01-12-2013, 09:47 PM
OK, the Canadian tie in was just a wild guess on my part as to why it has the 230 V option. There is not brass plaque on the back. I did note on the parts list that there was also a 25 Hz transformer option.
ON TO ANOTHER REQUEST REGARDING THIS TRANSFORMER: I've made contact with the Heyboer and removed the transformer from the chassis (taking pictures all the way). The secondary is intact; it ohms out pretty much per-spec as shown on the schematic and it's the primary that smoked. Here's the relevant section of the schematic:
http://i791.photobucket.com/albums/yy193...2a9c3.jpeg
I'm trying to work out what specification I should give Heyboer for the input / output voltage. I think 120Vac for a single primary is reasonable (I've elected to forego the unneeded complication of routing the leads for a dual voltage primary to the top side of the transformer since I'll never use them, and just mount the jumper there for appearence sake). So that leaves the O.C. secondary voltage specification. Starting with a "typical" working plate voltage for the 6L6 output tubes in push-pull and working backwards through the filter components & rectifier. I came up with about 600 Vac (RMS) (300 V from the end to the center tap of the secondary). But to sanity check myself I took a look at the power supply design section of an old radio handbook from that era and the general formulas in there point to just under 500 Vac (250 V end to center tap) as the target secondary voltage for a supply with a capacitive input filter. I don't have anything in my reference material for this set that says what the typical operating values are in circuit. It would be just GREAT if someone who has 38-690 happens to have that information. Lacking that, I open to suggestions.
Under the heading of FWIW, in case you're wondering who you're chatting with, I also uploaded a photo of me taken a few years ago when there was a bit more hair and it wasn't at gray; I think you'll reconginze the little set on the left:
http://i791.photobucket.com/albums/yy193...radios.jpg
ON TO ANOTHER REQUEST REGARDING THIS TRANSFORMER: I've made contact with the Heyboer and removed the transformer from the chassis (taking pictures all the way). The secondary is intact; it ohms out pretty much per-spec as shown on the schematic and it's the primary that smoked. Here's the relevant section of the schematic:
http://i791.photobucket.com/albums/yy193...2a9c3.jpeg
I'm trying to work out what specification I should give Heyboer for the input / output voltage. I think 120Vac for a single primary is reasonable (I've elected to forego the unneeded complication of routing the leads for a dual voltage primary to the top side of the transformer since I'll never use them, and just mount the jumper there for appearence sake). So that leaves the O.C. secondary voltage specification. Starting with a "typical" working plate voltage for the 6L6 output tubes in push-pull and working backwards through the filter components & rectifier. I came up with about 600 Vac (RMS) (300 V from the end to the center tap of the secondary). But to sanity check myself I took a look at the power supply design section of an old radio handbook from that era and the general formulas in there point to just under 500 Vac (250 V end to center tap) as the target secondary voltage for a supply with a capacitive input filter. I don't have anything in my reference material for this set that says what the typical operating values are in circuit. It would be just GREAT if someone who has 38-690 happens to have that information. Lacking that, I open to suggestions.
Under the heading of FWIW, in case you're wondering who you're chatting with, I also uploaded a photo of me taken a few years ago when there was a bit more hair and it wasn't at gray; I think you'll reconginze the little set on the left:
http://i791.photobucket.com/albums/yy193...radios.jpg
Dave Perkins
Old Radios
Old Volvos
and homebrew beer !
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