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Rogers Tuner info needed
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09-10-2014, 01:45 PM
The original smoothing cap might have been a three section job? The WW topside looks like the main filter resistor.
Is there an ID No: on the rectifier? If so you might be able to find out a typical resevior cap value. Lawrence. (09-10-2014, 01:45 PM)pwdrive Wrote: The original smoothing cap might have been a three section job? The WW topside looks like the main filter resistor.will look at that one I get home
10-10-2014, 09:11 AM
(09-10-2014, 01:45 PM)pwdrive Wrote: The original smoothing cap might have been a three section job? The WW topside looks like the main filter resistor. bridge marked 82 50 C75 KC06e 22/8 all valve holders are 9 pin
10-10-2014, 09:23 AM
If the "8" was a "B" then it it might be a Siemens B250 C75 ie: 250v 75ma rectifier.
Lawrence.
10-10-2014, 09:33 AM
A couple of online radio schematics that I looked at seem to indicate a value of 47uf for the resevior cap used with the B250C75 rectifier.
Lawrence.
10-10-2014, 09:34 AM
That sounds reasonable. I would think the capacitor would have sections of 8 or 16uF which would be adequate for this application and would be the typical value for smoothing caps at the time it was made.
Keith
10-10-2014, 09:47 AM
I reckon this and that are the same:
http://www.diyaudio.com/forums/parts/179...ifier.html Lawrence.
10-10-2014, 11:00 AM
From the pictures there appears to be a feed from the discriminator to the grid of the triode section of the IF valve (via a network), the anode of that valve is connected to the anode of the triode section of the mixer/osc valve, I wonder if it's a reactance valve?
Lawrence.
10-10-2014, 12:54 PM
(10-10-2014, 09:34 AM)Keithstv Wrote: That sounds reasonable. I would think the capacitor would have sections of 8 or 16uF which would be adequate for this application and would be the typical value for smoothing caps at the time it was made. I'm no expert on valves and have limited experience beyond restoring several Hacker Mayflowers, but I will say that the Mayflower uses a dual section 47uF smoother. Now the Mayflower has a 7 watt push-pull output stage. With that in mind, 47uF - while OK as far as the rectifier might be concerned - seems overly large for this tuner. I'd be inclined to agree with Keith's suggestion  It is surprising that no-one appears to have a schematic. Rogers were well-known and highly regarded, and plenty were sold. I've enjoyed viewing the pictures - it does seem to be a well-made unit. Interesting that they didn't simply buy-in a continental front end. Looking forward to hearing how this restoration goes... |
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