[Raleigh]

In my schematics from the Philco 1941 Yearbook, part 57 in the 41-280/285 is a .002 uF condenser between the plates of the two 41 tubes, which is a different way of saying between the white and black wires from the output transformer. Part 68 is a 33 ohm resistor in series with the dial light used only in the 41-287, so ignore it.

In the 41-250/255 schematic, parts 57 and 68 are .003 uF condensers from the plates of each of the 41 tubes to ground.

It's only a guess, but since the 280/285s are consoles with larger speakers, the difference might be to adjust the tone for use with the tabletop and console speakers, maybe to give the larger speaker a brighter sound or reduce boominess. Conversely, maybe they wanted to add bass to the smaller table top speakers.

If it wuz me, I'd leave the 41-285 chassis stock and not modify it to agree with the 41-255 schematic. I used a 41-250 chassis in my 41-280 cabinet for a few weeks while I was recapping my 41-280 chassis without noticing any difference in the tone. Of course, if I understand it right, you're going the other way: using the console chassis in the tabletop cabinet. Still, I think I'd leave it original. If you don't like the tone and can't adjust it to your liking with the bass control, it should be simple to make the change.

One could argue the other way, I suppose, to make the change now and unmake it if the tone isn't satisfactory. After all, you're mixing and matching the chassis and cabinet anyway. Since your chassis is stamped 41-285 I think I'd make a little effort to keep it all 41-285. But I'm only a little bit of a purist. I'd never say leave it original even if it sounds bad. And it's your radio any way you play it.

[MarkBardenwerper]

Thanks for the well informed insights. It looks as If I should get a set of papers for the chassis I am working on. I may find more discrepancies. Does anyone have experience with the many CD's of the entire manual available on Ebay?

[Eliot Ness]

......Does anyone have experience with the many CD's of the entire manual available on Ebay?

If you're referring to Rider manuals the very best are the high-res scans done by KE3GK:

http://www.ebay.com/itm/John-F-Riders-Vi...19d06f89e2

They cost a little more but the scan quality is fantastic.... in fact I'm thinking of selling my hard copies because his are so good.  If you want to see a schematic the seller will e-mail you one so you can compare before you buy. These are big files (4 DVD's) so I transferred them to my hard drive for much faster access.

Here are four samples for you to see the difference between the high res scans and the el-cheapos and freebies out there.


This first one are the el-cheapo Riders that have been converted. I've found the Riders that are free to download are the similar if not the same:

[Image: http://img.photobucket.com/albums/v348/j.../cheap.jpg]

The next comes from a popular on-line source for individual free Rider schematics:

[Image: http://img.photobucket.com/albums/v348/j...OnLine.jpg]

This is from Radio Data which are pretty good but no longer available:

[Image: http://img.photobucket.com/albums/v348/j...ioData.jpg]

This last example is the high-resolution scans from KE3GK:

[Image: http://img.photobucket.com/albums/v348/j.../HiRes.jpg]

Where the high-res scans really shine are when you want to magnify (zoom in) an area to read a component value, etc.  Some of the Rider schematics were poor quality to begin with so these scans won't correct that, but with the better quality of scans I can get by over 90% of the time now without digging out my big manuals.

Another issue is what happens on large fold-out pages.  Every other scanned copy I've seen, including Radio Data, chopped it into two pages with gaps of information missing.  I think KE3GK must have had access to a very large scanner because his come out as one large (and complete) page.  

[MarkBardenwerper]

I now have a decent image of the 285 chassis and a parts list. There is a drastic change in the antenna section. It looks as if the 250 transformer has an additional winding in it. Here are two pics for comparison. First is the 250, next is the 285. I'm wondering if this has to do with the differences in the built in antennas. Should I consider replacing the 285 setup with the one in the 250?

[MarkBardenwerper]

Now, onto the output section. Again the 250 is first and then the 285. The 250 has much lower rated resistors at 53 and 54. 57 and 68 are wired differently as well (the 285 only having one with a slightly different rating). What little brain matter I have that works in this realm is telling me that the lower reistance is going to change the potential across my 41 tubes quite a bit. Mightn't this have to do with the fact that the 250 has a much smaller speaker and so needs to be fed less wattage?

[Mondial]

Resistors 53 and 54 are bias resistors for the 41 output tubes. They don't affect the power output but they may alter the low frequency response. The 1 meg resistors will increase the bass slightly, which might have been necessary with a smaller speaker.

Same thing with the caps across the output transformer. These tune the output circuit affecting the high freq response. The smaller speaker will reproduce the high freqs better so the extra and larger value caps rolled off the treble to compensate.

[MarkBardenwerper]

Thanks. Valuable info. These mods are easy to look after. Same with the antenna mods. I think those have to do with the difference in the antenna array offered in the differing cabinets.