SB-102 - more troubles

[Brian Wood]

Well, I took the LMO completely out of the rig, which of course required unsoldering some stuff and disconnecting the front panel. It looks like it will be a real treat getting it back together. I can't even tell what the shaft that pokes out the front is supposed to connect to. It just flops around. Guess I shoulda left it alone. But I am pretty fearless about working on this stuff.

My LMO was evidently built by TRW, and is not spot welded. I was able to remove the bottom cover so I can see the variable cap. Where exactly do I spray the lubricant? About the only thing I can get to is a gizmo that has about 5 cams on it.

Where does one buy DeOxit? Any other suggestions?

Brian

--- kgordon2006 at verizon.net wrote:

From: "Kenneth G. Gordon" <kgordon2006 at verizon.net>
To: Brian Wood <wood at LPBROADBAND.NET>
Cc: HEATH at LISTS.TEMPE.GOV
Subject: Re: SB-102 - more troubles
Date: Tue, 14 Jul 2009 19:47:10 -0700

On 14 Jul 2009 at 11:36, Brian Wood wrote:

> Well, the S-meter is now working great! The final solution was to flip
> the mode switch to CW and back to USB, which means the switch was
> dirty. I now am getting fine readings on band noise and signals of
> various strength.

Good, Brian. It sounds like you need to buy a large-ish can 
of DeOxit and apply it (sparingly) in appropriate places.

> 
> However, another problem has surfaced. Now, as I tune across the band,
> I find it hard to tune a signal in because it "warbles" as I get
> close. I have to move the dial back and forth near the signal until it
> stabilizes. Since the LMO is a preassembled solid-state one, I am
> hesitant to open it up. I suppose the dial could be slipping a little
> and I will check this as soon as I can, although visually it seems OK.
> Before I dig into it, I thought I'd check to see if anyone on the list
> has seen this same problem.

This is and WAS a very common problem with that 
particular LMO. 

I have that problem, and it was mentioned often in the ham 
literature of the time.

Since it is spot-welded shut, you can peel the aluminum foil 
tape off the various access holes and spray some contact 
cleaner or DeOxit into the bearings of the tuning cap.

> The dial calibration is also off pretty far - with the calibrator on,
> I have to move the hairline about 1/2" to the right.

What you need to do to center the hairline is to zero beat 
your calibrator at a 100 Khz point, then CAREFULLY 
loosen the set screw that hold the dial in place, and without 
disturbing the zero, swing the entire dial-plate until the 100 
Khz point is exactly centered.

You will (guess how I know this?) have to do that several 
times until it gets to the correct spot.

> The upper dial is
> off too, which I recall being a typical issue with SB/HW-10x rigs. But
> they don't seem to change with use, so I don't really think they are
> slipping.

Don't worry about that one: it is just supposed to give you 
an indication. It was never intended to be very accurate.

Ken Gordon W7EKB

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