Boosting output on a CDM1250
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jclendenen158
- Posts: 40
- Joined: Fri Jun 29, 2007 2:22 pm
- What radios do you own?: XTL2500, XTS5000
Boosting output on a CDM1250
What would be the best antenna to boost the signal strength on a 45W CDM1250.
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Tom in D.C.
- Posts: 3859
- Joined: Tue Sep 04, 2001 4:00 pm
- What radios do you own?: Progreso soup can with CRT
Re: Boosting output on a CDM1250
To provide an intelligent answer we need to know:
1. What band the radio operates on?
2. If you're running the radio in a fixed or mobile station?
3. If it's fixed how high can you put the antenna?
4. If it's fixed how long the feedline would have to be?
And anything else you can think of that would help.
1. What band the radio operates on?
2. If you're running the radio in a fixed or mobile station?
3. If it's fixed how high can you put the antenna?
4. If it's fixed how long the feedline would have to be?
And anything else you can think of that would help.
Tom in D.C.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
In 1920, the U.S. Post Office Department ruled
that children may not be sent by parcel post.
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jclendenen158
- Posts: 40
- Joined: Fri Jun 29, 2007 2:22 pm
- What radios do you own?: XTL2500, XTS5000
Re: Boosting output on a CDM1250
The band is VHF High - 136-174MHzTom in D.C. wrote:To provide an intelligent answer we need to know:
1. What band the radio operates on?
2. If you're running the radio in a fixed or mobile station?
3. If it's fixed how high can you put the antenna?
4. If it's fixed how long the feedline would have to be?
And anything else you can think of that would help.
It is a mobile install.
Primary operating frequecy range is from 150-160MHz.
Re: Boosting output on a CDM1250
A 19" 1/4 wave whip provides no gain. It radiates in a nice donut shaped pattern. 45 watts in = 45 watts out.
Every 3dB of gain doubles your effective radiated power. However it also squishes your radiation pattern to do that. It focuses more power straight out as opposed to up. So if you get a 3dB gain antenna, 45 watts in = 90 watts out. These are about 52" high with a base coil. I've never seen anything beyond 3dB gain for VHF. I just checked antenex, comtelco, and Larsen. 3dB is the most you will get.
And honestly, it isn't going to make that much of a difference. some weak areas might sound a little better but thats it. Height of the base station is the big thing.
Every 3dB of gain doubles your effective radiated power. However it also squishes your radiation pattern to do that. It focuses more power straight out as opposed to up. So if you get a 3dB gain antenna, 45 watts in = 90 watts out. These are about 52" high with a base coil. I've never seen anything beyond 3dB gain for VHF. I just checked antenex, comtelco, and Larsen. 3dB is the most you will get.
And honestly, it isn't going to make that much of a difference. some weak areas might sound a little better but thats it. Height of the base station is the big thing.
"I'll eat you like a plate of bacon and eggs in the morning. "
- Some loser on rr.com
eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"
- Some loser on rr.com
eBay at it's finest:
Me: "What exactly is a 900Mhz UHF CB?"
Them: "A very nice CB at 900Mhz speed!"
Re: Boosting output on a CDM1250
The CDM Series mobiles actually have a Pre-Amp installed in them, which makes them generically recieve so well, so an antenna with some decent gain should provide for a nice signal - but as nmfire10 stated, not much more than 3db exists. I've seen some hammy-grade antennas (ie comet, diamond, etc) claim up to 5/6 db, but I wouldn't recommend using those.