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In Reply to: RE: Bridge vs. Voltage Doubler for 4W SET posted by JKT on February 23, 2015 at 11:39:55
Thank you for your input.I'm trying to actually use all tube rectification to hear the difference for myself rather than only relying on researching and asking.
I don't have a choke...however I have the Damper tubes. I just pulled apart a transformer that was bad...so I now have laminates to wind my own choke.
Now I have a concern- I found that the Freed Transformer may have a short...I just tested it with a 40w light bulb in series with the primary and it faintly lit without any load on the secondaries. Being a 470V center tap...I'm concerned 520V may be too high for the windings under load. (520 due to 120V input rather than the 115V)
(I found 2 other transformers I had that lit the bulb up nice and bright...shorted windings. Socket and 40W bulb- One of the best $4 spent.)
Normality frightens me- its what they use to lure you into the cookie cutter.
Roger
Edits: 02/23/15Follow Ups:
Thank you for your replies.
I am concerned about the high voltage windings being at 520v. Are the ratings for a 470vct 200mA intended only to be used as FWB? Or as a bridge as well?
I returned a different transformer that was shorted. It was used in Fisher 800's as a voltage doubler. I traded it for a K20271 conn organ power tranny... 180v used as a voltage doubler for 475v 350mA
Normality frightens me- its what they use to lure you into the cookie cutter.
Roger
If it's faintly lit,that can be very normal because it does draw current even without a load on the secondary.I would try a 1amp slow blow as TK said but I'm pretty sure that transformer is ok.
"If it measures good and sounds bad, it is bad; if it measures bad and sounds good, you have measured the wrong thing."
- Daniel R. von Recklinghausen
Current through the primary will never be zero. Whether it's normal for the residual draw of a good transformer to faintly light a 40W bulb, I'm not sure. I don't normally do that sort of test. A metered variac (or a Q meter) would provide a more definitive answer. In the absence of those items, you could just plug it into a fused socket at full voltage. If a 1A fuse blows, it's bad.
--------------------------
Buy Chinese. Bury freedom.
It sounds like you have a shorted turn or two in the primary. While it is normal for a transformer's secondary voltage to be higher than specified with no load, the voltages you reported seem overly elevated. Also, it should not be drawing current with no load. Shorted turns in the primary would account for both conditions.
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