SX-28 Band Switch

[W7SOE]

Hi
I am confused, trying to correlate the SX-28 schematic to what I see in the first RF section.  My radio has two wafer switches in the first RF section.  I find images from other SX-28s where there appear to be three.
I found the "old" SX-28 schematic on BAMA (Mine is a 1941 model).  I thought that it was a match except that it shows trimmer caps in the first RF section where mine has none.

I have attached a picture of mine here.

Thanks for the help.

Rich

[W7SOE]

Here is the same section with a different arrangement, from a later model I presume...

Rich

[W7SOE]

I have found an answer from this website:
http://www.radioblvd.com/SX28Notes.html



1st RF coils have trimmers (Bands 3-6) - This was probably a schematic error although trimmers are shown on 1940 and 1941 versions. Even the earliest manual's photo of the chassis underside show that no trimmers were used on these four coils.

[KB2WIG]

R

Good luck with your '28. They are wonder full machines, er, radios.  I listen to 740 kc, CFZM on a big old stereo speaker. The audio is excellent fer da oldies.

Take plenty of pictures and wiring diagrams. When I rebuilt mine, everything worked fine. Except I had this little, little brass washer that goes onto the band switch, left over. If you would take a photo of where it is on yours, I would be very happy. ( if there is one at all) Also, don't make a mistake when re inserting the shaft into the radio. I squashed part of the phenolic on one of the band switch  wafers.....


klc

[W7SOE]

I don't see a brass washer except a rather thick one between the circlip and the outer retaining plate, if that makes sense.

Rich

[KB2WIG]

R,

Thanks fer looking.  The 'washer' on my '28 is very thin. It somewhere between the thickness of a post it note and a index card, closer to the index card.... After I replaced most of the components in the '28 I went out and purchased an digi camera..... This was about 10 years or so ago.


klc

[W6MQI]

Hi Rich,
 Good luck on your SX-28 restoration I did mine about four years ago a complete over haul all new caps, and resistors lots of work. Looks like we may have the same model 28 mine is a non A version pre war.

73, Dave