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amplifier help
Posted: Sun Apr 23, 2006 5:09 am
by gts1007
I have a TLE1713A power amplifier from an old micor that the transmitter is fried.
Can I use this on a CDM1250 RICK set if I turn the TX power on the Transmit radio down to 1 watt ?????
Thanks
Posted: Sun Apr 23, 2006 1:15 pm
by Will
The Micor PA deck requires external power control circuit to keep from burning up the PA due to overdrive.
The CDM wil NOT work at the one watt level, it ISNOT designed to run at one watt. The get squerilly.
Most do not recomend this setup.
If you can find a LPI GM series radio that IS designed for 1 to 4 watts power out put. You still need some power control for the Micor PA.
Posted: Tue May 09, 2006 3:55 am
by AEC
If you are using a high band Micor, the drive needed for full output is only 400 mW, and this is for the TLD5321A on 132-150.8 Mhz.
I would not recommend driving the Micor P.A with anything more than 400 mW as you will run the P.A driver stages into overload and probably burn out the first input stage if you are runnning the 110 watt P.A, either UHF or VHF, the drive requirements are pretty much the same.
And you will need to use power control to regulate the output level, otherwise you run the risk of destroying the P.A deck if it overheats and goes into thermal overload, where you will see the P.A current shoot up with no increase in output power.....your P.A will be dead soon afterwards!
Micor P.A decks are pretty bullet proof for SWR overloads, but they do NOT like to operate when their P.A current draw gets into the red zone, then you can watch the ceramic caps on the transistors pop off and you'll have let the smoke out.
Posted: Sat May 20, 2006 7:50 am
by Bruce1807
Just run 0-9.6V on the control line but with no feed back circuits you run a small risk.
Keep it at about 5 volts and youll get plenty of power.
As for real bullet proof they are far from it.
I had a site not transmitting. Went in the site, did a check PA not transmitting. Took the cover off and what a mess. I thought a transistor must have exploded by the amount of lead.
Closser inspection led to a big dent in the heatsink. I then looked at the cover and saw a hole. Thinking what the @#&* l looked at the site door and saw a little beam of light.
Not sure of the caliber but all doors on our sites were at least .22 and shotgun proof. Was there at the testing and even solids bounced off.
I measured the hole on the door and as it was small so I'm going for a .223 any way replaced the PA, siliconed the hole and left the scene in case the wierdos returned and tried again.
Posted: Sat May 20, 2006 12:58 pm
by bernie
My two bits worth:
Why not repair the Micor?
The power control line, the yellow wire usuially has about 7V on it when keyed. The input power level is approx 1 W.
If you wish to use this amplifier with out the Micor chassis, connections are the same as the bench set up for repair.
Caution! too much drive will fry the input transistor.
The set up that I used had a power attenuator from a UHF Mocom 70 Consollette.
I used a second power supply for the control voltage, perhaps you could use a zener diode to set the control voltage.
The drive line can be connected to the A+ for testing.
The amplifier can be over driven causing spurs.
If it is necessary to have the control line at 14V for full output is a symptom of a bad pre driver transistor.
Be very careful with the output of the amplifier. This amp will easilly exceed 100W into a dummy load.
The Micor station has an output circulator assembly, which has loss, the station is rated at 70W.
Operating the amplifier with this output level into a bad load will cause damage.
If you use an external circulator, be sure to follow it with a harmonic filter.
A cavity duplexer would also work.
Inspect the chip caps. Look at tthe solder connection on the terminals of the cap.
Note that a special 2% silver bearing solder is required when working with chip components.