Pilot Major Maestro IF coil trouble - UK Vintage Radio Repair and Restoration Discussion Forum

Atlantic 52 · 27th Nov 2017, 11:25 pm

Hi All,
I have acquired a nice 1940 version (MW & SW) of this radio that had not been used for a very long time. I have restored a fair bit of the set to run it but when I found that V1 wouldn't oscillate I found that the 1st IF coil secondary, L10, reads about 600K ohms and rather suprisingly the secondary of the 2nd IF, L12 is open circuit! I am amazed at this bad luck. The set hadn't obviously been stored badly or 'got at' and wondered if the IF coils on these sets are known for weakness or 'green spot' troubles. If anyone can help me find replacement coils I'd love to hear from them. The IF frequency on this set should be 451 KHz. Trader sheet is 479.
Thanks.

Sideband · 27th Nov 2017, 11:42 pm

I don't think they suffer any more than other radio's. Chances are it's been damp at some time or subjected to wide temperature changes. Might be worth taking the transformers out, removing the cans and checking the thin wires where they connect to the tags. You might be lucky.

Boater Sam · 28th Nov 2017, 12:32 am

I've had some IFs where the coil former has twisted when the twiddler played with it, snapping the fine wires off the solder tags, you may get lucky and be able to reconnect the ends.

Atlantic 52 · 28th Nov 2017, 1:50 pm

Thanks for the suggestions Gentlemen, I'll take out the coils and have a microscopic inspection.
- George

Sideband · 28th Nov 2017, 2:42 pm

After 70 odd years, you could hardly call this a 'weakness'! They are well past their design life.

Atlantic 52 · 28th Nov 2017, 8:18 pm

Gents,
I have managed to repair the 2nd IFT L12, the lead wire was bad under the wax! So, with that repaired I now have IFT1 to worry about. I took it to pieces and examined it very carefully under high magification. Nothing obviously wrong with what is visible so I guess it's beyond a simple repair. Would anyone in the forum be able to help in finding me a suitable substitute? The IF is 451KHz and both windings should be about 9 ohms.
I enclose some photos so you can see it.
Many thanks,
George

27th Nov 2017, 11:25 pm	#1
Atlantic 52 Pentode Join Date: Feb 2014 Location: Aldershot, Hampshire, UK. Posts: 108	Pilot Major Maestro IF coil trouble Hi All, I have acquired a nice 1940 version (MW & SW) of this radio that had not been used for a very long time. I have restored a fair bit of the set to run it but when I found that V1 wouldn't oscillate I found that the 1st IF coil secondary, L10, reads about 600K ohms and rather suprisingly the secondary of the 2nd IF, L12 is open circuit! I am amazed at this bad luck. The set hadn't obviously been stored badly or 'got at' and wondered if the IF coils on these sets are known for weakness or 'green spot' troubles. If anyone can help me find replacement coils I'd love to hear from them. The IF frequency on this set should be 451 KHz. Trader sheet is 479. Thanks.

27th Nov 2017, 11:42 pm	#2
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,580	Re: Pilot Major Maestro IF coil trouble I don't think they suffer any more than other radio's. Chances are it's been damp at some time or subjected to wide temperature changes. Might be worth taking the transformers out, removing the cans and checking the thin wires where they connect to the tags. You might be lucky. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

28th Nov 2017, 12:32 am	#3
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: Pilot Major Maestro IF coil trouble I've had some IFs where the coil former has twisted when the twiddler played with it, snapping the fine wires off the solder tags, you may get lucky and be able to reconnect the ends.

28th Nov 2017, 1:50 pm	#4
Atlantic 52 Pentode Join Date: Feb 2014 Location: Aldershot, Hampshire, UK. Posts: 108	Re: Pilot Major Maestro IF coil trouble Thanks for the suggestions Gentlemen, I'll take out the coils and have a microscopic inspection. - George

28th Nov 2017, 2:42 pm	#5
Sideband Dekatron Join Date: Oct 2003 Location: Croydon, Surrey, UK. Posts: 7,580	Re: Pilot Major Maestro IF coil trouble After 70 odd years, you could hardly call this a 'weakness'! They are well past their design life. __________________ There are lots of brilliant keyboard players and then there is Rick Wakeman.....

28th Nov 2017, 8:18 pm	#6
Atlantic 52 Pentode Join Date: Feb 2014 Location: Aldershot, Hampshire, UK. Posts: 108	Re: Pilot Major Maestro IF coil trouble Gents, I have managed to repair the 2nd IFT L12, the lead wire was bad under the wax! So, with that repaired I now have IFT1 to worry about. I took it to pieces and examined it very carefully under high magification. Nothing obviously wrong with what is visible so I guess it's beyond a simple repair. Would anyone in the forum be able to help in finding me a suitable substitute? The IF is 451KHz and both windings should be about 9 ohms. I enclose some photos so you can see it. Many thanks, George Attached Thumbnails