07-05-2022, 03:30 PM
Well, I thought I'd take a quick look with the DMM across the IFTs.
I looked at the first and discovered a loose wire that was near the earth pin of the DIN 3 way socket, which has the "play" directly connected to Gram socket. I traced it back and it went to loads of pins of the base and centre of the EF89 socket!
Ah Ha!!!!
Soldered it instead to nearby chassis tab.
Powered on and VHF-FM stations all blasting in! The EM81 is a bit dim but closes almost completely on a strong station. Our electric is closer to 230 than 220, so I have it on the 240V for longer life.
So I wasn't wrong about final fault being around the IF. Also picking up some non-English station with 2m of wire near HF end of Shortwave, so ECH81 is OK. It goes LOUD. Tone controls work.
The grid leak on the EABC80 triode is 10 M ohm and the series cap goes to the volume control wiper, so though no HT, leakage might be an issue. It's inaccessible, 10nF, so I snipped end at the the valve base and put a 100 nF ceramic cap. Now no faint crackle on volume control.
I wonder how such a set (made for launch of UK VHF-FM) ended up in Co. Limerick? Probably no VHF here (radio or TV) till Dec 1961 or Jan 1962. Even then you'd have needed a good aerial in Limerick City as the TX choice was Mullganish or Maghera. Must have been late 1980s or early 1990s, I forget, when Limerick City, Shannon Estuary and nearby Clare and Limerick got a local mast at Woodcock. You can get Limerick's Live 95FM nearly as far as Portlaoise now.
I looked at the first and discovered a loose wire that was near the earth pin of the DIN 3 way socket, which has the "play" directly connected to Gram socket. I traced it back and it went to loads of pins of the base and centre of the EF89 socket!
Ah Ha!!!!
Soldered it instead to nearby chassis tab.
Powered on and VHF-FM stations all blasting in! The EM81 is a bit dim but closes almost completely on a strong station. Our electric is closer to 230 than 220, so I have it on the 240V for longer life.
So I wasn't wrong about final fault being around the IF. Also picking up some non-English station with 2m of wire near HF end of Shortwave, so ECH81 is OK. It goes LOUD. Tone controls work.
The grid leak on the EABC80 triode is 10 M ohm and the series cap goes to the volume control wiper, so though no HT, leakage might be an issue. It's inaccessible, 10nF, so I snipped end at the the valve base and put a 100 nF ceramic cap. Now no faint crackle on volume control.
I wonder how such a set (made for launch of UK VHF-FM) ended up in Co. Limerick? Probably no VHF here (radio or TV) till Dec 1961 or Jan 1962. Even then you'd have needed a good aerial in Limerick City as the TX choice was Mullganish or Maghera. Must have been late 1980s or early 1990s, I forget, when Limerick City, Shannon Estuary and nearby Clare and Limerick got a local mast at Woodcock. You can get Limerick's Live 95FM nearly as far as Portlaoise now.
