Re: [Repeater-Builder] Radio for repeater use
Mastr IIs are pretty good radios in repeater service. Is yours a converted mobile or a base station with the big heatsink? G7s have been problematic for repeater service in New Englands climate, not sure about yours. Not sure about the power increase on warmup. If you have a spectrum analyser, does it go spurious? I have seen that, usually cured by a by the book alignment. I'd sooner look at the duplexer, RX preamp (if used), cables, and the aforementioned antenna, before swapping out the radio. There are lots of good alternatives for VHF repeater radios, depends what you can find, and your budget. I much prefer commercial equipment over ham rigs. Good Luck de W1EL Eric Lowell Eastern Maine Electronics Inc. 48 Loon Road Wesley ME 04686 eme@starband.net www.satnetmaine.com --- On Sun, 10/4/09, W3ML w...@arrl.net wrote: From: W3ML w...@arrl.net Subject: [Repeater-Builder] Radio for repeater use To: Repeater-Builder@yahoogroups.com Date: Sunday, October 4, 2009, 2:24 PM Hi All, I am looking at the changing radios on our repeater because of the problems we are having. We are using a GE Mastr II into a 6 can duplexer and up via 1/2 hardline to a G7-144. However, we can not raise the power above 10 watts before de-sense sets in. Also the radio will climb in power level as it gets hot. I set it at 5 watts out and by the end of a half hour net it is up to 12 watts out. In my opinion this is not right. What radio would be good for a 2 meter repeater. Thanks and 73 John, W3ML
Re: [Repeater-Builder] Radio for repeater use
John--- Just read today's emails---seems to me that we can make the assumption that your repeater system did at one time work to everybody's satisfaction and then went bad with a desense problem. If this is the case. we are looking for something that has degraded from being acceptable--its probably not the time to start redesigning and replacing the system from one end to the other--but to fix the problem -especially as you are under pressure to perform a quick fix. Now, you mention that your system includes a G7-144 (Hustler) antenna and I read in your responses, several comments as to the Hustler antenna not being very good and in fact being the cause of many problems. This is indeed the case when corrosion sets in-The antenna can switch from being a fine performer to a source of totally disabling desense. I say this from experience with the antenna---I've been there and VSWR readings remained normal. My problem was that corrosion between the elements of the G7 antenna resulted in rectification of the transmit energy and generation of wideband noise around the transmit frequency with sufficient noise energy at the receive frequency (which went back down the feedline, through the duplexer and straight into the receiver) to swamp all but the strongest local users. How do you determine if this sort of thing is responsible for your trouble? Replace the antenna with one known to be good or if this can't be easily done-do some iso T testing. Iso T testing can be a bit involved for a beginner and some auxiliary test gear is required which may not be availableyou can read about this in the RB archives. In your case, a simple antenna change may be easierjust about any antenna will do from an AX-50 onjust be sure that the antenna you try is in good shape and the repeater won't care. If I'm on the right track, ask questions---and yes, the G7 antenna can be rebuilt to better than new---been there and done that ---and am in fact still using it now. Scott, N6NXI - Original Message - From: W3ML To: Repeater-Builder@yahoogroups.com Sent: Sunday, October 04, 2009 10:24 AM Subject: [Repeater-Builder] Radio for repeater use Hi All, I am looking at the changing radios on our repeater because of the problems we are having. We are using a GE Mastr II into a 6 can duplexer and up via 1/2 hardline to a G7-144. However, we can not raise the power above 10 watts before de-sense sets in. Also the radio will climb in power level as it gets hot. I set it at 5 watts out and by the end of a half hour net it is up to 12 watts out. In my opinion this is not right. What radio would be good for a 2 meter repeater. Thanks and 73 John, W3ML