modifying cdm1250

jmr3865 · Post by **jmr3865** » Sat Mar 25, 2006 5:51 pm

Is there anyway to modify a cdm1250 from 25 watts to 50 watts or even 100 watts? thanks in advanced

RFguy · Post by **RFguy** » Sat Mar 25, 2006 7:26 pm

External amplifier?

jmr3865 · Post by **jmr3865** » Sat Mar 25, 2006 7:30 pm

Where can I purchase one of those? do they go up to 100 watts, maybe more?

thebigphish · Post by **thebigphish** » Sat Mar 25, 2006 7:44 pm

you are really trying to get that elusive 100 watts aren't ya!

google UHF external amplifier - and some Herley & Rhode-Schwartz units will come up...

jmr3865 · Post by **jmr3865** » Sat Mar 25, 2006 7:45 pm

need vhf

nmfire10 · Post by **nmfire10** » Sun Mar 26, 2006 4:56 am

What are you trying to accomplish? I would be willing to bet that whatever it is will gain nothing by sticking a 100w mobile amplifier on your radio.

jim · Post by **jim** » Sun Mar 26, 2006 10:02 am

Going from 25W to 100W usually does nothing except when operating simplex over extreme distances where you can barely be heard at all. And I mean barely.

A higher efficiency antenna usually does the trick.

Everyone thinks that 100W is needed when the truth of is that 25W will almost all the time work. If you do the math, there is very little gain from this increase.

kb0nly · Post by **kb0nly** » Sun Mar 26, 2006 10:09 am

I can tell you one thing, 25w wouldn't do diddly to get into some of the repeaters around here that i can get into with 75w, regardless of antenna.

Lots of hills and a ridge to the West inbetween me and the repeaters i regularly use.

HLA · Post by **HLA** » Sun Mar 26, 2006 11:26 am

i'd like to know also why he's stuck on 100watts and what he wants to do with it? first do you have a license for the frequency you intend to use it on and is for that much power? do you already have a cdm1250? most vhf cdm1250's are 45 watters, that along with a high gain antennae will be equivalent to more than 100watts. where are you located, what kind of obsticles are you trying to get thru with that?

nmfire10 · Post by **nmfire10** » Sun Mar 26, 2006 12:37 pm

I think he just hasn't come to accept yet that in most cases, power does not equal distance. Before I became the radio nerd that I am now (most education from this site), I was of the same mindset... crank up the power to crank up the distance. If only it was actually that simple!!

jmr3865 · Post by **jmr3865** » Sun Mar 26, 2006 12:39 pm

I understand that it doesnt mean distance, but I can understand somebody on a 110 watt radio better than another 50 watt radio. It's being able to understand. thanks for your help.

HLA · Post by **HLA** » Sun Mar 26, 2006 10:09 pm

do you also realize that if you are using a repeater that whoever is hearing you is actually hearing what the repeater is putting out, not your radio.

jim · Post by **jim** » Sun Mar 26, 2006 10:13 pm

If this is a repeated public safety system, the system administrator needs to realize that there is inadequate coverage and should seriously consider additional receivers and a comparator.

thebigphish · Post by **thebigphish** » Sun Mar 26, 2006 11:21 pm

jmr3865 wrote:I understand that it doesnt mean distance, but I can understand somebody on a 110 watt radio better than another 50 watt radio. It's being able to understand. thanks for your help.

We just put those dual head / dual band kenwoods that we PM'ed about in our trucks last month...today we went simplex from Hartford, CT to Otis, MA at 50watts. That's 50 miles as the crow flies. And its not an out-west 50 miles, it's a pretty hilly 50. A properly tuned and aligned RF deck, adequate clean power, an appropriate antenna, good grounds and a solid install WILL outperform doing some slop work, on a crap deck, in a rush, with twice the power. Power is not the end-all answer.

Tune the hell out of a 40 / 50 watt deck and you will get VERY VERY similar performance.