Batboard

Hi All,

just got my first EVER Motorola radios a couple of months ago. a few GP328's. was doing some experimenting with them in a small room, took the antennas off and tried to transmit/receive with no antennas on the radios. the radios TX/RX'ed with no antennas attached, my question is if you can TX/RX perfectly fine without antennas, than whats the point of having antennas???? it doesnt seem like there would be a use for them!!!??? can anyone explain to me? (yes i kno im a retard, so dnt laugh )

Well, I hope you didn't destroy the transmitter in those radios...

You MUST have an antenna attached to the radio or else it's going to fry the radios transmitter.

nah luckily it didnt fry the transmitter =phew= glad i learnt that one fast

losangelescop wrote:Hi All,

just got my first EVER Motorola radios a couple of months ago. a few GP328's. was doing some experimenting with them in a small room, took the antennas off and tried to transmit/receive with no antennas on the radios. the radios TX/RX'ed with no antennas attached, my question is if you can TX/RX perfectly fine without antennas, than whats the point of having antennas???? it doesnt seem like there would be a use for them!!!??? can anyone explain to me? (yes i kno im a retard, so dnt laugh )

lac - there is another way that you can use those radios without antennas - it calls for COAXIAL CABLE between the two radios BUT I don't suggest that you actually try that one at home, by yourself, unsupervised!!!!

Gee I remember doing that in the Melbourne Underground.
We joined 25 watt transmitters together with coax.
It worked great, I used to do it the mines up north as well.
Ok I admit it was leaky feeder and was very calculated in terms of losses and duplexers but it worked great

Bruce1807 wrote:Gee I remember doing that in the Melbourne Underground.

I wanted to do that, as a kid, using the CABLE TV drop; never did, would have used CB rigs to do so at that time!

Should have done it, as a kid that is , and gotten 'the experience'; I would have enlisted the 'help' of three or four others both near and far to report if they could have 'received' me.

We did it proffesionally when the Underground (railway system was built)
We had repeaters going into splitters and then duplexers so we could feed rx/tx in both directions in the tunnels on one peiece of leaky feeder each way.
It was a bit of an act and in the middle was a join with an attenuator calibrated to whatever value was needed so that txers wouldn't zap each other.

I bought the same idea with me when I started underground mine communications and the old school head of engineering thought I was mad. I sat down with him over several beers and we did the calculations for one of the horizontal shafts we were having some problems in.
He agreed in principal but it still took him another three months for the go ahead. It then became common practice in any long shaft that required more than 1 repeater to reach the main shafts.
Every second Sunday we worked the pits to extend the leaky feeder system into the new areas.
Man I was young but boy was I paid well.
Shame I p@#sed most of it down the toilet!
Oh well I grew up eventually

We did it proffesionally when the Underground (railway system was built)
We had repeaters going into splitters and then duplexers so we could feed rx/tx in both directions in the tunnels on one peiece of leaky feeder each way.
It was a bit of an act and in the middle was a join with an attenuator calibrated to whatever value was needed so that txers wouldn't zap each other.

I bought the same idea with me when I started underground mine communications and the old school head of engineering thought I was mad. I sat down with him over several beers and we did the calculations for one of the horizontal shafts we were having some problems in.
He agreed in principal but it still took him another three months for the go ahead. It then became common practice in any long shaft that required more than 1 repeater to reach the main shafts.
Every second Sunday we worked the pits to extend the leaky feeder system into the new areas.
Man I was young but boy was I paid well.
Shame I p@#sed most of it down the toilet!
Oh well I grew up eventually

so what happens when you use an antenna on a radio that is rated for a different band (e.g. a 403-470 MHz antenna on a 480 MHz radio channel, or a VHF antenna on a UHF radio?

Not only will the radio be highly inefficient as to what it is suppossed to do , the strain on the power amp will finally kill it.
a 403-470 on a 490 probably won't cause much but on a vhf the damage will occur every time you tx.
As a health & Safety issue you arecreating rf issues that are non complient within the radio

losangelescop wrote:so what happens when you use an antenna on a radio that is rated for a different band (e.g. a 403-470 MHz antenna on a 480 MHz radio channel, or a VHF antenna on a UHF radio?

Your range for transmitiing ad receiving will be greatly reduced, an over time you'll destroy the PA. Many radios with blown PA's show up with wrong antennas. Look for the proper antenna/color code.

Transmitting without an antenna is the dummest thing you could ever do with your radios. Dumb Dumb Dumb.

Depending on how long you keyed your radios without antennas, the radios might have already suffered damage to the PA section. Someday the radios might stop transmitting out-of-the-blue because of what you did with them. Your new radios might have come out of the box at 4 watts power output, now they may be transmitting less power now.

The PA's final output transistor consists of many smaller PNP junctins, which are connected internally to generate the RF output. When you stress this transistor, some junctions can blow, reducing the power. The more junctions that blow, the less power.

I know one thing, I'd never buy any radio gear from you knowing what you do with your radios.

Bruce1807 wrote:Not only will the radio be highly inefficient as to what it is suppossed to do , the strain on the power amp will finally kill it.
a 403-470 on a 490 probably won't cause much but on a vhf the damage will occur every time you tx.
As a health & Safety issue you arecreating rf issues that are non complient within the radio

With RF issues like you mention, I've seen radios with the wrong antenna not being able to transmit DPL's properly. With such a high SWR, it "scrambled" for a lack of better terms the DPL, and no other radios would unsquelch. Switched to the proper antenna, and whammo, all radios could now hear the radio with the wrong antenna.

Hightower wrote:I know one thing, I'd never buy any radio gear from you knowing what you do with your radios.

nah, i only tested the no-antenna thing for 2 seconds on each radio, they still work perfectly, as my Moto dealer said at the last routine checkup. and i was asking about the use of different antennas because i was curious. i dont make a habit of destroying radios, and i havent made any into expensive bricks All of my radio equiptment works, and I intend to keep it that way. I guess the antenna knowledge i'm gaining is just one way to learn about radios, how they work, and how to care for them.

Not for nothing, but "gaining knowledge about radios" usually starts with reading and studying the theory about why the radios work the way they do.

Making a statement about transmitting without an antenna and then bragging abut how you "haven't turned your radios into expensive bricks" shows that you lack even a basic understanding of RF theory. It’s akin to driving your car without oil. You might get a few miles down the road without obvious damage, but the damage has been done.

In all honesty, I smell a troll here, but on the off chance you're a real guy who's simply clueless, I suggest you starting your reading here.

http://www.myradiomall.com/cgi-bin/cate ... FO_COURSES

Research on the net is a better way to gain knowledge than frying the PA in your radios. As an aside, how often do you bring your radios to the Moto dealer for a "Routine Checkup"?

N7LXI wrote: but on the off chance you're a real guy who's simply clueless

that would be me, im new to M radios. bought my first few used a couple of months ago, they were sent to the dealer immediately for routine checkup. I figure i'll send them in every 6 months or so for their routine checkups.

BTW, i wasnt bragging about "not turning it into a brick", i just heard someone use "brick" as a term for a dead radio and i thought it was a great way of describing it. thats all. Oh and also, thanks for the great link.