The local ham club I am a member of was handed several decommissioned or defective K-band police radar heads similar to the one shown on the right. We knew these contain a gunnplexer and can potentially carry Wideband FM (WBFM) radio contacts. This would allow our club to add a band to the ARRL June VHF QSO Party. At the last club meeting, I raised my hand when it came to who would try to put these 24 GHz police radar heads on the air. So here is my report on how things are progressing.
I have built or repaired several VHF and UHF RF power amplifiers in my ham career. Some were solid state (transistor-based), some had power vacuum tubes (valves). It has been a mixed results experience so far. Lately, I have been receiving comments from some other hams who claim that the dual-3CX100A5 tube 1296MHz amplifier I am putting together is outdated and that I should switch to power transistors in my design. No doubt that the transistors offer some advantage over tubes, but they also have drawbacks. The following is my view of the pros and cons of both technologies.
Just to give you a heads up, I just ordered a NEScaf CW audio filter from the New England QRP Club . I will be using it with the FT-817ND. I figure it will be more helpful than the optional Yaesu or W4RT CW Filter module, and at a small fraction of the cost. $31 for a full-featured switched-capacitor audio filter kit is a very good deal. It is not an IF filter, but it will sure help a lot on the CW copy. Its variable bandwidth and center frequency will be a plus. I intend to carry it around when going portable-QRP.
Update (30/08/2011): Just received the kit yesterday and have started assembling it. Instructions are very clear. It total, it should take me about 90 minutes of assembly time before firing it up. I will report back on the unit as soon as it is assembled. So stay tuned!
Update (31/08/2011): I managed to find time to wrap up the assembly process and power up the NEScaf board. Here are my first comments on the assembly process and the filter operation.
The last time I escalated King Mountain for my mini VHF expedition, I brought along a 12 Volt, 7 Ah, sealed lead-acid battery to power up my FT-817ND radio. That battery weighs a hefty 6 pounds (2.7Kg). Luckily, we only had less than 30 minutes of hiking to reach the top of the mountain. Besides, I use that battery in my home alarm system, so I had to find a better mountain-top power solution for my next portable radio expedition.
While reading the FT-817 Yahoo! group, I learned about this 12V,6800 mAh Rechargeable Li-ion Battery sold on eBay for $19 (U.S.), including charger and shipping. I elected to order one from eBay seller "sinedya" directly from China. This is a super-power seller, with more than 208,000 feedback entries!