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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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20th Sep 2018, 10:48 am | #1 |
Nonode
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,384
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Advance E2 Sig Gen Mains Transformer
Hello,
I have purchased an Advance E2 Sig Gen. It's a bit scruffy but all the parts are there. The 6X5GT rectifier has tested U/S at 35%/22% and 25M cathode leakage but I have a good spare. The 6SN7GT is 100%. The 6J6 has internal shorts so I've ordered a replacement. I've downloaded the circuit from this Forum and also the Radio Museum and both circuits show a separate heater winding for the rectifier. However, on mine there is only one heater winding feeding all 3 valves. The transformer is almost certainly original - no evidence of past replacement and looks identical to all the pictures I've seen of the internals of those owned by others. I'll live with it for now, but it's not great I guess to have the full HT stress across the cathode/heater of the 6X5GT (one side of the heater winding being earthed to chassis). Any thoughts? I suppose I could fit another heater transformer for the rectifier as there is enough room for a small one. Cheers, Jerry |
20th Sep 2018, 11:29 am | #2 |
Heptode
Join Date: Jan 2004
Location: Stockport, Greater Manchester, UK.
Posts: 827
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Re: Advance E2 Sig Gen Mains Transformer
The 6X5GT is intended to cope with that, though some proved to be unreliable.
The ex-USSR equivalents of more recent manufacture (6u5c/ 6C5S) seem OK. |
20th Sep 2018, 3:42 pm | #3 |
Hexode
Join Date: Oct 2012
Location: London, UK.
Posts: 498
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Re: Advance E2 Sig Gen Mains Transformer
Replace the 6X5 with 1N4007 diodes with around 50 to 100 ohm series resistors.
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20th Sep 2018, 4:50 pm | #4 |
Nonode
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,384
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Re: Advance E2 Sig Gen Mains Transformer
Thanks for the advice in the last 2 posts. The 1N4007 solution is easier and cheaper than an extra transformer. I'm just fitting a replacement HT capacitor because the old one had definitely gone south. Also ordered Class Y caps to replace the mains filters. Cheers, Jerry
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24th Sep 2018, 8:19 pm | #5 |
Nonode
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,384
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Re: Advance E2 Sig Gen Mains Transformer
I decided to live with the 6X5GT in the end as it worked well. I had to increase the initial HT dropper (the one connected to the rectifier cathode) from 560R to 1k to get the HT down to limits. About 6 resistors has gone high and the 1000pF capacitors were leaky and were replaced. Finally the mod/CW switch didn't work so that was changed as well. I think this Unit has had quite a hard life, but hopefully will now give a few more years service. Mods please close.
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24th Sep 2018, 8:33 pm | #6 |
Dekatron
Join Date: Aug 2007
Location: W.Butterwick, near Doncaster UK.
Posts: 8,932
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Re: Advance E2 Sig Gen Mains Transformer
For the record I have a E2 Sig Generator for sale,£15 collect from Newark Hamfestival Saturday.
PM if interested
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G8JET BVWS Archivist and Member V.M.A.R.S |
25th Sep 2018, 4:32 pm | #7 |
Nonode
Join Date: Oct 2017
Location: Bristol, UK.
Posts: 2,384
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Re: Advance E2 Sig Gen Mains Transformer
Hi, Thanks for the kind offer, that's very good vfm. I paid more than that for one that needed a lot of work. However, one is all I need.
Cheers, Jerry |