Bauer Power

[Rick K5IAR]

I can't find any info on this, so maybe one of the more experienced Bauer 707 technicians can advise me.  Does the power control motor assembly have a limiting mechanism to prevent burning up the motor if/when the 300 ohm/100 watt rheostat reaches it's limit in either direction?  The rheostat in mine had been crudely replaced by punching a hole in the front of the cabinet and wiring around it, so while investigating that I tested to see if the motor had limit switches.  The motor does stop at each end, however, I'm not sure if it's due to an internal limit switch or the fact that it reached the end and simply can't turn. 

I moved the patch job from the front of the cabinet into the motor assembly and all is right with the world.  I just don't want to burn anything up or strip the gears in the gearbox.  Anyone familiar with this issue?

Thanks,
Rick/K5IAR

[flintstone mop]

I'm always trying to short cut things and this may not be the way you are working with the Bauer. The motor driven power control was for AC power variations and for making FCC license power, especially if there was a loss or some anomally in the antenna system that the original design allowed for a few more watts to meet FCC license.
If this is a 1kw box, can you select taps for the 250 or 500 watt level and forget the power control circuitry? I can understand that some folks want to return the equipment back to the original design, but to get it operational and on the air I would skip that part of the TX and turn the motor for full juice to the final.

Fred

[Rick K5IAR]

Thanks Fred for the information and suggestions.  The control seems to work properly since I replaced the defective rheostat, I was just curious about the limit switches.  I started out gung-ho to put this box back to 100% original condition.  However, I have run across too many items that would be unreasonable to restore to that state, so I am trying to get her close now.  I sometimes get wrapped up in details and lose sight of the big picture. Thanks again.

Rick

[flintstone mop]

Yea OK Rick,
broadcast time is money and sometimes, fumbling fingers at 2:00AM in the morning will destroy the best of designs. The Bauer should be a nice audio signal on 160M or 80 if you want to multiband.

fred

[Rick K5IAR]

I agree, Fred.  I have all the respect in the world for the engineers who keep these things on the air.  I doubt how it looks or whether or not it's a direct replacement part means very little when the clock is ticking and your off the air.

I am going to set it up on 75 meters for now.  I may multi band it later, but I doubt it.  I have the old GE 250 watt box on 160 and BC-610's for the othe bands, so I hope to set this one up on 75/80 and leave it.

Thanks again for the info and comments.

Rick

[VE7 Kilohertz]

HI Rick,

I think you are referring to the screen supply reohstat?? Which is what controls (fine tunes) the output power. The gross output power change is through either a center tap on the high V xmfr or a dropping R depending on the vintage and low power rating of your TX.  Is it the about 4" dia pot right behind the front panel on the left (from the front) side? I don't think it has limit switches. You need to listen for the motor to stop. I have one in my shack and it works great. Sounds wonderful. Makes a nice small(ish) 1KW TX for AM.

Good luck and look forward to hearing it this fall when I return to 75M AM. Too many summer projects for radio right now.

Cheers

Paul
VE7 kilohertz