Batboard

OK, so I am at the whim of the Moto gods. I friend had given me a GR1225 UHF repeater ( said friend owns a radio shop) and said it "sort of works, but you can always use the parts". RX is fine, it transmits from the panel mic fine, but when retransmitting it only sends for a fraction of an instant and then drops. The drop is so fast that you can't hear it on the portable in your hand, but another radio tuned to the frequency will pick it up. It works just fine as a base station, so the transmitter is good. The finals may be bad, but I lack the necessary equipment to test it.

I don't believe that the supplied Zetron ZR-310 controller is the issue, as I have removed it and the repeater still does the same thing. I have noticed that when programming over the air, I am unable to hear confirmation/ error tones from the controller, so it may have issues as well. It does respond appropriately to knockdown setup codes and such. I'm thinking maybe no audio is getting in to the transmit side, maybe a bad COR or line voltage? I dunno. It hears great, it talks great when you plug a mic in.

Does anyone have any thoughts on this issue?

An easy way to check if its a controller issue is to remove the controller cabling read and change the codeplug to internal controller instead of the external Zetron.
Doug

Unfortunately, at this time I have neither the RSS or the RIB and cables for this machine. I was attempting to see if I could get it operational before I added the expense of the RSS, et al. Any other thoughts?

PM sent

turtle9832 wrote:PM sent

Curious what was in that PM... That sort of thing doesn't help the rest of us learn.

Was the repeater TOT set to 1 second?

Is it really a R1225 or just a couple of Radius radios in the box.

When the R1225 is set for external so called controller it may not send repeat audio due to programming. So: step 1 read the radio and check the accessory potions settings.

d119,

I was trying to help him with software issues, get him to read it, then look the codeplug over. I tried to point him to communications.support (but it didn't work out for him)

I was thinking what Will was thinking.

I didn't think of the tot set to 1 sec.

No disrespect to the house here, just wanted to discuss his software concerns and cables in the back.

If his M shop friend cant help him with cables, I offered to send mine to him to get him going.

I kinda figured that was the case after I commented - no worries & good work!

he's halfway home with regards to being able to read the radio. I told him to read the radio and report back to the thread.

Mike

Yep,
at this point I'm waiting for my cables to arrive with bated breath. I don't believe that the TOT is set for 1 second; although that may explain why there is a brief moment of clarity, but does not explain why it still transmits very weakly.

Yes, it is a real honest to God R1225 transceiver; I would have mentioned if it were a couple of GM300's crammed in there. Thanks to everyone for the suggestions, i can't wait for my hardware to show up so I can dig into this thing.

Lastly, my apologies for the delayed response, I've been sort of busy lately. My boss went on vacation for two weeks which left me in the position of an acting facility administrator. Combine that with my FD stuff and (finally) getting my EMT license over the last week and you get one busy, tuckered out dude.

No one has come right out and suggested to put a watt meter right on the output of the transmitter port.

Could be a transmitter problem or a duplexor issue. Last place to look is a bad piece of coax cable.

On the Spectra radios, I have found the mini RF connector center pin has been damaged on some radios and does not make a good connection. You can prove this by pushing the cable to one side or another with the locking ring not real tight. There is a way to attempt to fix this, but not for the rookie to attempt.

Jim

The wattmeter is a good idea. I'm lacking one however, and also the service manual. On the R1225 is the transmit connector on the forward or the rear end? I'm completely ghetto on this job; I need so much test equipment that it's scary.

Thanks for all of the suggestions, everyone. I really appreciate it. I know I probably should have spent the big bucks on a genuine /\/\ cable for it, but I ordered one of those Asian cables. I'm basically trying not to tie too much money into this project since I got it for free. It would be stellar if I can get it on the air though, as I have about twenty Vertex VX-800U's that were also donated.

The Transmitter coax cable connector is on the back of the R1225 chassis along with the power and 16 pin ACCY connectors.

The receiver antenna connector is on the front, along with the 'control head' connector.

Just an update for those interested. . . . Still waiting on my cables to arrive. I can't wait to dive into the program and see what's what. Will report back after investigating.

Ok gang, here is all the news that's fit to print. . . .

Firstly, I would like to thank everyone that has chimed in with suggestions. They have all been duly noted ( and most attempted.)
I appreciate all of the assistance that everyone has rendered up to this point.

Now, for the nitty gritty. Today my cable arrived in the mail. After playing around with a couple of different USB to RS-232 converters, I finally got the damned thing to work.

Success! I can now read my repeater!

I tried plugging the cable into the "PROGRAM" jack on the ZR-310 Controller, but it wouldn't even acknowledge its existence. That thing may be wonky because it decodes the PL just fine but didn't seem to do much else. So, I just unplugged it and went my merry way configuring the rig to use the internal controller.Part of my problem was that the hang time was indeed set to one second. That made a difference as I can now hear the re-transmitted audio from a second portable, and the fact that the transmitting portable hears the repeater when I let off of the PTT key. so, we're good there.

Sadly, it appears as though PA may be kaput, as I can only hear the repeater from a distance of 10 yards, give or take a few feet. This has been tested both through the cans and with the transmitting antenna attached directly to the mini UHF socket on the back of the R1225 chassis. It looks like I need a new radio. If I can, I'll try to borrow a wattmeter and see what it reads, but if the field strength tests failed as miserably as they did, I'm pretty sure that the meter will be a moot point. It seems like it hears just fine, so maybe I can homebrew the receiver into something. I dunno.

On the positive side of things, I'm only out $12.25 for the programming cable and the repeater was free. I now have the capability to program Radius 1225 radios, so there's that.
I happen to know of another GR1225 located at my club's 2M repeater site that has been " abandoned in place" with not even an antenna hooked up to it. I may have to talk to a few people and see if I can make it disappear.

If anyone has any thoughts or suggestions, feel free to throw them out there. Also, if anyone has a spare UHF R1225 chassis laying around that they would like to sell (for cheap) or trade for, I'd be interested getting in touch. MODERATORS, If the last sentence was out of line, please advise and I will strike it from the record.

So, that's all I have for the group for now. I again wish to thank everyone for their thoughts and suggestions, this was my first foray into /\/\ programming and it wasn't all that bad. Just bad equipment.

(Now , to write a custom codeplug for the two new TK-2312's that the Fire Department just sent me. . . . . . )

PA Failures on GR1225's are common. The PA may still be available as it's own item from Motorola...

Dollars to doughnuts its the transistor... consists of replacing 4 caps and the transistor IIRC... beyond common with the 1225 series...

Well, I can always dive into the thing and rip apart. Does the service manual contain things like parts lists? Specifically the values of the capacitors and the transistor information? I'll have to see if I can get my hands on one regardless. It will help with the dissection. I have torn aprt ( and re-assembled ) a MaxTrac/ Radius so it shoudln't be too much different from that ( I hope.)

I'm not sure from reading these posts if you actually ever read THE RADIO with the RSS. If the RADIO has a control head you read and write to the radio through the mike jack it.

If the radio doesn't have a control head (which it sounds like yours does) you can remove the small front cover, mash on the volume control board from a GM300, an M120 or 130 (NOT A MAXTRAC) and communicate with the radio. If you don't have ANY type of front cover you will need to connect pins 7 and 8 with one of those little push on jumpers like from an ancient computer to power up the unit.

All that notwithstanding (the biggest word that I know) the R1225 is a GM300 based product. The PA is very similar but mounted in a very serious heatsink and the logic and RF boards are redesigned GM300 items. I know that because I was told so by the engineer that designed this product and for that matter, the whole MINITRAC series; Maxtrac 50 through the R1225.

Actually the R1225 IS very different than the GM300 series.

The high, 40 watt, PA has problems overheating even with the bigger heatsink, and the current sense resistor gets fried also. Two big problems in original assembly of the PA board in the heatsink. /\/\ used too much of a poor quality heatsink compound which dried out. The part of the heatsink where the transistor mounts is not flat, just ruff casting, so the heatsink is not able to transfer heat away from the poor transistor.

I mill the transistor mounting surfaces in the PA heatsink casting flat and use Artic Silver heatsink compound.
Some times I can rebuild them. It may be as simple as one of the solder joints has be come crystallized.

I have the manual. And I have made some mods on the PA over the years.

And I have a programming/test cable just for headless R1225 repeaters.

TWEMARS wrote:I'm not sure from reading these posts if you actually ever read THE RADIO with the RSS. If the RADIO has a control head you read and write to the radio through the mike jack it.

Read, and wrote, quite a few times. You may have missed where I stated that I changed the program from the external to the internal controller and adjusted the hang time.
Since then, I've stripped nearly everything out of the repeater chassis except for the RF deck. I needed the power supply for programming some other /\/\ stuff. One day I might put it all back together.