Posted	Category
	Restoring Aluminum Knobs  I've always thought that knurled aluminum knobs were a high-class option for radio gear, and while they are more durable than plastic they do accumulate tarnish, corrosion, and grunge from dirty fingers over the years and start to look poor.   Fortunately it is easy to restore them to a new attractive appearance using a bead blaster. Mine is a Harbor Freight floor-standing...  READ MORE	ranickels 04/29/2021	Technical
	Replacing C-frame fans  It's not often that you can buy a replacement part for a vintage transmitter or amplifier off the shelf at the home improvement store, but this is one example.   And since it's not a perfect drop-in replacement, here's now I adapted a new Broan-Nutone BP-27 bathroom-kitchen exhaust replacement fan to fit into a Johnson Desk Kilowatt.These small shaded-pole "C frame...  READ MORE	ranickels 04/23/2021	Technical
	Restoring the B&W 850 Plate Inductor The B&W 850 is a kilowatt-rated tank assembly that was used in the company's linear amplifiers and sold as a component for many years.  Unfortunately most of the plastics available were not capable of surviving for 50-70 years and thus have deteriorated to the point they no longer support the coil turns properly and must be repaired.    Here's a typical example from...  READ MORE	ranickels 02/28/2021	Technical
	AN/GRC-9 Bias Battery replacement The Korean-war vintage AN/GRC-9 is one of the most useful and fun military field radios for ham use, as with AM and CW modes and 2-12 MHz coverage and a VFO it's all ready to go on several ham bands.    The battery tube superhet receiver is also power-friendly and sensitive and stable enough to copy CW and SSB but has one annoying flaw - the 4 volt bias battery used by the audio...  READ MORE	ranickels 01/03/2021	Technical
	Beware of the LED Noisemaker! Halogen type MR-16 lamps are commonly used in track lights and other spot lighting applications so what would be cooler than to drop in LED replacements!   A lot, as it turns out.   The LED replacements are HORRIBLE RFI emitters that totally trashed several ham bands when I unknowingly installed them.Halogen spot lights are 12 volt devices so it's long been common prac...  READ MORE	ranickels 01/02/2021	Technical
	why 50 ohms?  Why do we use 50 ohm cables?    If you're like most hams the answer is:  "I dunno!"In fact, it's a compromise (like most things in life) - between lowest loss when handling power and voltage breakdown, as Belden engineer Steve Lampen explains hereA pdf copy can be found below as well.   And now you know!...  READ MORE	ranickels 09/06/2020	Technical
	Bias control of Class E amplfiers Micro SDR innovator Guido PE1NNZ has implemented polar modulation using an Arduino MCU and a class E PA.   For more informartion on this fascinating project, join the discussion group at https://groups.io/g/ucxInitially, Guido's design implemented the polar or EER modulation scheme using modifications to the QCX CW transceiver hardware in the traditional way as described by Leonard K...  READ MORE	ranickels 06/20/2020	Technical
	Class E Notes  There is a lot of misunderstanding about how a Class E amplifier works.     As the result of studying the literature and experimenting, I thought I'd share what I have learned over the past several years.   Below is an example of a test amplifier I used to optimize my 2 watt wspr transmitter boards.   It can be visualized as two circuits - the...  READ MORE	ranickels 06/06/2020	Technical
	Communications Associates Inc. SSB-125 marine radiotelephone What can I say, I like oddball radios!    There was already a different version of this CAI SSB-125 on my shelf but it had the remote control head, and this one was cheap, well under $100 including shipping, and I'm easily amused.   VIDEO DEMO HERECommunications Associates Inc. was a supplier of commercial, military, and marine radios based in Huntington Station, ...  READ MORE	ranickels 05/14/2020	Technical
	"B" Bench update  Like most of those reading this, I've upgraded and added to my test equipment inventory over the years, starting with the Heathkit VTVM I built when I was 15 or so.   There's no "right" piece of equipment, just personal preferences, and while I'd be the first to say my work habits are anything but "right" they are what they are, and I'm old enoug...  READ MORE	ranickels 02/03/2020	Technical