Well I had the R4B opened anyway, so I took some temperature readings on its power transformer.
Normally I run the Drakes off a step-down transformer, so they see the 110VAC they were designed for instead of the 120VAC of today. Turns out not a big diff in the temperature readings: >From the top of the transformer 110VAC 1 hour 102 degrees F 120VAC 1 hour 107 degrees F >From the side of the transformer 110 VAC 20 minutes 114 degrees F 120 VAC 20 minutes 116 degrees F This was with the cover off, and ambient temperature of about 70F. Original electrolytics AFAIK. Chuck, K1OM On Fri, Mar 12, 2010 at 10:02 AM, Garey Barrell <[email protected]>wrote: > Nigel - > > The receiver in question uses full wave rectification, with the exception > of a "zero current" Bias supply which is half-wave. I believe this is the > case in all Drake receivers. > > The transmitter power supplies use voltage doublers, which seems to be > typical of the higher power supplies. I assume at least part of the reason > is it's easier to wind 400 turns of #20 wire than 800 turns of #30 without > breakage. I don't think copper prices were as significant then as they are > now, but ... > > > 73, Garey - K4OAH > Glen Allen, VA > > Drake 2-B, 4-B, C-Line& TR-4/C Service Supplement CDs > <www.k4oah.com> > > > Nigel Gunn G8IFF/W8IFF wrote: > >> I beleive that one of the main causees of transformer heating appears to >> be the use of half wave rectification and half wave voltage multipliers. It >> saves on diodes, causes lousy voltage regulation and can cause core >> saturation in the mains transformer if the seondary current increases. >> >> This seems more prevalent in US than UK equipment which, unless extremely >> cheap, always seems to use full wave rectification. >> Don't know which Drake tended to use. Probably a mixture of both. >> >> >> > _______________________________________________ > Drakelist mailing list > [email protected] > http://mailman.zerobeat.net/mailman/listinfo/drakelist >
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