[Heathkit] Question: Limited LMO travel on SB-301

[James M. Walker]

Howdy,
Did you do the alignment setup for the LMO per the SB-301 manual.
Sounds like that needs to be checked. Without manual and those guides
it is hard to describe how to accomplish the correct LMO setup.
Do you have the manual?
Jim
WB2FCN
"3 X SB-301, 1 - SB-303"

----- Original Message -----
From: "Jeffrey L. Bauman" <w8kzw at arrl.net>
To: <heathkit at mailman.qth.net>
Sent: Monday, March 07, 2005 8:47 AM
Subject: [Heathkit] Question: Limited LMO travel on SB-301


> Before I tear this thing apart, I thought I'd "go to the well" to see if
> anyone has had the same problem.
>
> I acquired an exceptional SB-301, but the tuning range is restricted.
>
> The LMO is supposed to tune 500 KC - from X.0 to X.5.  Mine physically
stops
> at X.055 ... in other words, the counterclockwise "end of travel thunk"
> comes too early, and won't let me tune the bottom 55 kc of the band.  The
> clockwise "end of travel thunk" comes where it should.  These "thunks"
both
> sound and feel the same .... as you would expect them to:  solid and
> defined, neither end like the feel / sound of a coil getting caught up
> inside a tube.  The tuning is smooth and unobstructed across the full
range.
>
> All told, I get around 432 kc of mechanical travel instead of 500 kc.
>
> The LMO output is supposed to be from 5.0 to 5.5 Mhz.  Mine ranges from
> appx. 5.014 to 5.444 Mhz.
>
> The readout is correct - a signal transmitted on 7.2 Mhz. is received on
7.2
> Mhz per the dial.
>
> The construction of this receiver is about the best I have ever seen on an
> SB-XXX kit, so I don't think it's a question of shoddy craftsmanship.
> Visual review of the mounting  of the LMO, dial, knob, shaft, and 100KC
> insert into the spiral on the back of the tuning dial all seems to be
> perfect, with no obstructions showing anywhere.
>
> So, that's what I'm looking at ... essentially a perfect LMO, but with
> abbreviated end-to-end travel.
>
> My hope is that I'm just missing something stupid, and it is pointed out
to
> me so I don't completely disassemble the unit if I don't have to.
>
> Thanks in advance for the input.
>
> 73,
> Jeff
> W8KZW
>
>
>
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