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Reviews For: Heathkit HO-10 Monitor Scope

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

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Review Summary For : Heathkit HO-10 Monitor Scope
Reviews: 1MSRP: 59.95 (1962)
CRT based signal monitoring unit from the early 1960s. A 2 inch cathode ray tube (CRT) gives a visual representation of several user-selectable transmit (and limited receive) signal tests. Probably the most useful (and easiest to set up) test is to show the transmitted waveform (best way to detect flat-topping).
Product is not in production
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WB5AGF Rating: 2015-09-20
A Half-Century After Its Introduction - Still Useful Time Owned: more than 12 months.


I've gotten back on the HF bands after an absence of almost 10 years and in doing so that included getting my old Heathkit HO-10 Monitor Scope back doing what it's supposed to do (i.e. monitor my transmitted signal).

Originally the old HO-10 turned-up-and-played (well at first it 'ate' a fuse but then a bit of time using a Variac auto-transformer and the caps reformed) but after about three weeks it suddenly lost its horizontal sweep. Some rather suspicious symptoms pointed to the coupling capacitor between the horizontal sweep generator and sweep amplifier as being the culprit and changing that out fixed the problem.

(and now for my review ....)

For being a device designed and sold in the early 1960s the HeathKit HO-10 Monitor Scope is still a remarkably useful item to have around an HF Amateur Radio Station. Any ham used to being able to visually monitor their signal is never quite happy without a glowing CRT to glance at during a transmission.

I bought my HO-10 from my friend W5AEQ (SK) during the summer of 1981 and it has been a part of my station ever since.

Although the HO-10, as originally designed, has several additional capabilities (two-tone test generator, in addition to monitoring one's transmitted signal ... that is all that I have ever used mine for (indeed I removed all the tubes not needed for the transmitted RF monitoring function years ago to cut down on heat production and reduce the strain on the power transformer) and so that's all that I can report on.

As part of my getting-back-on-HF campaign I bought a new HF radio and, as part of learning all the adjustments-and-settings, I used the HO-10, while transmitting into a dummy load, to confirm that the transmitted SSB signal had nice, clean, peaks, with no sign of clipping. The ability to monitor one's RF is especially important when any form of voice signal processing is used (my high-pitched voice is very 'peaky' and some form of processing is needed to bring up average power to respectable levels).

The HO-10 is not what I'd call a piece of precision test equipment but it's small, fits right amongst one's HF radio equipment, and it does the job of monitoring the transmitted signal just fine.

(replaced by)
Heath replaced the HO-10 with the SB-610 (still basically the same tube design) in the mid-1960s and then later the mostly-transistorized SB-614 replaced them both. (Note: During this period Heath produced another piece of monitoring equipment that looks almost the same but it had a different purpose. The HO-13 was the same physical size as the HO-10 but it was a 'panoramic adapter', a poor-man's spectrum analyzer, and it coupled into a receiver's IF to give a limited visual display of signals above-and-below where the receiver was tuned to. From a distance the HO-13 can be most easily differentiated from a HO-10 by the fact that the HO-13 has a CRT with a P7 yellow phosphor, for slow brightness decay, whereas the HO-10 has the more common green, fast persistance, phosphor.)

- Paul, WB5AGF

PS - A note of caution to newer hams without experience with tube equipment - especially those using cathode ray tubes (CRTs). The little HO-10 generates over a thousand Volts to run the 3 inch CRT - It may not have enough current to kill a healthy person but it can still deliver a painful jolt. Take care when working on this equipment.