Here is the duty spec on the R1225 radio. I used to maintain LOTS of these in different flavors. You can have the GR 1225 desktop, a RKR 1225 rack mount housing or a GR400 wall mount housing. All of the GR1225 repeaters that I "inherited" failed eventually because they were set at high power. Easy to fix by changing out the complete PA unit. When fixed and the PA aligned and set to 25 watts MAX out of the radio, only had 1 failure after that. However, I set the fan to run continuously. In the RKR1225 chassis, fan runs on high blowing right on the PA. Radio might last longer at high power but it's still outside the duty cycle and will most likely fail at sometime. I would not try to reduce the transmit power to less than 25 watts on the high power radio because of the spurious problems others have mentioned. If you need to drive an external amp or run less power, either find the 1-10 watt radio or get a in-line attenuator, 25 watt rated at 3 or 6 db attenuation. You'd then have about 6.25 or 12.5 watts available at the output of the attenuator.
Dave NN4TT Duty Cycle: Continuous @ 25W and 1-10W 50% @ 45 / 50 W ( 5 min. on / 5 min. standby) ________________________________ From: Robert McNeill <rob...@ncbfi.org> To: Repeater-Builder@yahoogroups.com Sent: Thu, July 29, 2010 11:11:43 PM Subject: RE: [Repeater-Builder] Adjusting low power on an R1225 repeater Is there an issue running one of those at 25 watts continuous? It is a repeater. What was it’s intent if not to be used in a heavy duty cycle? 73, Robert K5ILS ________________________________ From:Repeater-Builder@ yahoogroups. com [mailto:Repeater- buil...@yahoogro ups.com] On Behalf Of Joe Sent: Thursday, July 29, 2010 9:06 PM To: Repeater-Builder@ yahoogroups. com Subject: Re: [Repeater-Builder] Adjusting low power on an R1225 repeater Thanks Eric, I though there was a caveat to turning it down, but couldn't remember why. I want to experiment with an EchoLink repeater, but I'm not sure that the R1225 UHF hi power could hold up at 25 watts continuous duty. I think I'll do some shopping as you suggest. 73 and Thanks, Joe On 7/29/2010 10:01 PM, Eric Lemmon wrote: > Joe, > > Yes, indeed! The UHF high-power version will likely either go spurious or > burn up if set that low. The only way to go with the radio you have is to > add a 6 or 10 dB power attenuator rated at no less than 25 watts, and set > your TX power at the low end. Admittedly, this is a "kluge" of the first > degree, but hey- you asked! > > Otherwise, try to get your hands on one of the 1-to-10 watt R1225 units, and > you can have a ball. I suppose you could modify your high-power R1225 into > the low-power version, but that is a lot of work, and the opportunities for > permanently damaging the mainboard are legion. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: Repeater-Builder@ yahoogroups. com > [mailto:Repeater-Builder@ yahoogroups. com] On Behalf Of Joe > Sent: Thursday, July 29, 2010 6:45 PM > To: Repeater-Builder@ yahoogroups. com > Subject: [Repeater-Builder] Adjusting low power on an R1225 repeater > > > > Hello to All, > > I want to turn the power down on my Motorola R1225 repeater to about 5 > watts. It is the high power UHF version (25-45 watts). The reason for > the low power is to drive a power amp at the output I want to achieve. > Any drawbacks to running the R1225 this low? > > 73, Joe, K1ike >
