Hi Eddy -
I don't think the 'grounding' problem is related to 'ohmic / dc' grounding. I believe the 'RF'
grounding, i.e., WHERE the ground is applied, is what is at play. The core itself is extremely
critical in both mechanical and electrical grounding. The other part of the problem is that 'bad'
doesn't necessarily mean 'less' grounding, i.e., just 'changing' a ground path may cause a problem,
or cure it. It's the 'change' that shifts the frequency.
I'm wondering about weak springs from the yoke to the can. We're talking just minute changes, such
as 50 - 100 Hz out of 5,500,000 Hz. A LOT by crystal oscillator standards, not so much variable
oscillators. The problem is that it is a 'step' change rather than a smooth 'drift'.
73, Garey - K4OAH
Glen Allen, VA
Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line
and TR-4/C Service Supplement CDs
<www.k4oah.com>
Eddy Swynar wrote:
On 2011-07-29, at 11:10 AM, Garey Barrell wrote:
The yoke is probably THE most sensitive mechanical point of the PTO. The yoke
/ rider bar must be clean and unlubricated so that a constant ground is
present. Yes, even with the braid jumper ground added, some seem to still be
sensitive to 'parallel' ground of the drive screw, yoke, and rider.
Hi Garey,
With that in mind, I think it'd be a most interesting (and easy) exercise to bridge the
yoke& chassis ground with an ohmmeter set for maximum sensitivity, and then to
observe the (possible) meter deflection from zero as one spun the dial about...or even
let the thing sit for awhile,& check on the resistance from time to time...
Any change in resistance would obviously lead to a "RED 'X'" in the direction
of the grounding of same...
...Sounds too simple to be true, though, doesn't it? Maybe it's that very simplicity that
I was alluding to in my previous post as being the one thing constantly overlooked
because it's either (A) too obvious to notice, or, (B) one of those things that
"...can never go wrong." Hi Hi
~73~ de Eddy VE3CUI - VE3XZ
_______________________________________________
Drakelist mailing list
[email protected]
http://mailman.zerobeat.net/mailman/listinfo/drakelist
