Showing posts with label wattmeter. Show all posts
Showing posts with label wattmeter. Show all posts

Thursday, August 7, 2025

Micronta 51-520A Peak Reading Mods

 This started as a barn find. Over the years, I've had a few of these, and found them to be pretty accurate when calibrated against a known good meter. It's also easy to add a 2000 watt range, but I didn't do it to this one. I decided to modify this one to be a passive peak reading meter, and here's the scoop...



Remote sensor make for easy installation in the shack...



It started as this dirty beast from storage in a barn...


Pin diodes and 1uF cap added...


220k resistor added in place of 20k...


Blue 500k pot installed in 10w position, 100k resistors placed in series with the 100w and 1000w cal pots.



This is the unmodified schematic...


...and this is the schematic with the component changes.


Basic peak reading mods for meters with movements of 1ma or less (200uA or less is better for response).






Tuesday, September 6, 2022

Radio Shack Wattmeter, 3-meter

 A friend gave me this Radio Shack HF wattmeter. It was originally intended for CB. I cleaned, touched up the face, and calibrated it. It's pretty darn accurate on power and SWR on 160-10 meters, and not bad on 6! Adding it to the shack :-)


 


http://www.WB4IUY.net

Tuesday, August 30, 2022

Daiwa CN-101 Repair

 I had an old Daiwa CN-101 HF watt meter kicking around the shack with a bad meter movement. I had thought about tossing it out, but being the pack ratt I am, I tossed it on the shelf. While browsing the for sale bits on QRZ one day, I saw a person with a replacement meter for sale, for one they planned to repair, but never did. I bought it for $10 shipped, stuck it in, and back in service it is. It's not a bad little meter, and was certainly worth saving for $10! Here's a few pics...







http://www.WB4IUY.net

Friday, February 21, 2020

Heathkit HM-102 Watt Meter / SWR Meter

This is probably one of the most popular HF Power & SWR Meters Heathkit ever made. You'll pretty much always find these at every hamfest. Today, they sell for as much as $75, and I've bought some for as little as $10. They're very easy to repair and calibrate, and work nicely on the ham bands from 160 through 10m. I've found them to be fairly accurate (certainly usable) on 6m. Good up to 2000 watts, and can measure SWR with less than 10 watts excitation. I currently have several of these. This is one I bought back around 1991, and use it with my Heathkit HW-101 transceiver.