How low will it go?

hamsexy · Post by **hamsexy** » Wed Sep 29, 2004 7:00 am

I have a 30 watt Maxtrac on 900mhz. How low can you turn down the power to drive an amplifier?
I want to be able to use the regular mini-uhf jack on the back of the radio.

rocketman · Post by **rocketman** » Wed Sep 29, 2004 12:33 pm

My only experience with 900 Maxtracs turned down (about 1.50 watts) was with a 12 watt unit. It looked stable both in terms of a spectral analysis and operation. We used it as a repeater exciter until we got the Nucleus II up and running. I'm not sure about the 30 watt unit being as stable. I have been running a Maxtrac on the 450 band at about 1.50 watts for a while now and it seems to be holding out pretty well. It's a 25 watt model. The one thing that you will find however, is that the rig will still run warm despite running a low RF output. In terms of efficiency, at low power they are inefficient. You do have to do a spectral analysis check when running these radios at such low output, as it is possible for them to not be the cleanest spectrum wise. Their specs for spectral purity are generally rated at their intended output power.

Dave

Max-trac · Post by **Max-trac** » Wed Sep 29, 2004 1:49 pm

Do a search here. It has been discussed a lot.
The RSS will not control it out of band....
You have to set up a circuit to manualy set the drive level.

kcbooboo · Post by **kcbooboo** » Mon Oct 18, 2004 5:55 pm

A more stable solution is to buy an appropriate coaxial attenuator on eBay. Several are usually for sale all the time. Narda makes great ones that are usually good to 1 GHz or more. I have one that'll handle 50 watts and give me 30 dB of attenuation. If you get one with 10 dB of attenuation, that'll drop your power by a factor of 10, which would give you 3 watts from a 30 watt radio. You can then adjust the MaxTrac's transmitter power within the usual range and get whatever power you might need to drive your amplifier. As the radio will be stable at a legal power level, you should be good to go and not have to worry about spectral purity. Make sure you have PLENTY of air moving across the heat sink and the attenuator.

Bob M.