top for one). Does anyone know where I can get a stubby 800mhz antenna for this shoulder mic? Maybe a model number or something?

Also, does putting an antenna on the shoulder mic really make that much of a difference? How much will it improve my reception? The city I am trying to pick up is pretty far away, and I can pick it up fine at my house, just want to see if I can boost the signal a little bit around town.

Thanks!
 

mitaux8030

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With a portable sitting on your belt, your body proximity to the antenna will detune the antenna and cause less signal to be received. When networks are planned, we usually figure on this loss to be an average of 10dB... quite significant. Personally, I'd be budgeting for 15dB.
However when you pull the portable off your belt and hold it up to your face, the antenna is a little more in the clear, that is not so close to your body and so the antenna performs better... still not optimum but definitely better than when on your belt.

The idea of the shoulder mic is to get the antenna away from your body and always have it somewhat out in the open. Again this arrangement isn't optimal, but its better than being on the belt of the user. However counting against this is the loss of the tiny feedline in the mic cord, pulling things back a few dB.

The main advantage of this arrangement is getting the speaker near the users ears, but then any shoulder-mic will do this of course. However a normal shoulder-mic will keep the radio on the belt of the user while they transmit and the detuning of the antenna effect comes into play then, causing a dramatic reduction in the usable range of the radio system.

In your situation, if you had your portable on your belt with a full 1/4 wave whip receiving, but off your belt and near your face to transmit, you'd have the optimum worst standby RX but optimum best TX.
If you replaced this with a stubby helical antenna on a shoulder-mic then you'd have slightly sub-optimum RX & TX due to the lower gain stubby, but being clear of your body. You could improve this by 3dB by using a full 1/4 wave instead of a stubby on the shoulder mic.

If you're looking for the absolute best RF performance, then get yourself a 1/2 wave end fed antenna and hold the radio in your hand. A 1/4 wave elevated feed works just as well (some say a little better but I'm not convinced of that) but is slightly longer in length and not as flexible, so the 1/2 wave end fed is more convenient in my view.
If you must get a shoulder-mic, then the best performance will be realised with a mic that has a short straight cord, not a curly cord type, and using a 1/4 wave antenna on the mic. It's a little less convenient than the stubby for sure, but the stubby antenna knocks off about 3 to 4dB of performance, and combined with the mic cord antenna feedline loss you're starting to loose quite a bit.
Even less physically convenient would be fitting the shoulder mic with a 1/2 wave end fed antenna... but it would give you about 3dB over the 1/4 wave, potentially even more in this situation.

In the end, which way you should go is determined by how you'll use the radio and what level of convenience you want (or inconvenience you're prepared to accept) versus the RF performance you need.
 
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foxracr10

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When I used my MPA i moved the antenna from the top of the radio to the top of the mic. Seemed to rx and tx about the same. Maybe rx was a little clearer. My speaker mic also had the straight cord on it if that makes a difference.
 

jfab

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When I used my MPA i moved the antenna from the top of the radio to the top of the mic. Seemed to rx and tx about the same. Maybe rx was a little clearer. My speaker mic also had the straight cord on it if that makes a difference.
What antenna were you using? I tried this but the jack on the mic is too small for the antenna on top of the radio..
 

foxracr10

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Jan 19, 2008
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Coatesville, PA
It was a standard 3inch rubber antenna that came on top of the MPA. I just unscrewed it from the radio and it screwed right into the speaker mic.

I'll see if i can dig up some pics of the mic and radio.

I dont get to carry an 800 portable anymore :(
 

n8_1

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Jul 15, 2011
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Outstanding review and opinion

With a portable sitting on your belt, your body proximity to the antenna will detune the antenna and cause less signal to be received. When networks are planned, we usually figure on this loss to be an average of 10dB... quite significant. Personally, I'd be budgeting for 15dB.
However when you pull the portable off your belt and hold it up to your face, the antenna is a little more in the clear, that is not so close to your body and so the antenna performs better... still not optimum but definitely better than when on your belt.

The idea of the shoulder mic is to get the antenna away from your body and always have it somewhat out in the open. Again this arrangement isn't optimal, but its better than being on the belt of the user. However counting against this is the loss of the tiny feedline in the mic cord, pulling things back a few dB.

The main advantage of this arrangement is getting the speaker near the users ears, but then any shoulder-mic will do this of course. However a normal shoulder-mic will keep the radio on the belt of the user while they transmit and the detuning of the antenna effect comes into play then, causing a dramatic reduction in the usable range of the radio system.

In your situation, if you had your portable on your belt with a full 1/4 wave whip receiving, but off your belt and near your face to transmit, you'd have the optimum worst standby RX but optimum best TX.
If you replaced this with a stubby helical antenna on a shoulder-mic then you'd have slightly sub-optimum RX & TX due to the lower gain stubby, but being clear of your body. You could improve this by 3dB by using a full 1/4 wave instead of a stubby on the shoulder mic.

If you're looking for the absolute best RF performance, then get yourself a 1/2 wave end fed antenna and hold the radio in your hand. A 1/4 wave elevated feed works just as well (some say a little better but I'm not convinced of that) but is slightly longer in length and not as flexible, so the 1/2 wave end fed is more convenient in my view.
If you must get a shoulder-mic, then the best performance will be realised with a mic that has a short straight cord, not a curly cord type, and using a 1/4 wave antenna on the mic. It's a little less convenient than the stubby for sure, but the stubby antenna knocks off about 3 to 4dB of performance, and combined with the mic cord antenna feedline loss you're starting to loose quite a bit.
Even less physically convenient would be fitting the shoulder mic with a 1/2 wave end fed antenna... but it would give you about 3dB over the 1/4 wave, potentially even more in this situation.

In the end, which way you should go is determined by how you'll use the radio and what level of convenience you want (or inconvenience you're prepared to accept) versus the RF performance you need.
Thank you. Although, I am a Motorola radio user, this was a great review and very helpful to me as a passer-by in the thread. I am currently struggling with the same decision of going to a speaker mic with antenna since experiencing some TX issues as of late with my CP200. This gives me some good information to ponder.
 
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