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Reviews For: Sprague Tel-Ohmike TO-5 Capacitor Analyzer

Category: Tools & Test Equipment for the amateur radio work bench

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Review Summary For : Sprague Tel-Ohmike TO-5 Capacitor Analyzer
Reviews: 1MSRP: 83.90 in 1960.
Capacitor bridge with range of 10 pF-2000uF, Insulation Resistance tester 100 Meg-20,000 MegOhms, and Transformer Turns Ratio Bridge 1:1-100:1. Uses Magic Eye tube as an indicator for capacitance and turns ratio.
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
N1BEC Rating: 2007-11-11
Excellent performance for an analog meter! Time Owned: more than 12 months.
The TO-5 is one heck of a meter, it's just as useful now as it was when it was new!
The tube lineup is a 6C4, 1619, and a 1629 Magic Eye Tube.
After restoration (more on that shortly!), the dial was almost dead nuts on over the entire range of capacitance. You can measure ESR/power factor with it, too. What a joy to work with such a fine piece of equipment!
The MegOhms scale works well and has its uses: You can measure the actual capacitor leakage under rated voltage, measure insulation resistance, and use it (with an appropriate series resistor!) to reform electrolytic caps.
I've not used it yet to measure turns ratio.
This model fixed a lot of the problems with the TO-4:
-The wiring isn't brittle, so that's a major hassle you don't have to go through.
-The internal chassis that holds the tubes is fixed to the front cover with a cross brace, so it won't flop around like the TO-4's does.
-The bypass capacitors aren't leaky like the ones in the TO-4... I've left all the "Black Beauties" there, and only swapped out the electrolytics.
-Messy wiring is partially replaced by a real circuit board.
-The unit comes out of the case (and goes back in!) much easier than with the TO-4.
One thing that's endemic to the TO-4's, -5's, and -6's is the leaky reference caps: The 2 uF "gimmick" cap consists of two 1 uF paper foil caps allegedly matched. They are leaky as a sieve, and nowhere near accurate anymore.
The TO-5's 2 uF cap actually measured over 4 uF on my Sencore Z meter!
The two highest ranges (4 & 5) use the 2 uF cap as a reference.
Range 3 uses the .02 uF cap as a reference.
It is not necessary to replace the range 1 & 2 caps.
Once you replace the two reference caps, check the other caps for leakage. Replace the two electrolytics, pull and test the tubes, clean all pots, switches, and tube sockets. Treat them with DeOxit afterwards.
Do yourself a favor and install a CL-60 inrush current protector (RF Parts Co.) to protect the filaments when you turn the set on.
Lay in a supply of tubes, and you'll have a test instrument that will last you a lifetime, and that you can hand down to the next person!
If you need a manual, go to the BAMA site, and download it. Make sure you also download the calibration guide by David K.
Typical Ebay prices are a C note or more, I lucked out and picked this one up for only $60 at a local Hamfest.
They are well worth whatever you have to pay for them!

73's -Tom N1BEC/7