29-09-2011, 08:41 PM
I think there's a real irony in Hunts making a cap analyser when just about every duff cap which fails a leakage test was made by Hunts too! But that said, they were a major manufacturers, and the caps have given good service over many decades, far beyond their expected or claimed life-span, so maybe we shouldn't be too harsh on them.
In yet another moment of weakness, nostalgia has triumpherd over commonsense and I recently acquired a Heahtkit C3-U ('U' meaning UK version) Res/Cap bridge which I'm in the process of fettling up. The HT voltages were much lower than the specified +150V and -410V, and apart from the two electrolytic smoothing caps being shot, so was the 'Sentercel' stick rectifier. It was just a series of small discs in a paxolin tube, so I took the discs out and stuffed the tube with a 1N5401 rectifier diode with a series resistor to provide the correct voltages and replaced the two 8uF 500V smoothing caps. I replaced other caps, and I've fiddled about with the resistors in the chain which provides a range of voltages for the leakage test, but I doubt that the voltages were ever that accurate from new. Not important really, as long as caps can be tested at or near their rated working voltage.
The US version uses a valve rectifier and a 1629 magic eye - the UK version uses an EM34, which luckily, is OK, as a replacement would cost me as much as a paid for the C3-U!
I've attached some pics of the Sentercel which might be of interest.
In yet another moment of weakness, nostalgia has triumpherd over commonsense and I recently acquired a Heahtkit C3-U ('U' meaning UK version) Res/Cap bridge which I'm in the process of fettling up. The HT voltages were much lower than the specified +150V and -410V, and apart from the two electrolytic smoothing caps being shot, so was the 'Sentercel' stick rectifier. It was just a series of small discs in a paxolin tube, so I took the discs out and stuffed the tube with a 1N5401 rectifier diode with a series resistor to provide the correct voltages and replaced the two 8uF 500V smoothing caps. I replaced other caps, and I've fiddled about with the resistors in the chain which provides a range of voltages for the leakage test, but I doubt that the voltages were ever that accurate from new. Not important really, as long as caps can be tested at or near their rated working voltage.
The US version uses a valve rectifier and a 1629 magic eye - the UK version uses an EM34, which luckily, is OK, as a replacement would cost me as much as a paid for the C3-U!
I've attached some pics of the Sentercel which might be of interest.
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
