Glad to hear your back on it Raymond. I will be keeping an eye as the progress continues.
Jerry

Well Jerry, I have to find a junk 9X641 so I can pluck out the RF coil and oscillator coil to add to my chassis. Also those newer IF cans measuring 3/4 x 2" are known for having failures so I'll be using the older and larger IF cans. If not for the IF can issue, all I'd have to do is change the dial scale back plate to enable the chassis to fit the desired cabinet. The wife really likes the 56X2 cabinet style so I'm custom building it for her. When finished, it will have a solid-state regulator and be a hybrid between the 9X641 (RF amp) and 56X2 (cabinet). I plan on painting it candy apple red. Unfortunately at the rate I'm moving, it will be a late birthday gift.

May Update
In spite of all the distractions and multiple projects going at once, I've finally got the chassis mapping completed in Excel. It turned out to be more elaborate than anticipated with each sheet having 12 columns listing item name, pin or lug number, from and to locations, lead lengths and colors, and check-off boxes for progress and number of leads to solder. Seven pages in all that includes tube sockets, resistors, capacitors, other parts, bare wires, insulated wires, etc. I was going to post it here on the blog but the 256K size limit prevents the posting of anything readable. I might have to put them over on my yahoo flickr account.

June Update
The project has been abandoned as the focus has shifted to the RCA models with aluminum chassis and RF stage such as the 9X641. Parts like speaker, volume control, output transformer, and IF transformers have been salvaged off the RCA 56X2 for use on the 9X641.

Silver Migration
Rather than rebuild the smaller 3/4 x 3/4 IF cans and add outboard capacitors, I'm substituting the older 1.25 x 1.25 IF transformers from the RCA 56X.. series radios. These use two screw adjusted trimmer capacitors (both on top) rather than the annoying easily broken powdered iron slugs at each end. Tube socket spacing is the same so the smaller IF cans can easily be removed and replaced with the older style by simply drilling a few new chassis holes. Of course there are wires rather than solder lugs so a 4-terminal strip will be added to facilitate connections.

It's always a good idea to touch up the 455 KHz IF frequency after a radical change but at this rather low frequency, wire length and placement is not at all critical. The same tubes are being used so impedance matching is not an issue.

Yes.. but after you replace the caps on those original 3/4"x3/4" IF cans ...you should only have to readjust the cores once.... right?

Yes, I would assume so. But if the adjustment tool is not the correct size, those powdered iron slugs are easily chipped away. In a pinch, you can get away with adjusting using an orange stick provided the stick fits into the bottom of the can and has had the end filed and shaped to match the core slot. Needless to say, you never want to adjust using a metal screwdriver.

The last time I went after silver migration, I could actually see blue sparks arcing across one of the caps by looking through the clip slot on the side of the can with the lights turned off. After cutting the defective can out, I substituted one of the larger 1.25 inch cans that was rebuilt with new wire leads. With the can temporarily attached to the edge of the chassis with two alligator clips, I tack-soldered the various leads to their locations as a test. The leads were way too long, about 6 inches each and I didn't bother to get the signal generator out. With the tuning capacitor about midway on a dead spot, I adjusted the IF trimmers for peak noise and they were right on --no adjustment necessary. So, it appears that lead length and placement is not at all critical.

Right now, I'm upgrading a salvaged 9X641 chassis with the older style IF cans, a dial scale back plate from a 56X2 and drilling a chassis hole to add the tone switch. The object is to put the 9X641 (having aluminum chassis and RF stage) into a salvaged 56X2 cabinet. I have a long grueling list of things that need to be done before the reconfiguration is finished and the chassis slides into it's new home. I do a little at a time when I'm in the mood --between beer's of course. This is going to be a gift for the wife because she thinks the 56X2 box is cute. She knows better than to ask when it will be finished.

The 2X61 is also a nice two-hole radio with RF stage but has a steel rather than aluminum chassis. They're pretty good for salvage since the dial scale is usually faded and cracked. If you're lucky, you can find one with a good speaker and usable volume control. But when you buy junk on eBay, you often find people that like to take all their rusted & defective tubes and stick them into their "for parts or salvage" sales.

So use the right tool and you'll have no need to go swapping out IF cans.... just because you "might" crumble a core.

A complete set of adjustment tools to fit every possible size and then some.. is available at any electronics source for a couple bucks.

Re: So use the right tool and you'll have no need to go swapping out IF cans.... just because you "might" crumble a core.

===================

Yes, I've done that but I like the older IF cans because they have both porcelain trimmers on the top where they're easy to reach. It's just a preference for this particular project.

Okay.. yes sure I understand i got that..
just remember.. you'll only need to adj the IF once... lol

What? You mean I shouldn't place a tuning knob on top of the IF can?

All projects are back on the shelf, probably until fall. It's going to be in the 90's all week with high humidity so I won't be doing any soldering or desoldering.

I don't know where you live, or how. But most folks today seem not to have too much difficulty soldering or cooking or even doing almost any kind of light indoor work in the Summer as most folks around the country these days have their homes air-conditioned.

LOVE that knob on top of the IF !!

If I adjust that knob just right, I can pick up WWV

http://tf.nist.gov/timefreq/images/radi ... way2nd.jpg

You do know... that if you're feeling a little creative and want to have a bit of fun... you can simple MAKE you own home-brew IF quite easily.
I did it and had great success immediately!
Here's my first one:
viewtopic.php?f=6&t=86652


And here's my 2nd one:
http://antiqueradios.com/forums/viewtopic.php?t=86553


I got the idea from this site:
http://www.angelfire.com/electronic/fun ... Can-1.html

Very interesting, Peter. How does the electrical flux transfer from the primary to the secondary though? In a conventional IF, it's through coil induction...

Thanks ...
What makes you think this is any different?

The flux transfer is still happening between the inductor-coils. (conformal molded chokes)

The tiny (ferrite-core-type) primary and 2ndary coils are placed side by side in close proximity. I adjusted the distance while watching the scope for maximum coupling.

From what I understand, these (conformal molded chokes - 250 wvdc) coils are wound on a "barbell-shaped" ferrite core causing the maximum effect of inductive coupling out and off to the sides not top and bottom.

In the 2nd example I show the primary and secondary (1.2Mh each) coils placed side by side and positioned for max coupling.

In the 1st example you'll notice I am using two coils in series to add up to 1.68Mh (1000uh + 680uh)

So The primary uses 1.68MH and the 2ndary also uses 1.68Mh... the two sets of coils are also place in parallel and positioned for best coupling.

I suggest you try building one... it's extremely simple.. fun and educational... AND satisfying.

Yeah, the first circuit threw me off a little, with the cascading coils. So it's critical for the coil spacing, eh? Sounds logical.

I can see the second rig placed vertically inside an IF can, with holes in the side, ALA European style, for the cap adjustments. Do you think a metal can enclosure would have any bearing on it's performance, + or - ?

Conventional older style IF cans have the (pie-wound) primary and 2ndary coils positioned above and below each other
But ...
From what I understand, these coils (conformal molded chokes -rated 250wvdc ) are wound on a "barbell-shaped" ferrite core causing the maximum effect of inductive coupling out and off to the sides not top and bottom.

Right, so placing your setup, exactly as it is, in a vertical position, shouldn't have any detrimental effect on it's performance.

I was simply wondering if then placing an IF can enclosure around it would have any additional effect, either positive or negative.

First you need to ask yourself why the original IFs required a metal enclosure.. right? They probably radiated outward quite a bit.
You may find with these style that the whole thing doesn't radiate out very far at all and might not need any type of metal enclosure at all.
But go ahead and try it.
Experimenting is ALL the fun.

That's what I love.. I enjoy trying out little ideas like these. Surprising (if you read my other thread on these) how many guys here learned a lot and got excited about the idea.