Hallicrafters SX-42 tuner lock mechanism (how does it work)?
 

So, this guy emails me a question asking about missing parts on the end of
the tuner shaft, involved in the SX-42 tuner locking mechanism. I remembered
that I have a junker SX-42 chassis in the garage, so I took a couple of
photos (sorry for the blurry one -- it's an auto-focus camera).

http://antiqueradio.org/art/temp/SX-42Brake1.jpg
http://antiqueradio.org/art/temp/SX-42Brake2.jpg

I thought I understood how this worked, but it's 10 years since I rehabbed
my SX-42 and I never paid much attention to it at the time. The junker tuner
is frozen and missing all knobs, so I can't twiddle things around and
experiment.

From the looks of it, the two "wings" toward the left of the first photo can
grab one of two "rotors" on the shaft. A spring between the ends of the
wings pulls them together (second photo). In one position, the wings would
grasp the left rotor and release the right one, and vice versa. There are
"brake pads" for the right rotor.

Question: how does this actually work?

When you rotate the little winged lock knob on the front of the tuner, does
that make the stuff on the far end of the shaft pop in and out, to engage
and disengage the right stuff on the far end of the shaft?

All hints appreciated.

P.S. Don't freak out if you see non-stock components in other parts of the
photos. This chassis was stripped to death by a guy who installed PC boards
and other solid-state stuff to make a homebrew HF receiver.

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Hallicrafters SX-42 tuner lock mechanism (how does it work)?
 

Phil,
I think there is a detail drawing of the gearbox on either BAMA or
the Hallicrafter Collectors website. 73 Mike KF6KXG

Hallicrafters SX-42 tuner lock mechanism (how does it work)?
 

Thanks for the tip. The SX-42 Dial&Gear DJVU file at BAMA gives me nothing
but the boilerplate "this came from BAMA" end page. Perhaps a faulty upload?
I have no problem getting other DJVU files from that site. I have all the
other docs, which say nothing about such mechanical details.

Regards,

Phil

"tchrme" wrote in message
ups.com...
Phil,
I think there is a detail drawing of the gearbox on either BAMA or
the Hallicrafter Collectors website. 73 Mike KF6KXG

Hallicrafters SX-42 tuner lock mechanism (how does it work)?
 

Never mind -- I got it to load this time, and the diagram does answer my
question.

Thx.

Phil