Whats up with this Maxtrac?

[Ph0t0gr4ph3r]

I picked this up for $10 (along with a Maratrac) the other week and I finally got to power it up and this is what happens when I key it up:

It just makes that weird buzzing noise and a clicking sound no matter which channels selected. Is it a problem with the PLL not locking? For now I just have it running off of some random 12v transformer that i found (not sure if its supplying enough current) so could it also be an issue with power?

 

[rescue161]

Not enough current from your power supply. Is this an 800 MHz radio that is programmed for a trunking system? Do you have an antenna connected? What is the model number?

 

[R8000]

Three potential problems I see here :
1. The radio is 30 years old and just tired and had enough.
2. Your power supply isn't big enough.
3. You are getting RF back into the radio or power supply.

 

[ten13]

Process of elimination: first, deal with any power issues, like an insufficient power supply.

 

[RBMTS]

I also agree that the problem appears to be a insufficient power issue. What is the model number of that Maxtrac? That looks like it could be one of the old 800Mhz Type I trunking radios. Perhaps it is doing that because of not having a system to attach to. Most of them "bonked" as I remember but who knows how that radio is setup.

 

[rescue161]

On the LTR Maxtracs, even on a system that is no longer operational or if the radio is out of range, they will still attempt to find a channel several times before giving the bonk. That is why I asked.

 

[900mhz]

What is the model number of this radio?

 

[Ph0t0gr4ph3r]

Not enough current from your power supply. Is this an 800 MHz radio that is programmed for a trunking system? Do you have an antenna connected? What is the model number?

The power supply was what turned out to be the main problem. Now I finally have on a PS that's supplying about 14v at a much higher current, but putting it on an rtl-sdr (as a poor man's spectrum analyzer) it seems like there's definitely some bigger problems

This is what happens when I key it up:

(Also Its worth it to note that I'm testing it in a metal shed that's basically a faraday cage, and keying it up into a dummy load that barely radiates)

I've heard that the main reference oscillator can die but I'm not sure if that's whats going on here, since I haven't been able to find any examples of what the radio does when that happens

Is it just a really messed up radio? As much as I'd like to get it working I definitely dont wanna put too much effort into it

Also this is a 449-470MHz radio (at least thats what the RF board says) Im not too sure about the exact model since it's missing the sticker that has all that info on it, but afaik it's not trunked

 

[Ph0t0gr4ph3r]

I also agree that the problem appears to be a insufficient power issue. What is the model number of that Maxtrac? That looks like it could be one of the old 800Mhz Type I trunking radios. Perhaps it is doing that because of not having a system to attach to. Most of them "bonked" as I remember but who knows how that radio is setup.

The RF board says it's 449-470MHz (its missing the model number sticker, but from info I found online it's an M100)

I finally got it on a decent power supply, but unfortunately it seems like it has some bigger issues. See the video I attached in my reply above

 

[kruser]

Is the new power supply regulated and what is the output current rating?
It still looks like a possible power supply problem.

 

[jhooten]

Overloading the front end of the dongle?

 

[WA0CBW]

Well....
Even "good" dummy loads radiate more than you might think. My vote is for overloading the dongle as well.

 

[Ph0t0gr4ph3r]

Is the new power supply regulated and what is the output current rating?
It still looks like a possible power supply problem.

It turns out my ebay-special "25A" power supply was lying to me.... hooking it up to the 12v output of a computer PSU finally got it to work, RX on 463.375, TX on 468.375. Now I just gotta find a proper PSU and a rib cable

Appreciate the help from everyone

 

[jhooten]

Maxtrac RIB to radio cables are super easy to make.

http://www.batlabs.com/images/maxpin.gif