Motorola T1500 or OEM flatpack for 1225 repeater?

[rescuecomm]

Is it worth getting a new cable harness for an unplated T1500 or just stick with the OEM mobile type plated flat pack duplexer? My GMRS group is talking about upgrading but the guys don't want to ante up $1200 for a new 4 can unit just to gain 3 db.

 

[petnrdx]

I would always recommend the real T1500.

 

[rescuecomm]

Some people have silver plated the T1500 to improve the performance.

 

[Project25_MASTR]

If you are pushing more than 30W...T1500 or a band-pass/band-reject duplexer.

 

[prcguy]

Motorola specifies the cable lengths for the T1500 for various frequency ranges and its easy to make the cables with RG-142 and silver plated PL-259s. They tune up easy and provide adequate isolation, around 85dB. A flat pack at best gets around 75dB and as mentioned, power should be limited using those.

 

[prcguy]

I see in the first post your looking at gaining 3dB by going to a different duplexer and there really is not much loss difference between a good flat pack and large 4 can, they are both in the 1 to 1.5dB loss range. The flat pack will have no band pass capability at all, limiting the placement of the repeater to a residence in the wilderness otherwise you risk interference from other radio systems. A T1500 will allow you to run 100w or more if you wish and with some reasonable band pass characteristics. One of the finest UHF duplexers ever made, the PD or Celwave or RFS 526 series is a 6 cavity with about 1dB loss and 120dB of isolation. These are all over the place in the $500 range and sometimes in the $200 range. I've never paid over $250 for one.

While were at it here why don't you dump that 1225 repeater and get a real repeater like a Quantar? I've bought several 438-470MHz 110w units off ebay in the $600 range and just a few weeks ago I got a range 3 470-490MHz 110w for $213 and it tunes up just fine on GMRS. I bet you have way more than that in a 1225 repeater with a tiny fraction of the performance.

 

[rescuecomm]

It's not my personally owned repeater, but I have an interest in seeing it get back on the air. There are 3 or 4 guys that keep the repeaters on the air and I know them on a first name basis. It is in a superior location regarding my AO and apparently doesn't have desense even using the flatpack. The repeater is currently out for repair and the T1500 is surplus off an amateur DMR repeater. Just thought since the flat pack was working okay, just leave it.

 

[prcguy]

Many repeaters have desense problems and the owners are oblivious to it unless they do very specific testing to reveal it. I had a couple of portable repeaters through here a few weeks ago using some CDM radios and flat pack duplexers and with the best tuning I could do there was still about 3dB of desense when the transmitters were on. The owners simply thought that's how repeaters work. They also had the radios programmed for about 30 watts output and they didn't have the software available to turn them down while they were here on my bench. The transmitters will fail at that power level and if turned down to 10 watts or so the desense will improve and the transmitters will live longer.

I have little patience for crappy repeaters and mobile duplexers. You can put together a very fine repeater system including duplexer for less than what people are charging for cobbled together CDM radios and a 30yr old flatpack duplexer. And the owners of these sh*tty repeaters wonder why radios on simplex work farther than through the repeater. Duhhhh.

If you have a T1500 available here is the manual that will tell you what the cable lengths are for your frequency range and I would highly recommend getting the T1500 working and replace that flatpack. Not sure what else you have in your repeater system but this would allow you to run the 1225s at lower power to then feed an amplifier and run full legal power or more with the radios running cooler. Hopefully your T1500 is a pass reject type and not a pass only.

It's not my personally owned repeater, but I have an interest in seeing it get back on the air. There are 3 or 4 guys that keep the repeaters on the air and I know them on a first name basis. It is in a superior location regarding my AO and apparently doesn't have desense even using the flatpack. The repeater is currently out for repair and the T1500 is surplus off an amateur DMR repeater. Just thought since the flat pack was working okay, just leave it.

 

[rescuecomm]

That's why I was asking. Okay on replacing the flatpack. I assumed that the GR1225 was bought as a package deal by the guy who brought it here. The OPs that used it seem to have WT's, so the TX power can be whatever.

 

[speedway_navigator]

There is a tech note on cleaning and reburbing T1500s on the cactus ham network site.

Cactus Intertie System

www.cactus-intertie.org

The site won't load for me now, it worked earlier this week.

 

[prcguy]

I visited the Dayton Hamstervention this year and between a friend and I we scored four Motorola T1500s in nice shape for $50 each.

 

[petnrdx]

That is a VERY good price for VERY good duplexers. Wish I could find them in that price range.