Wagging DX-35 Meter

[Kenneth G. Gordon]

> Okay, here's the synopsis.  The Shurite-type meters have no damping and 
> wag, but some do it more than others.

Yup. As the proud owner of a DX-35 in 1956, I can attest to that. I got 
mad and replaced my Shurite "moving vane" meter with a Simpson 
D'Arsonval movement one in 1957. Had to adjust the meter calibrating 
resistors, but my Elmer helped me with that.

>  I've noticed it, both with my 
> Johnson Viking Adventurer and DX-35 in the mid 50's, but I don't remember 
> anything nearly as bad as this one has been doing.

I think one of the other guys suggestions was that perhaps one of the 
damping springs had broken loose.

> Take a look at http://www.infodotinc.com/neets/book3/7d.htm from my Google
> search of "d'Arsonval meter" and "damping" that appears to be a segment from
> some kind of training course.

I'll take a look at that.

> 
> I opened up the meter this evening and found that there's a screw below the coil
> that's apparently for bearing tension.  I tightened it slightly and it seemed to
> reduce the oscillation, but unfortunately it appears that I tightened it too
> tightly because when I mounted it back, it stuck.

I did that too...in 1956. Got the same result as you did. Loosened it up a 
bit. Still wagged. Thus the Simpson. Cost me $12.00 then which was 
about a weeks worth of mowing lawns.

> 
> I don't know if this is a possibility, but the results of your good counsel and
> some homework are that the best solution, beside's Stu's excellent suggestion to
> replace it with a DX-40,  may be to find a meter movement that can be adapted to
> the original meter face.  This may be too far-out an idea, but we'll see.  I'll
> let you know what I find out.

Another thing you have to be aware of is that the DX-35's power 
transformer was running "red-lined" in its normal condition. I lost two in 
the space of two years before I got mad again and replaced it with a big 
heavy TV power transformer and that "Economy Power supply" idea 
using a SS bridge rectifier. After that it ran perfectly until I gave it away 
about 10 years later. I even used it for RTTY to drive a modified BC-
610. I had a nice VF-1 I added FSK to. It was nice and stable, even on 
20 meters.

Also, in the DX-35 (and possibly the DX-40) Heathkit used this rather 
silly idea of connecting the oscillator and buffer stages in series directly 
across the +HV line to eliminate "power wasting dropping resistors" as 
their sales literature said. The real reason was that wimpy power 
transformer. When I went the TV transformer route, I got rid of that too. 
All it took was another RF choke and a bypass capacitor. Got the 1/2 
voltage off the center tap of the TV transformer.

BTW, I understand that DX-40s are starting to lose their power 
transformers now too.

Ken W7EKB

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