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• We had one at Looking Glass Studios back in the late 90's. sat right below the 175. People seemed to like it......

• Hi Chris:

  A bit of a factual correction on the LA-2A. Bill Putnam's equipment company, which became UREI, bought Teletronix.

  The LA-2A was invented and patented by Teletronix founder Jim Lawrence, who received a patent for the use of the electro-luminescent panel as the gain-control element. Lawrence wrote an excellent article detailing the theory and development of the LA-2A for the SMPTE Journal.

  The ad above shows the original Teletronix version, before Bill Putnam bought that company.

  Mix Mag did a decent write-up on the LA-2A history here:
  http://mixonline.com/TECnology-Hall-of-Fame/teletronix-la2a-amplifier-090106/

  Bill Putnam's sons still make LA-2A variants, and their company's website has a nice history of the compressor:
  http://www.uaudio.com/blog/la-2a-analog-obsession/

  Speaking of Bill Putnam and his impressive studio and equipment empire, the companies' internal newsletters from the 60s and early 70s have been scanned and are here:
  http://studioelectronics.biz/URCNewsletterindex-13.html

  -- Tom Fine

• There is a book by a man named Jahnsen on how to build a LA-2A which is exceptionally detailed. It's floating as a .pdf out there if you look since he died.

  All recording engineers should be required to build a mic pre themselves not using any salvaged boards or subassemblies. It is not that hard and many designs are out there.

• Bauer was famous for selling a one kW broadcast transmitter as a kit. They had a secretary build one at a NAB convention in about three days. Like the Gates BC-1 series it used four big tubes, two as RF finals and two as modulators. (They were Eimac tetrodes however.) You rotated them every year.

  This idea goes back to ERPI Restrum Erectric theater amps which used the same triodes used as finals for rectifiers.

  • hi phil. tell us more! there's nothing on the 'net re Bauer. fill us in... . c.

• Radio World a trade newspaper with great articles had a full length article on the Bauer 707.

  http://www.radioworld.com/article/bauers--radio-from-a-kit/14869

  From eham.net:

  Time owned: more than 12 months
  The Bauer 707 is designed for commercial AM broadcast radio service. Due to it's low initial price and availability as a kit in the day the 707 proved to be a very popular transmitter for many AM broadcasters around the globe. Many of them are still on the air today. Modification for 160/80 meter use is fairly simple, to move it to 40/20 is more difficult. Modification details are readily available on line. To effect these modifications you will need a good working knowledge of electronics and have good fabrications skills. In my case I opted to make as few 'Black & Decker” modifications as possible and keep the rig looking original opting to use vacuum relays and stepper motors to allow for quick precise tuning of the rig from band to band. Originally this transmitter was crystal controlled – after all it would spend it's working life on a single frequency, however I modified the rig to accept the output from an old Kenwood VFO, to reduce complexity you could use a synthesized ham rig as an exciter bypassing the oscillator and driving the buffer stage directly.

  When you receive your Bauer 707 from a broadcaster it's pretty typical to find them dirty, modified and in less than perfect working condition, so plan on some serious cleaning and repair. Approach this as a 6 month project, it's not a grab it and go sort of thing, so if you are an instant gratification type don't go this route. You will need a fair amount of space to work on the transmitter as well as a source of 240 volts AC at 20 amps for operation.

  In addition to the transmitter you will need some other equipment. Since the transmitter is capable of over 100% modulation (and creating a great deal of splatter on the bands) an effective broadcast grade audio processor is needed. This can be as simple as a classic single band processor from the 50's like a Gates 39 peak limiter/Level Devil combo, a Dorrough 310, Urei BL-40 Modulimiter, PR&E Modumax, CRL 900/950 series AM limiter to something much more modern like an Optimod 9000/9100 AM audio processor. These will provide much more precise modulation control than a “musician grade” compressor/limiter like a Beringer or DBX. I used a Dorrough 310 with mine with excellent results. You will also need some sort of microphone preamp, I went with a small 5 pot Gates “Studioette” console – a cool art deco looking thing that after a complete refurb was great! But something as simple as a small Mackie will work as well.

  Once you are getting ready to go on the air – you need to consider that the rig is capable of a frequency response well over 10 KHz which will use well over 20 KHz worth of spectrum bandwidth – although very Hi-Fi it's extreme overkill for ham use – and is useless as most receivers tuned to your signal will only pass a small lower portion of this. Really – be a good ham neighbor and put a sharp cut-off low pass 3 KHz filter in the audio chain . While on audio- the transmitter requires a fairly stout audio signal to drive the modulator – the audio processor will provide this drive with no problem.

  So, if you have the space, have the technical ability and don't mind breaking the FCC rules regarding power and emission standards get one today. There are other rigs from RCA, Collins and General Electric which are even classier, but will cost more."

  Barry Mishkind posits thus:
  http://www.oldradio.com/archives/hardware/bauer.htm