The International Cessna^® 170 Association

My 170 project plane has a voltage regulator marked P & D VR-122H. The engine is the standard 0300A and I have the standard 20 amp generator. I can find nothing on the regulator. Anyone know if this is a usable/acceptable regulator with the 20 amp generator?

Sometimes parts stores can cross-reference based upon part numbers only. I did a search using two software routines I have and it was not recognized.

Read the comments I posted at regarding automotive regulators (for ground test purposes only, of course):
http://www.cessna170.org/forums/viewtop ... tor#p21269

Thanks for the response. I suspected it may be an automotive unit. This plane sat around for a couple of years before I bought it in a somw what disassembled state. I am not even sure this regulator was ever used on this plane. I will replace the regulator. Are the solid state generator regulators recommended? Thanks again for the help.

The solid state units are good generator controllers, and Zeftronics aircraft versions are less expensive than most original units. The original "vibrating points" regulators are more likely to give difficulty but or more easily adjusted in the field if you're a "tinkerer".

If you're not crazy and insistent on originality then the Zeftronics unit is the way to go. Their website is down this morning, but you can buy their units from Spruce also.

Zeftronics
1622 E. Whaley St.
Longview, TX
Phone: 903/758-6661
Fax: 903/236-9766

ZEFTRONICS GEN CONTROL G1200N (Spruce PN 07-00617) $133.95 (20 Amp unit)


If you're putting an airplane back together, it's a great time to upgrade to a 35 Amp gen and reg. Exchange the generator with an 1101898 at Aerotech of Louisville and get the regulator (G1350N, Spruce PN 07-00617) from Spruce, then make sure the wiring from the gen ARMature terminal to the ARMature terminal of the regulator, and the BATtery terminal to the main buss and on to the master solenoid is at least 8 gauge, and protect it with a 35 Amp fuse or C.B., and log it.

http://www.aerotechlou.com/

Aerotech of Louisville
2209 Watterson Trail
Louisville, Kentucky 40299
Phone: 502-263-7090 (local)
Toll Free: 1-800-634-0190

http://www.aircraftspruce.com/ (877) 478-7823

(Caution: Recent reports of accessories obtained from Kelly Aerospace, and or their distributors, have been unsatisfactory. They are experiencing some difficulty in quality control, evidently. Aerotech of Louisville is one of the best sources for overhauled/exhange accessories, but they also are distributors of Kelly units. If you obtain an overhauled alternator or generator from Aerotech then insist on a unit overhauled by Aerotech, not simply a distributed Kelly unit, until further notice.)

I just put on a rebuild generator last night, and just have to bolt on the new sold-state regulator sometime this weekend.(Got tired last night and too cold today). I was looking through the interior and found that the plane had a 25amp fuse for the 35amp generator and regulator. While I was searching were to find these 4ag fuses I came across an article about not using fuses in circuits greater than 30amp, due to the lack of heat displacement. I didn’t know if this a big problem and I should change to a circuit breaker or just use a fuse. I don’t want to make a big project out of this and don’t want to change to all CB. I will attach the article I read, where it talks about this is page 4.

Here is a little excerpt of it.
One of the reasons this alert from the first figure is repeated is to accentuate the statement that fuseholders
are not to be used for fuses of 30 amps or larger, which means that many planes which were converted to
the 35 amp generators should have been changed to a circuit breaker, and all of the 60 amp alternator
circuits should be protected by circuit breakers IF the protective device is of greater than 30 amps capacity.

Thanks

Some fuseholder installations do not allow for proper heat dissipation and will let a 35A fuse "blow" at 33 or 32 amps. The installation allows for it in the case of the generator. You can even use a 40A fuse legally if you use the correct size wire. (Slight over-capacity is allowed... or you can use a "slo-blow" fuse.) Remember, the fuse does not protect the generator or regulator.... it protects the WIRE that serves those circuits.