[Hammarlund] HP 606A

[Chuck McGregor]

Mike -
When I worked at Hughes Aircraft in the mid -60's synthesizers were very 
new and very expensive and very rare.  In the RF-IF signal processing 
circuits lab we used HP606 generators with an outboard 10:1 vernier mounted 
in place of the HP vernier knob.  With a little patience for the backlash, 
we normally dialed the generators in to within 1 cps at 30 Mc !  (Yes, this 
was also a year or two before Hertz replaced cps).  After the first half 
hour for warmup, we very rarely had to touch up the frequency setting. We 
were measuring frequency with HP 524 frequency counters - about the size of 
a small refrigerator.  With a HP606, a HP524 and a Tektronix 545 at each 
workbench, heat buildup in the lab got pretty bad by late afternoon. Much 
good work was done with that equipment, all long since gone to surplus.

The only performance weakness I remember from the 606 was that the AM 
modulation had a very significant amount of FM - enough to create some very 
interesting asymetrical line spectra.

--Chuck N7RHU


At 11:17 PM 10/22/2002 -0500, Mike McCoy wrote:
>A while back I was asking about aligning an HQ-180. I asked what I should
>look for in a signal generator. While a few recomended the HP 606A, I
>replied that I preferred something a little less weighty.
>
>Well, as fate would have it I couldn't resist picking up an absolutely
>immaculate HP 606A. It cost me $100 (shipping was largest part of that) but
>after cleaning off the dust it looks almost brand new and is stable/solid as
>a rock.
>
>Anyway, for those with an HP 606A (or thereabouts) my question is this: It
>might just be me not being used to it but it seems the vernier is really
>'free' and therefore adjustments are really touchy. Much more 'sensitive'
>than I would think a vernier has any right to be. It's a simple mechanical
>link via a small gear to the (very) large main frequency gear and I don't
>see any shaft adjustment and/or friction type device to 'tighten' it up.
>
>Anyway, it's almost impossible to dial it in better than +/- 10-20 hz. I'm
>thinking a felt pad under the knob itself might eliminate the 'backlash'
>and/or provide a tighter feel. With a tighter vernier I'm sure I could nail
>any frequency I wanted.
>
>Or am I just 'digitally spoiled'?
>
>If you have any tips/tricks to share about this ol boatanchor please feel
>free to email me directly (to keep the list on topic).
>
>Thanks,
>Mike
>
>
>
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