[Milsurplus] R-720 AN/URH-2 ??

[Hubert Miller]

That's really interesting, Nick. I hope the owner feels that it deserves to survive, somehow, as it may well be the last of its kind
on this planet.
I wonder what it used for an antenna? Loop antenna, I suppose, most likely, as with other LF and MF frequency selective
voltmeters?
-Hue

>Based on the use and the front panel markings here's what I think - there are multiple running-time counters which read in 1/1000's of an hour. A counter was turned on when the relative signal strength was between limits, so the net result is you could tell what fraction of the total time that a signal was at a particular level. It is hard to tell from the photo but it looks like the counters might be
0-20dB, 20-30dB, 30-40dB, 40-50dB, 50-60dB, 60-80dB, over 80dB, total time

Here's what I got from an engineer who used this receiver/recorder -
"I remember that receiver because we used it at VLF monitoring stations in the Pacific area and it was used with Esterline Angus chart recorders. That was 60 years ago so I remember little more. I was sent all over the Pacific area to establish sites for the monitoring stations. This was all under the direction of Jack Pierce of Harvard."
"The monitoring stations were established to determine the VLF signal strengths in the Pacific area. This was necessary to determine the feasibly of communicating with submarines and if the signal strength was adequate for underwater navigation. I set up stations at Shemya Alaska, Hawaii, Fiji, New Zealand, Australia, Jakarta, Philippines, Japan and Wake Island."

Nick England K4NYW
www.navy-radio.com<https://nam04.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.navy-radio.com&data=02%7C01%7C%7C70f397749c8b435e54bb08d5b05c50e4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636608834978800747&sdata=8aBfbjLX3JBgD5W%2BGtlM2lPkdtWr9ThOI0DqccHs3K4%3D&reserved=0>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/milsurplus/attachments/20180502/6058ce3a/attachment-0001.html>