The start of my collection.
This Russian copy of an Unigor was my first analog multimeter and given to me by my dear friend PA0VIC. It was stored in a leaky barn for 25 years. The foam in the metal box was gone and so was the paint.
The Philips meters are very nice. The PM2505 is an active meter, You can see it as a DMM but with an analoge meter instead of a digital readout. It is powered by two 9V batteries. It has auto polarity. The cute little meter inside the main meter point at plus or minus. And shows if the batteries need replacement. I think a lot of users had to learn the hard way it was not a good idea to leave it powered. (most analoge meters in the years before this where passive) It is 10M and can do 1uA full scale.
The other one is a PM2502, a normal analoge meter.
The PM2505 manual:
One of my AVO 8’s. This one is a 1959 AVO-8 mkII. It has a 2500V range. The probes are stored on the top. The battery used for low ohm resistance measurement is a 15V Eveready No.411 or a BLR121. Duracell sells one as MN154. Other names are: 10F20, NEDA 208, ANSI 208, BA 331/U, Mallory M121, Burgess U10, Burgess K10, RCA VS082.
The other resistance ranges use a 1,5V D-cell.
http://www.pa4tim.nl/?p=2010 How to make a replacement if you can not find the 15V battery.
Source: PP Munro:
In 1936 AVO introduced the model 7 as an improvement of their 36 range Universal Avometer. The improvement was current through the meter. “Only” 2mA for a full scale reading instead of 6mA. Als de devide by 2 knob is pressed that current drops and this made it more sensitive.
Model 7 was made for radio work. The original patent was ended and new firms like Simpson and Taylor also started to make multimeters. Those hade a 50mA sensitivity that gave a FSD of 20kohm/V. The only 20k/V meter Avo made was the Avominor. It was aimed at television repair.
In 1939 the model 36 AVO was replaced by the model 40. It used the automatic cut-out from the AVO7 but it used the 0-120 scale, sensitivity and ranges of the model 36. It was an universal meter.
AVO made their first 20 Kohm/V in 1947. It was a full-size meter. It was not a succes for civil use. In 1951 it was replaced by the famous model 8. For export they made a model 9. Thougether with the exportmodels 10, 14, 15, 16, 20 en EA 113, only the last model was a minor succes in England.
Model 8MKV was made according the NATO standards but also usable for civil use. It was succeded by the Mk VI and MkVII. It stayed in production until 2009. The main reason was the army regulations. It was very expensive. AVO is now owned by Megger.
A cute multimeter from the US army made during WW2.
This is the Simpson 260-6, the US alternative for the AVO-8. A very nice build and practical meter. It featured a single function/range knob. “normal” batteries (9V and a D-cell)
A Japanese multimeter, the Kamoden 360. Probably from the 70’s