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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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23rd Oct 2006, 1:11 pm | #1 |
Pentode
Join Date: Jul 2006
Location: Sidcup, Greater London, UK.
Posts: 122
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1941 AM AVO Model D (Model 40 Variant).
I've just aquired an Air Ministry AVO model 40 dated 1941 serial No. D.3642-1241 it uses just one 1.5 volt battery.
As can be seen from the attached photos it has a rotary switch mraked K=1 & K=2 in place of the usual devide by 2 push button and only 2 ohms ranges. My question is, should it have the more usual pull up and turn Q knob as mine has no track or slider see photo just a knob jammed into the hole in top panel, wrong type of knob than normal, no metal spindle. The instruction plate is missing from rear of case, this might have answered my query. Anyone have a scan of this plate you can let me have?. Thanks for your help. Trevor |
23rd Oct 2006, 6:07 pm | #2 |
Rest in Peace
Join Date: Nov 2004
Location: Antwerp, Belgium
Posts: 345
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Re: 1941 AM AVO 40 Help/advice wanted
Okay; what you have is a Model D, a Model 40 variant introduced specifically for the Air Ministry during WWII. What you have is "right". The high ohms range was deleted, along with the need for a 9 volt (= 2 x 4.5 volt) battery, and the Q knob switch and pot. The DIV 2 button was replaced by a K=1/K=2 switch (which served the same function), and the voltage & current ranges were changed from a 12 base to a 15/7.5 base. The basic movement sensitivity was increased from 3 mA to 2.5 mA. Yours appears to be an early model, and may still have the 3mA movement. The important thing to remember is that the two ohms ranges require the "undivided" K=2 setting. If you send me a PM with your e-mail address, I'll send you a scan of the instruction plate.
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