I was licensed in 1961 at the age of 14. My first transmitter was a home built crystal controlled 6L6. After a few months of operating the Novice bands, I earned a General class license and enjoyed the extra privileges. All through the years my main interest has been experimenting and home brewing. I've spent more time on the bench than I have in the operating shack. In the early days there were as many failures as successes. I'm now approaching my retirement years and decided to build a complete home brew station. Anyone who thinks the art of home brewing is lost forever can put that notion to rest. This was about a four year project. The receiver was constructed first. I didn't reinvent the wheel. Both rigs were constructed with proven circuits. Most of the circuits can be found in ARRL publication and on the internet.
The receiver was built around a high-dynamic-range front end featured in recent editions of the ARRL Handbook. Ahead of the mixer is a band pass filter for each amateur band. The receiver is tuned with a parallel load phase lock loop locked to a DDS VFO. The first IF is 9 MHz and limited to a band width of 6 KHz using a crystal filter. The signal is then converted to 455 KHz with a level 10 mixer. Most of the receivers gain is achieved at the second IF. This is also where filters are inserted for additional selectivity. Following the second IF is an AM detector, product detector and various stages of audio processing. I wanted the receiver to look like an old Collins 75A4. You can look at the picture and judge for yourself. The folder that contains my construction notes is about two inches thick.
After a couple months of rest I started the transmitter. The transmitter, like the receiver, covers all amateur bands. Although not as complex as the receiver, it came with its own unique problemshigh current, high power, heat and high priced transistors. The architecture of the transmitter is similar to the receiver. I did however, elect to use a serial load PLL chip with this design. The price I had to pay was a few extra weeks learning how to program a micro-controller to read the band switch. Many thanks to my son-in-law for his help. After blowing the first set of final transistors (and much cursing) I equipped the power supply with current limiting and over voltage protection. The transmitter will also trip if the SWR gets too high. The final transistors (MRF-422) and power supply are rated for about 300 watts. Both enclosures are made of steel. I found a supplier that sells small quantities and will even cut them at no extra cost. Front panels were decaled with Dry Transfers and the paint came from Home Depot.
When I tell people the station here is all home brew, I get the feeling they think it's an aluminum box with a 9 volt battery. That's why I decided to post this bio on QRZ. A picture is worth a thousand words.
Last modified: 2011-01-21 21:18:58, 2924 bytes cached
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