524 not transmitting

[mgtrooper]

I hooked up my 524 today and could receive but could not transmit. My buddy has a 524 to help test it out. When I key the mike there is no windup in the radio. We switched mikes and no change. We switched radios and no change. Any ideas?
http://i1233.photobucket.com/albums/ff3 ... G_0714.jpg


I just wanted to post a photo of my M38A1 with the 524. I am going to put together a mount for the 6707 before I transmit any more. I have heard enough counsel that these radios work better communicating via transmiting radios wave than smoke signals.

Steve

[moose53]

a couple quick things to check...

not having seen your radio, this may sound dumb, but here goes,

first, is the radio complete? the majority of them were demilled by the removal of three or four key parts.

next,is there power to the radio mount?

next, is the jumper in the power connector on your radio mount set correctly? Radio won't power up if it's wrong...

next, is the plug cover on the X-connector in place? You won't get audio without it. Theres circuitry in the little cover.

next, is the internal X-mode switch set to off? The majority came out set to x-mode so they would work with the KY-57 scrambler. It needs to be off for normal mode.

also check your squelch settings, use the old style setting for testing....

just random things it could be, short of needing repairs... I bought a non-working R-422 and the x-mode switch setting was all that was wrong with it!

good luck,

Jim

[mgtrooper]

Jim,

Thanks for you advice. I have some questions but first:

I do not see any obvious parts missing. no covers missing etc.
The radio will receive and turn on so I do have power to the mount.
Where should the jumper in the power connector be set, and is that the little box on the mount where the radio plugs in?
The plug is on the X-connector.
How do I get to the internal X-mode switch and how do I tell if it is set ot off.

Thanks for your help.

Steve

[moose53]

Jim,

Thanks for you advice. I have some questions but first:

I do not see any obvious parts missing. no covers missing etc.
The radio will receive and turn on so I do have power to the mount.
Where should the jumper in the power connector be set, and is that the little box on the mount where the radio plugs in?
The plug is on the X-connector.
How do I get to the internal X-mode switch and how do I tell if it is set ot off.

Thanks for your help.

Steve

if it turns on and receives then disregard the power jumpers they are fine. yes the jumper is in the box where the radio plugs in.

the internal x-mode switch is in the bottom of the radio.
take the bottom cover off
set the radio on its handles, face down, power plug to your right.
locate the A-4000 module, on the lower right side of the radio.
loosen the two captive screws on the A4000 board and pull it down toward you. It is hinged for easy access.
locate the switch on the underside of the A4000 board
ensure it is set to "normal", not "x-mode"
fold A4000 back in place
tighten two captive screws on the A4000 board
replace bottom cover, you're done!

The parts usually removed to demill the radio are the A1000 freq synth module, the Final RF tube, the heat sink for the tube, and the capacitor which went from the tube mount to the chassis. While inside the radio also make sure none of the little wire jumpers that connect the modules have gotten disconnected or gone missing...


Jim

[mgtrooper]

Jim

I did access the A-4000 module and set it to normal from X-mode. That was a brilliant piece of advice. I keyed the mike and the radio came to life. My buddy about 9 miles away could not hear me but I have no ground on my antenna. I could however barely hear him faintly behind static but my call light would not come on when he transmitted to me. His call light would come on when I keyed but he did not receive a voice transmission. I am much closer tonight to having a working 524. Thank you.

[moose53]

you're very welcome, glad its working out...

Jim

[salt6]

Check your matching unit and make sure it is tuning to the freq you're on.

[mgtrooper]

roger, We are testing on 50/50

Steve

[rickf]

Do you hear your antenna matching unit changing while you are switching frequency's? If not you will have to set the antenna match manually.

Rick

[mgtrooper]

Rick

No. I do not hear it changing. As a matter of fact. If i just have the antenna coaxle pluged in but not the power lead to the antenna base, my radio will "winde up". If I do have the power lead pluged in it will not winde up.

In addition, when I turn on the radio after it has sat for a while and I key the mike I get no winde up. I then turn it off and back on, key the mike and I get winde up. Is there a breaker bein triped by the base? Is this a ground issue?

Steve

[Rainman]

Hey MGT,
What's the rundown of your history with this RT? Just get it, been in storage, worked when you first got it, first one you've ever owned? When this all started I got the impression this problem started suddenly to a serviceable radio. I would have never thought about mode switches because it's not easy to do that by accident. Great call Moose.

Manual tune will work fine but you should consider testing out the entire system before you ever start transmitting into even a dummy load. These old rigs were ridden hard and long and not always well maintained. MX6707's are one of the most plagued parts of the system. Half of the ones I've seen don't work any longer and lots of that is from water damage and internal shorts. A bad one will kill your radio in the blink of an eye. Simple little things like not having everything grounded when you key the mic, or a power surge by starting the engine with the radio on can be catastrophic. I learned long ago... there is smoke built into every piece of electronic equipment, it takes a real genius to get it to come out.
Rainman

[rickf]

Whatever you do NEVER key the mike without an antenna or dummy. That will let the magic smoke out.

Rick

[mgtrooper]

Radio history:

It is a recent acquisition from a friend who got it at auction years ago. He clamed that it worked. Most likely he got power to it, it powered up but I am sure he could not test transmission as he had know one to talk to. When I opened it up at Ricks suggestion to switch from X to normal, I did see a 3/92 sticker inside. I know nothing about these radios so the excitement of getting one running may have prompted me to put the cart before the horse. I am sure I have keyed the mike without the mast on but I have not made the smoke appear. Needless to say, I will not do that again. My gut feeling is that if I have not wrecked it yet, I have a working radio but I have to get the 6707 mounted and grounded. Make sure my 6707 is tuned to the frequency I am attempting to transmit on. I do not have all the mounting parts needed for the 6707 mount so I think I will go AB-15 for now. I do have an AB-15 and antenna but I have to find the adapter for the coaxial to the base.

I have to say I really appreciate both of you commenting here. It is extreamly helpful. Thank you for you willingness to help and your interest.

Steve

[snock]

It sounds to me like your transmitter is working properly but you have no modulation. You didn't say whether you were using new or old squelch. New squelch sends a 150Hz tone along with your audio to unsquelch the receiver and old squelch simply uses received signal strength to control the squelch. Try it again using new squelch and see if his call light comes on. If it comes on only with old squelch then you are transmitting an unmodulated carrier. If it comes on with new squelch then at least the 150Hz tone is making it through. This will help narrow it down a bit.

As far as using an AB-15 on an RT I would not recommend it. The antenna impedance needs to match the radio's impedance otherwise you risk burning out your final output amplifier. There is a specific length the whip will be resonant at for a given frequency and since you can't change the length of the whip in a practical fashion the MX-6707 makes it look longer or shorter to the radio using capacitors and coils if that makes sense. If you have an R-442 then use the AB-15 with it.

[Rainman]

Hey MGT,
Thanks for the rundown. It's possible to use an AB15, but like Snock mentioned, you need to have it tuned (adjust the length) to the freq you are transmitting on or you may see that smoke. Just like in the old CB days reflected power is a bad thing known as SWR. The tuning cable from the RT to the MX6707 is the CX-4722A/VRC and needs to be connected to get the auto tuner in the 6707 to function. That's in addition to the CG-17738/U antenna cable. Grounding the antenna can give you up to 2X the effective function of the antenna. Not that your getting into base station operations, but an RC-292 antenna stationary antenna will get your transmit way up into the 25 mile distances. If you have a buddy into amateur radio, they may have all the testing equipment and connectors you'll need to verify the integrity of your antenna system. In effect you can have 25 watts of transmit power with very little leaving the untuned antenna and feeding back into you radio. Wheres Tony Banks and why isn't he chiming in on this thread yet?
Rainman