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Reviews (9)
09 Nov, 2016
Not the best but good value for the price
There are certainly many much better quality phone plugs on the market but they are all a lot more expensive. These are good for general purpose use and a very good value for the money. Recommended unless you need the best.
14 Mar, 2017
Excellent meter IF refurbished & upgraded
2 of 2 found this helpful This was one of Heathkit's better instruments. It is stable and (if properly calibrated) quite accurate. It does suffer from two flaws that should always be corrected when a unit is upgraded. These are use of a battery to power the ohms circuit and use of a 6AL5 tube as the ac volts measurement rectifier.
Upgrading should power the ohms function internally, with no need for a battery. It should also replace the 6AL5 tube with two silicon diode rectifiers.
When these upgrades are done, and the unit is fully tested and calibrated on ALL FUNCTIONS AND RANGES, it is an excellent instrument.
05 Feb, 2017
GOOD INSTRUMENT...IF
The Heathkit IM-11 was, in its day, a good little general purpose vacuum tube voltmeter. It did, however, suffer from three design drawbacks:
1. Use of a dry cell battery to power the ohms function
2. Use of a dual-diode vacuum tube in the ac volts function
3. Lack of separate meter scales for the two lowest ac volts ranges
The first drawback caused many instruments to suffer internal damage due to a leaking battery. A weak battery also often caused inaccurate ohms measurement. Both of these problems are solved by modifying the instrument to eliminate the ohms battery.
The second drawback caused zero drift on the low ac volts ranges and the need for an internal "ac balance" adjustment. Both these problems are eliminated by replacing the dual-diode vacuum tube with two silicon rectifier diodes, a design change that has been possible since at least the early 1960s.
The third drawback causes the lowest ac volts ranges to be inaccurate by as much as 15% or more. No modification can cure this problem, but it is normally not an issue for most users, as the two lowest ac ranges are seldom used in most situations.
Any IM-11 that has been modified and upgraded to eliminate need for an ohms battery and has had the dual-diode tube replaced by two silicon diodes is an excellent value. Without these modifications the instrument is only of mediocre value.