Dale H. Cook ) writes:
On Tue, 18 Jan 2005 06:08:14 GMT, "COLIN LAMB"
wrote:

Years ago, I decided to convert one of my Millen tube jobs to a solid state
one

When I got done, the 2 highest bands were off calibration.

That's because the inter-electrode capacitance of the tube is part of
the tuned circuit.

I don't know if the poster was referring to it, but QST ran an article
in a December issue, I think 1972 but it might have been 1971, by someone
from Millen about their work on making a solid state version.

They used the same coil set and tuning capacitor, though I don't recall
if they changed the dial.

It was not a conversion article, not a construction article, but about
what they needed to do in order for the solid state version to put out
a flat output, with few false dips. It was interesting to read, at the
time.

Michael VE2BVW

"I don't know if the poster was referring to it, but QST ran an article in a
December issue, I think 1972 but it might have been 1971, by someone from
Millen about their work on making a solid state version."

You get a gold star on the memory test. It was December of 1972. I think
it was titled "Anatomy of a Grid Dip Meter", and it was written by the chief
engineer at Millen, who had led the conversion team. It is a worthwhile
read for anyone who thinks of converting an rf device to solid state. In
particular, the simple rf choke became a substantial barrier. The end
result was multiple rf chokes and ferrite beades placed in just the right
order to work at all frequencies. I recall Millen worked for days on the
"simple" task of creating something that would work as an rf choke on all
frequencies.

Colin K7FM



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Is there anyone left who is familiar with calibration of a Millen 90651 grid
dip meter? ....

The Millen grid dipper was never a calibrated ,or accurate device, to
get an accurate reading ,tune a receiver to the desired frequency and
set the dipper to the receiver ,You will be anble to get "in the ball
park" Good Luck W4PQW

Hmmmn. Never calibrated?

I have a chart from "James Millen Mfg. Co., Inc" dated 1-31-50 and
titled "Calibration of low frequency inductors for James Millen
#90651 or #90661 Grid Dip Meter".

--Myron, W0PBV.
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

The Millen grid dipper was never a calibrated ,or accurate device, to
get an accurate reading ,tune a receiver to the desired frequency and
set the dipper to the receiver ,You will be anble to get "in the ball
park" Good Luck W4PQW

Hmmmn. Never calibrated?

I bought my 90651 new in 1955. It was
considered the best GDO *because* of
its good calibration. The accuracy was
very good for a time when frequency
counters were laboratory curiosities.

73, John - K6QQ