UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post - Heathkit IM-28 VTVM

ColinTheAmpMan1 · 13th Oct 2019, 3:08 pm

If I were to hazard a guess, I would say that this IM-28 was originally made in the US and wired for 115 VAC including the US-type mains plug. After all, the change from 115 VAC to 230 VAC is effected by changing the tap on the mains transformer primary, not the more common changing of two primaries from parallel to series. This conjecture would conveniently explain the existence of the US-type mains plug and the slightly "bodged" appearance of the "choc-block" connector, which I am sure will not have been original.

As a small query, what is printed at the very top of the meter, right by the place where the "power" light might be? Does it suggest that the meter is a Simpson?
Colin.

13th Oct 2019, 3:08 pm	#16
ColinTheAmpMan1 Octode Join Date: Jan 2012 Location: Wimbledon, London, UK. Posts: 1,465	Re: Heathkit IM-28 VTVM If I were to hazard a guess, I would say that this IM-28 was originally made in the US and wired for 115 VAC including the US-type mains plug. After all, the change from 115 VAC to 230 VAC is effected by changing the tap on the mains transformer primary, not the more common changing of two primaries from parallel to series. This conjecture would conveniently explain the existence of the US-type mains plug and the slightly "bodged" appearance of the "choc-block" connector, which I am sure will not have been original. As a small query, what is printed at the very top of the meter, right by the place where the "power" light might be? Does it suggest that the meter is a Simpson? Colin.