VCCA Home Forums TECHNICAL - GENERAL Radios, Tools, Accessories Circuit diagram & speaker info for car radio

I've come across the following 6 tube radio for my uncles car,but I'm in need of a circuit diagram and some information as to what type of loud speaker is needed.
The following is the only information in can find within the radio itself,and from the aluminium tag on the casing:

The tag reads: Air Chief Auto Radio Model 66

Inside the casing,a paper label has written on it in lead
pencil: Receiver Serial No. 1557664

The other paper label has the following written on it:

Auto Radio Model 980459

The tubes used in the receiver are as follows:

2 X 41,1 X 78,1 X 6F7,1 NU78R,1 X NU85

Any information to help get this receiver up and running again would be gratefully appreciated,and also finding out what type of loudspeaker it should use.The radio is a present for my uncle for his 1935 Chev Sedan,and whilst it's not a genuine Chev accessory,it will still make him a great birthday present.

Best Regards,
Kevin. :)

Try contacting the "AntiqueMechanic" @ chev33radio@comcast.net he is a radio expert and might be able to help.

As he indicates, the radio is an aftermarket radio. I do not recommend that a customer put any money into an aftermarket radio, unless the radio has some significance to the owner.

Correct Chevrolet radios are available for almost every year and model. This is where I recomend they spend their money.

If the radio is special, and I receive the request, I will look up the data for it.

Kevin,

I believe this is a United Motors radio which later became Delco. This radio may have been made for an Oldsmobile. I have emailed schematics directly to you.

Good luck,

Rich

I have checked my files and did not go back that far in aftermarket radios. Sorry!

I feel confident that the radio can be restored without the schematic.

I would have to inspect the radio to make a recommendation on the speaker and mounting.

Ray,

Are you aware of this resource for schematics? The link below will take you to United Motors (Delco).

http://www.nostalgiaair.org/Resources/429/T0000429.htm

Rich

Non of those searches produced an Air Chief Auto Radio Model 66.

Although the Model number 980459 appears to be a Delco number it isn't. From the tube list presented we are in the 1932-36 era. I do not find any United Motors radios that have the proper tube line-up and the proper dates.

Air Chief was most likely a brand carried by, say, Montgomery Wards or Sears Roebuck. Perhaps even Western Auto or OTASCO (Oklahoma Tire and Supply Company.)

Hi RICHK,

You indicated you had sent schematics, where were you lucky enough to find it?

Ray,

Check the link I placed in my previous response (up three.)

Rich

I checked it out and could not find any reference to the AIR CHIEF AUTO RADIO 66 OR anything that checks against 980459. Give me a hint. THANKS!

Ray,

Go way down the list past the area where numbers are first to where Buick, Oldsmobile or Pontiac are listed, then you will find the model number.

I had a tough time finding it too.

http://www.nostalgiaair.org/Resources/560/M0022560.htm

Here is one of the direct links.

Have you used this site before? I have most of the Riders books, but not all of them. This site fills in the gaps for me.

Rich

There it was. Don't know why I was unable to locate it in my files.

I have not used that site before. I only do car radios, and specialize on Chevrolet. I have just about anything that has been printed on the Chevrolet radios. I also have the complete set of the ARs.

Thanks for the guidance.

Ray,

Up to now, I have only done consoles and table top radios. While certainly not an expert, I have been restoring old radios for about 6 years now with pretty good success. My first car radio is for my '37 Chevy. I have an original unit and have just about completed cap. replacement and need to get a solid state vibrator then I will be ready to power it up.

Rich

Just to shed some light on the original subject.

Airchief car radios were Australian made in Melbourne Victoria, by Astor ,a company part of Radio Corporation (Australia).

They were contracted by GMH Australia to produce radios specifically for GM cars, and also sold their own under the ASTOR brand.

The first mention that i know of was the 1934 model.(1934-5 radios had GM-H perferated in the case)
1936 was the first year to use the airchief name, and had an enamel oval badge with the Airchief name , and General Motors Holden's Limited all witten in the badge.

Circuit diagrams for airchief are not easy to find.
1939 astor model EB(more upmarket version of the 1939 aircheif)appearing in Volume 3 of the AORSM , Australian official radio service manual.

I have looked through most AORSM,s from 1937 -1955 for airchief circuits without much luck.
there is ,was .. a website listing AORSM indexes down under.
An option would be to contact a company like Resurrection radio , in Victoria, who specialise in Valve ( sorry tube) radios.
email me a picture if you like??
Jack

Jack,

Thanks for the history lesson. Is it likely that the schematic that I found was correct since there was a match on the model number? If not, I will keep my mouth shut on issues concerning foreign radios.

Thanks,

Rich

Hi Rich,

You may well be correct with the circiut which you have found,Does the TUBE compliment match the description
it certainly is a very good place to start from if you dont have the original circuit to match the radio.

I did this with my 1939 astor radio in my 39 as people wanted me
to pay too much for a photo copy from the AORSM at the time, eventual got a copy from the Mitchell Library (state Library) sydney.

A lot , if not most radio circuit developement was done by RCA (usa) and the circuits for "superhetrodynes", autodynes,ETC were
subject to patent licences and fees.

My 1939 Astor EB uses a push - pull output valve, where my 1939
airchief uses a single sided output stage.

A RCA Valve(sorry Tube) DATA book is also helpful to workout voltages at the various pins on the tubes , with most types covered in these books.

Radio corporation(AUS) was to eventually become Electronic Industries, and eventually were taken over by Phillips Australia.

As Ray has stated the TUBE (valve) compliment is pre metal Octal base so places it prior to 1939.

The original speaker would have been an electrodynamic speaker mounted in a round enclosure mounted on the fire wall, or overhead just behind the windscreen.

The EM speaker uses coil to make the magnet for the speaker. It was part of the filtering circuit of the radio 6 volt power supply.

Permanent magnet(PM) speakers started to appear in 1940.

Speakers PM and EM use an impedence to classify power of the speaker, 3.2 ohm impedence was quite common for tube radios.
Later PM impedances are 4. 8 , 15(16) ohm impedences.

The original speaker can be replaced with a PM , but you need to include a replacement for the electromagnetic coil of the EM speaker to help with the filtering of voltage ups and downs caused by the car generator, and ripple from the vibrator and filtering condensers. This is usually a small choke , which looks like a small tranformer. 4 ohms is normal for the replacement PM, but depends on the output valve(tube) and output transformer.

Hope that isnt to much to comprehend !!!



Regards Jack

Well Guys,

IT LOOKS LIKE WERE ON THE MONEY!!
CJP's29's RADIO IS A "BUICK"(B-O-P) RADIO MODEL 66.
CHECK OUT EBAY ITEM 230261697705. !!!!!!

A circuit schematic should be just around the corner !!!Does your one match "RICH"
cheer Jack

Tube line-up matches.
Shows 78 78 6f7 85 41 41.
If you remove the NU prefix from NU78 and NU85 we have a winner.

The 2 off 41 tubes are the output tubes (valves) and operate
in push - pull arrangement to a centre tapped transformer T7.

Electrodynamic speaker is 8 inch and is on the 6 volt power supply for filtering/ smoothing.
Jack