After putting up my efhw antenna, I wanted to test a few other bands. I’ve never done much with 80 meters, so I figured I’d give it a try with a raspberry pi WSPR transmitter. To do that, I needed a filter for 80 meters to suppress the harmonics from the square wave from the raspberry pi. I found a good video by ZL2CTM showing his experiments with an 80 meter bandpass filter.
I’ve been wanting to get back into radio stuff for a while now, but the only antenna that I have up now is a 40 meter dipole. I’ve been wanting to put together a decent multi-band antenna for a long time and finally settled on an end fed half wave antenna. An end fed half wave antenna, or efhw, is a variation of a half wave dipole, but it is fed from one end.
While cleaning out some old boxes in a shed, I found “The World’s Smallest Color Bar Generator” by Sencore. It was still in the box with the original receipt and manual, but it was a little damp and smelly. I figured it would be fun to see if it still worked, and if not, see if I could fix it. The leads were coiled up in a little tube compartment in the back, but when I tried to pull them out, they just started disintegrating.
Wow. Its been over a year since I last posted anything. Over the past two years, I’ve been working as the project manager for a large software/infrastructure implementation, so that has taken up most of my time. That project started a month or two before COVID hit and we basically powered through the entire pandemic with our primary team on-site for all but a few weeks when our state issued a shelter in place order.
I guess its my turn to jump on the #septandy bandwagon. #septandy is where retro computing bloggers and youtubers take a look at tandy gear in the month of September. I picked up a tandy color computer 2 with a tandy tape drive on ebay a while back and hadn’t gotten around to testing it out. The coco2 only has RF out and the only RF device I had available was an old VCR.
After building Ben Eater’s 6502 computer, I wanted to try my hand at my own version. I wanted to utilize the full 32k of ram and use a real monitor as the display. I started with a W65C02 processor and an AT28C16 eeprom. I filled the eeprom with nop instructions and set the eeprom to the top of the memory map. I’m using the same slow clock module and Arduino sketch from Ben Eater to view the address and data buses in real time.