jbn@glacier.STANFORD.EDU (John B. Nagle) (01/02/89)
Where can I get a low-cost RF wattmeter good for 1.2GHz? The power range
required is 50mW to 5W or so at 50 ohms. Either an inline or terminating type
wattmeter is acceptable; an SWR capability would be nice but is not essential.
Precision required is very modest.
It's easy to find wattmeters for low bands, but it's hard for UHF. Any
ideas?
John Nagle
KA2XXF (part 5 experimental)larry@kitty.UUCP (Larry Lippman) (01/02/89)
In article <17960@glacier.STANFORD.EDU>, jbn@glacier.STANFORD.EDU (John B. Nagle) writes: > Where can I get a low-cost RF wattmeter good for 1.2GHz? The power range > required is 50mW to 5W or so at 50 ohms. Either an inline or terminating type > wattmeter is acceptable; an SWR capability would be nice but is not essential. > Precision required is very modest. > > It's easy to find wattmeters for low bands, but it's hard for UHF. Any > ideas? While it won't give you great resolution at power levels of 50 mW, the cheapest off-the-shelf solution is to get some high frequency elements for a Bird 43. You can get 1, 2.5 and 5 watt elements (P/N's 1K, 2.5K and 5K, respectively) that cover 1.1 to 1.8 GHz. These elements will also work with a Bird 4381 or 4391. You can go the Hewlett-Packard route. Now before you complain about this not being "low cost", bear in mind that there is a lot of H-P equipment in labs that you could possibly borrow. Furthermore, H-P power meters (of the analog variety, at least) are pretty common and inexpensive on the surplus market. An H-P 432A or 432B power meter with 478A thermistor mount will give you 10 mW full scale up to 10 GHz. All you need is a coaxial power divider to bring the thermistor mount into range. An H-P 435A or 436A with 8481H or 8482 thermocouple mount will read directly to 3 watts. I personally have a 435A with 8481H, would recommend that as the best of all of the above for your application (unless you have access to the 436A, which has a digital readout). If you really need to go to 5 W, a power divider is trivial. <> Larry Lippman @ Recognition Research Corp., Clarence, New York <> UUCP: {allegra|ames|boulder|decvax|rutgers|watmath}!sunybcs!kitty!larry <> VOICE: 716/688-1231 {att|hplabs|mtune|utzoo|uunet}!/ <> FAX: 716/741-9635 {G1,G2,G3 modes} "Have you hugged your cat today?"
john@wa3wbu.UUCP (John Gayman) (01/02/89)
In article <17960@glacier.STANFORD.EDU>, jbn@glacier.STANFORD.EDU (John B. Nagle) writes: > > Where can I get a low-cost RF wattmeter good for 1.2GHz? The power range > required is 50mW to 5W or so at 50 ohms. Either an inline or terminating type > wattmeter is acceptable; an SWR capability would be nice but is not essential. > Precision required is very modest. > Would most of your measurements be closer to 5 watts or 50 mW ? Bird Electronics makes a variety of elements for thier Model-43 Thruline wattmeter covering the 23cm band. I have three of them here that I use for 1.2Ghz. They are: 5K (1.1-1.8 Ghz, 5W), 433-103 (1.1-1.8 Ghz, 50W), and an old military CU-1677/URM-167 (1.0-1.8 Ghz 25W). I have also seen some 2.4 Ghz slugs (10W & 25W) that they manufacture. And..... in my Model-43 manual they list slugs covering 1.1-1.8 Ghz with 1W, 2.5W, 5W, 10W and 25W full scale. I'll admit that Bird may not actually be the "least expensive" wattmeter you can find. But its hard to beat its flexibility for $170. In case your interested, Bird's number is 216-248-1200. Good luck. 73, John -- John Gayman, WA3WBU | UUCP: uunet!wa3wbu!john 1869 Valley Rd. | ARPA: john@wa3wbu.uu.net Marysville, PA 17053 | Packet: WA3WBU @ AK3P