On May 24, 4:06*pm, "Barry" wrote:
* * I restored one not too long ago. Learned a lot including how to
restring the drive cable. I must have worked on many 606As and Bs when I
worked for Hewlett-Packard many years ago but was appalled that I
remembered so little about them. On mine the rotors of the tuning caps
were decentered and the plates had been severly bent to compensate. I had
to disassemble the thing enough to remove the caps and fix them. I have
just the vaguest memory of something to do with the caps in these guys
having problems. Generally, -hp- stuff of this vintage should set up
better than specs although there were some real dogs such as early 400D/H
voltmeters which were completely redesigned about twice, and some early
200CD oscillators which had several revisions of the circuits particularly
the power supplys. I dont' think there were any really serious revisions
of the 606A but can't be certain.
* * Agilent has many -hp- manuals on line in reasonably hi-res PDF form,
they may have a better copy than you have. There is also some stuff at the
HP Memory Project site.

--
Richard Knoppow
Los Angeles
WB6KBL


Richard,

This is my frist 606A. *I've been digging into this one just trying to get
dust off, etc. *Pretty impressing mechanicals in this thing. *I've rebuilt
some R390As and this thing is just about as much fun. *Love those large
gears that house the oscillator and amplifier coil assemblies.

When I got it, I couldn't turn the range change switch. *It turned out to be
just dried lubricant on a few parts. *I've cleaned and oiled things a bit
and it works great now. *I was very surprised to find calibration to be on
the money for the most part. *I tweaked one range at the upper end and I
think all the others were very close on the lower end. *The only range I
can't bring into spec is the top range. *Not enough L or C to get it rignt
and not sure what to do to correct this.

This one has all HP-branded tubes. *It looks like they may have never been
changed from the factory.

Thanks for the reply,

Barry - N4BUQ

The coils on the highest range are adjustable by squeezing or
stretching them a bit to change the basic inductance. Set the core at
about half way. The coils are cemented to the plastic former with coil
dope, AKA Q-dope. Airplane glue will work in the absence of the real
thing. What happens is that the cement disintegrates and the coils
have enough elastic memory to stretch out and change value.
The frequency calibration should be no worse than half specs.
There were some changes in the crystal calibrator circuit and a
couple of other places, I don't remember all of them.
The assembly comes apart much more easily than it looks. One of
the screws that fastens the front panel onto the chassis is underneath
the modulation meter.
If there is a calibration problem on all bands its likely the
dial has slipped. The procedure then is to get the dial back to where
it belongs. The dial is held in place by a clamp under the main tuning
knob. I don't think you need to do this since all the bands are on but
one.
BTW I found a TV type adjuster with a long, thin section between
the handle and the allen head end that is flexible enough to fit into
the core of the HF coils while they are in operating position.
Otherwise adjusting them is a stepwise chore.
These are very good generators and have the virtue of very low
distortion modulation capable of 100% which makes them valuable for
receiver detector evaluation.

--
Richard Knoppow
Los Angeles