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Old 30th Jan 2018, 1:06 am   #94
John KC0G
Hexode
 
Join Date: Mar 2009
Location: Minneapolis, Minnesota, USA.
Posts: 275
Default Re: The Best GDO Ever Made?

My manual for serial # 7782, copyright 1947, fourth printing 1956, shows 6k8 resistors in series, and R3 as 270k. The drawing is identified as B-1978-Q, and has annotations re. default powers of resistors etc.

The army manual dated January 1959 shows 6k8 resistors in series. This is a nice manual, with lots of repair information.

The manual at:
https://www.pa3esy.nl/meetinstrument...rements59.pdfi s copyright 1947, but has no other dates. It is a later manual as the front cover states that Measurements is a McGraw-Edision Division. The drawing is again identified as B-1978-Q. The last page of the scan is for an errata dated 1960/08/19 which shows that the series resistors were changed to 5k6.

My guess is that the drawings found by Bazz4CQJ were from earlier versions of the instrument. I fully reserve the right to be wrong. The options seem to range from 7k5 single to 6k8 in series to 15k single.

I looked at the pictures at A6EE's blog, and saw one 5k6 resistor in the picture with the acorn valve on top. I am not convinced that it is a single resistor. I opened up the head on my unit. The connection between the two resistors is in mid-air. On mine that joint would not be visible with that particular camera angle.

I hope this helps.

These are really nice GDO's. As others have noted they have a large meter, regulated power supply, go to 400MHz, and have smooth tuning. They are also very nicely put together.

Geoff Arnold wrote a short (2 and 2/3 pages) article on the Measurements 59 for the Aug/Sept 1995 issue (no. 36) of Radio Bygones. He noted that the Model 59, and very similar successor, the Model 159 were produced from the late 1940's to 1985. In a January 1984 price list, the 2-400MHz head plus power supply cost $1819. All three heads plus a power supply cost $3493, and the carrying case another $284. In January 1984 the sterling dollar exchange rate was about $1.40 to the GBP. It fell to a minimum of $1.042 to the GBP on Feb. 26th 1985. These instruments were not cheap! BTW the schematic in the article shows 5k6 resistors in series.

There is a fairly steady stream of these instruments on that well-known auction site here in the USA. They can appear with the title "Magacycle meter" or "Measurements 59" or "Measurements 159". The quality varies enormously. Ideally the power supply and head should have the same serial no. I found one locally a few years ago. It came from an estate and had been treasured. They is hardly a mark on it. It is a keeper

73 John

Last edited by John KC0G; 30th Jan 2018 at 1:21 am. Reason: Additional comment
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