The STC for an Alternator with a piggy-back vacuum pump (which is also approved for the Cessna, both Continental and Franklin powered airplanes) is owned by Universal Tow-All. The last contact info I had for them was:
Universal Tow-All
3719 Commercial Way
Springhill, FL 34606
ph: 352-666-2929
fax: 352-666-2927
An alternate address is:
3312 Mustang Dr.
Brooksville, FL 34609
This mod consists of a 45 Amp alternator with a vacuum pad on it's rear for an Airborne 211CC pump. It's an interesting idea. (I also imagine it's a challenging situation the day the alternator drive fails, and all gyro systems, both the vacuum and the electric gyros are in a failure mode as well. Battery power alone will be running any electric systems.)
Another possible source for an alternator-only conversion:
Jasco/Skytronics
800-421-6846 (US) or in Calif: 800-872-1101.
It might be helpful to remember that generators/alternators main job is to support constant electrical loads, usually providing about 80% of total electrical demand. If your total electrical loads (everything on except the taxi/landing lights) is only 20% greater than your gen/alt's capability, then you're likely OK. It's not necessary in most cases to keep the battery charged up while taxi/lndg lites are on. The gen/alt will catch up and recharge the battery during the time that the taxi/lndg lites are extringuished.
The most common complaint is during long taxies at night, and while enduring long "hold short" periods at night. If you leave your taxi/lndg lites ON the entire time during such periods you might suffer a slightly low battery voltage after a period of time,...depending upon whether or not you are also attempting to broadcast/transmit on the radio under such conditions. Usually all that is necessary is to increase RPM to allow the gen/alt to raise the voltage back up,...or to switch off the taxi and/or lndg. lite(s).
If operating a VFR airplane, and this was my only problem....I'd seriously consider upgrading to the 35 Amp generator,...as it's considerably less expensive than an alternator conversion. (Probably in the $200-$400 range, possibly even less.)
When these airplanes were under current production, the radios available were high-draw vacuum tube units. Modern solid state radios draw much less power than those originally available. It's very unusual, when using modern radios, for it to be possible to exceed the capability of the original generator systems.
While alternators are lightweight and capable of producing more ampereage... they are also incapable of sustaining voltage fluctuations and/or polarity reversals without expensive damage. Additionally, a discharged battery cannot be re-charged by an alternator merely by propping the airplane, unlike generator systems which will do just fine. If you leave your master sw. on, with an alternator, you'll need to either remove the battery for recharge, or you'll need to risk a "jump" from another vehicle, and the attendant damage that can cause.
(Does it sound as if I'm a fan of generators?)
