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Reviews For: Struthers AN/URM-120A

Category: SWR & Wattmeters & Dummy Loads

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Review Summary For : Struthers AN/URM-120A
Reviews: 11MSRP: 1,700 (!!) new, 50-150 used
Description:
US Military RF wattmeter, 2-1000 MHz, various power ranges
Product is in production
More Info: http://
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
00114.5
KE4MOB Rating: 2003-02-22
Right up there with the Bird 43 at 1/3 the price! Time Owned: 0 to 3 months.
I think this thing is one of the best kept secrets in ham radio. The AN/URM-120 was produced for the US military by various suppliers, and is now being retired from service and being replaced with more modern equipment. The meter uses three slugs to cover 2-30, 25-250, and 200-1000 Mhz. Each slug has a knob on the top with four selections which allows for various power levels to be selected. On the 2-30 MHz slug 50, 100, 500, and 1000 watts are available. On the 25-250 and 200-1000 Mhz slugs 10, 50, 100, and 500 watts are available.

To operate, the proper slug is selected, and two latches on the meter housing are released. The entire top half of the meter comes off, and the slug is inserted into the line section. A small RG-174 jumper connects the meter to a jack on the side of the slug. The cover is then latched, and the measurement made. Like the Bird, if reflected power is to be measured, the slug is rotated 180 degrees (so that the arrow points to the transmitter rather than the antenna). Drawbacks: it's not as easy as using a Bird--but when you figure all the various Bird slugs that you would have to buy to make up for the capability of AN/URM-120, it's more than a fair tradeoff (and no, Bird slugs won't work in it). The slugs are mechanically fragile (especially the end that houses the sampling components) so don't let them roll around in the car. Other than that, I have found it to be built extremely well. There seems to be at least two variations: one with a scale for measuring VSWR and one without. Also, there are several different connector arrangements: the two most prevalent are 2 SO-239s and 1 Male N--1 Female N. So if you buy one over the internet, etc. you may want to verify the types of connectors that come with it. I would also look for one with the military calibration stickers still in place. It's no guarantee, but at least you know when it was last calibrated!! All in all, a very useful piece of equipment courtesy of Uncle Sam. His obsolete equipment is our treasure chest!!