Welcome to my site devoted to amateur radio information, ideas and software.  I really enjoy the opportunities to play weekend electrical engineer and software developer since my day job is neither.

 

What have I done that might be of interest to you?

 

Alpha 84xx Linear Amplifiers

 

Like most hams I really appreciate the myriad of software hams have written and made available for free.  I have contributed to that collection of free software with my Alpha 84xx linear amplifier monitor software. With this software you can monitor much more of what's going on under the hood and make more informed tuning decisions. Software is a great way to add what the manufacturer couldn't put on the front panel.  The monitor even allows a limited degree of remote control as well - such as remote power-on/power-off and selecting what values are displayed on the amp's multimeter LEDs.

 

Users of the monitor who hadn't otherwise seen telemetry from the 8410s were reporting abnormally high thigh plate voltages thinking it was an issue with the monitor.  In my case, telemetry was reporting plate voltage higher than the tubes are rated so it was a major concern for me.  The problem was eventually solved but finding the cause had become a minor obsession.  The troubleshooting process and final resolution are documented on the Plate Voltage Issue page and may be of interest if your 8410 has the original HV metering resistors.

 

 

Due to neighborhood covenants at my former QTH I chose to put my conspicuous antennas in the attic (only an HF-2V went up outside).  Despite having my primary antennas in the attic, I chased DX and awards fairly effectively.  This is typical of many suburban hams so what's different?  I put a pair of orthogonal two-element SteppIRs in my attic and I operated QRO.  With that came motor noise coupling, roof slope and maximum permissible exposure to RF energy issues. 

If this sounds a bit like building a ship in a bottle, it is.  My house was a single-level ranch of about 1150 sq. ft. and the attic is nothing but "W" trusses.  But it was worth it.  No UV damage to the SteppIR fiberglass elements or coax, no storm damage, no water intrusion.  And when QRO I didn't have to worry about corona off the driven element tips causing an attic fire as the elements are totally contained within the fiberglass element tubes.

 

It's about as good as it gets with indoor antennas even though it is still a serious handicap to work out of wood and asphalt-shingled radome.  To see what I did to get two 2-element yagis in a small attic and how they perform, see the Indoor SteppIR Yagis page.

 

 

73,

 

Dan

AE9K