Looking for a circuit for subject radio. Has six valves; lettering is not clear, but can make out 12 on some and 6AQ5 on another. I think the radio may have been made by Astor. It is very much in need of a thorough check and replacement of caps so a circuit would be very helpful.

With the genuine fit Radio's, often the data is in the factory workshop manual (Event the Humpy Holden). I have serviced a few Ford ones and the Astors.

AirChief I have dealt with and technically that is GMH "NASCO" original and "Firestone Tyre & Rubber" USA

Not Astor unless built under licence.

The Air Chief in my Holden HQ Belmont was AWA.

Solid state, one large power transistor mounted externally using the outer case as a heatsink.

If memory cells still OK I am certain the mentioned transistor was germanium (AD XXXX I think)

Excellent radio, I might add.

Excellent radio, I might add

Aussie AM car radios generally had great sensitivity and selectivity to cope with local conditions and distances.

Astor made a universal type in 6V and 12V the power supplies were different & there were a couple of versions & I have wound up with all of them. The number is on the side of the unit & some you need to flip off the top & bottom cover.

The changeable façade & dial is different according to the car it was in. Many were a "hotch potch" with conventional mains HT valves, others with 12V HT valves and a mix of 12V & 6V heater valves, Valve front ends & transistor audio, often 2N301.

The trap lies in the input. All of the ones with Solid State (Transistors) Had "spark plates" to cater for the 200+V riding on supply from the back EMF spikes from "Kettering Ignition" .

For the FE that would probably be an Astor BJS. Or the rare but similar AJS.

I seem to remember that there was a version of this radio that did NOT use 12v valves but had the 6 volt heaters in series-parallel.

Circuits are here:

http://www.kevinchant.com/astor--air-chief--eil--diamond-dot.html

Most common fault with these (I fixed a lot of them when I was a kid) was the .0082μF 2Kv cap across the vibrator transformer secondary. This is no ordinary cap, it is a special high current type and performs a very critical role.

Kevin Chant has SS vibrator replacements btw

I used to own a '58 FC that had the late '59 Astor CJR or DJR hybrid radio. A fascinating bit of technology using 12v B+ space charge valves. Much better radio.

The last one I got stuck with was an Astor for an early Ford Zephyr six; some of them had the English Radiomobile (Smiths HMV). CR & CS were what arrived & one had a shorted 6BA6 & there was a factory mod that saw 12BA6 being used & one of them had shorted.

Thanks to all for responding. The link provided by Ian Robertson to Kevin Chant's car radio circuits was very helpful. I am working my way through the circuits and have found a very close match in the Electronics Industries Limited (EIL)1955/56 Model SS.

http://www.kevinchant.com/uploads/7/1/0/8/7108231/ss.pdf

Its chassis layout and construction is nearly identical but will keep looking to see if I can find a EIL 1957 12v model. The radio I have is definitely 12 volt so was a bit thrown by finding a 6AQ5; perhaps put there by mistake, so will check heater voltages to determine whether it should be a 12AQ5.

Whilst there were such things as modifications during production, 6AQ5 was a very common output tube with Astor & AWA. HMV tended to use 6M5.

Do not overlook photos and it would be a surprise if there is no number on it.

Marc

The chassis does have RM98699 stamped on it in two places so it could be model RM. However; according to radiomuseum.org, RM is a 1954 model. I have found the RM/RL files on Kevin Chant's site but my Adobe DC will not open it........says I need Adobe X. Would appreciate the details if anyone can open the RM/RL files.

my Adobe DC will not open it........says I need Adobe X

Are you using Windows?

I've never had any problem opening KC's PDF files. Not familiar with Adobe X. I use Adobe DC version 21.007.blah and it opens KC's RL/RM file no problem.

An alternative to Adobe that I also use is Foxit: https://www.foxit.com/pdf-reader/

Regarding model dates there's this, FWIW: https://www.fefcholden.org.au/techinfo/nasco/comforts/airchief.html

The RM/RL service bulletin is dated April 1954.

GTC. I am using OSX 10.13 and don't have a problem opening most PDFs with Adobe DC...........it has opened most of KC's files but some will not open - will have to look into the problem. I am sure the radio is similar to the 56 SS but I am thrown by the presence of 12v heater valves except for the 6AQ5. Even the rectifier starts with 12 - can't read the rest of the letters but assume it is a12x4. The SS circuit will be a good guide until I find the correct one.

You could try Foxit. Seems it will run on Apple stuff.

I have managed to give the radio a rough check based on the SS circuit........replaced a few caps including the .008 2000v and applied power. Radio worked quite well except for a lot of harsh squealing noise when tuning around 850. The noise varies with volume and is loudest when right on the station. I tuned another radio to 850 and could not hear the noise. I am a self taught amateur and not good at tracing or fixing such problems so any advice would be very much appreciated. Valve line up is: 12BA6, 12AN7, 12BA6, 6AV6, 6BQ5 & 12X4.

Greg