PROJECTS IN PROCESS OR IN PLANNING:
♦ I finished building the 6AG7-6AG7-6L6 xmtr, based on an article in the 1947 “West Coast Handbook,” which explains the use of a BC-221 as the VFO for such a transmitter. The original article used 6AC7 tubes which are low gain and I used the high gain 6AG7’s instead. I installed cathode resistors in these so that they don’t run at their maximum output and to reduce stress. I bought an old “Bud Box” at the last Raleigh hamfest for $3, stripped out the rusted and useless components in it, made a new panel and chassis and repainted it. Intent is to create an “old” look. The power will be sourced from an external power supply. The output tank uses a rotary inductor with turns counter. I also have a Collins PTO to use as a potential VFO. I will build an interface between my solid-state keyer and the xmtr cathode keying circuits. Probably a 2N2222A or 2N3904 and an IRF510 design. I plan to build a 6080 cathode modulator to generate some low-level AM, and then use this little xmtr to drive linear amp. I might also use a MOSFET instead of the 6080…still thinking it over…might use a carbon telephone microphone rather than an electret or condensor mike…not sure.
♦ I acquired a Harvey-Wells TBS-50 cabinet with ruined internal components which I intend to rebuild into an 807 nostalgia transmitter. I have all the parts – just need to build it.
♦ At the Raleigh hamfest I acquired an ancient Boonton FM deviation meter in a large, very nice aluminum case, with a panel about 12″ wide by 17″ high. It was not restorable but the cabinet is excellent – needed paint only. I’ve made a new panel and chassis for the 813’s, and modified the back of the cabinet to accommodate an AC interlock, fuse, B+, VFO-in and ANT-out sockets. I think the 807 xmtr will drive the 813’s satisfactorily. If necessary I can wind a toroidal step-up xfmr to boost the 807 output voltage a bit.
♦ My 1972 Heath SWR/Power meter needs to be rebuilt and is on the bench awaiting its turn. I’ll use it with the old-style equipment I’m building or maybe with all the equipment.
♦ The 40/30 meter solid state regenerative receiver works well on 40m and just adequately on 30m – the 30m bandspread is inadequate. I have some ideas for a better regenerative control and some other circuitry.
♦ I bought a pristine “Bud Box” at the hamfest for $5 and it contains a 70 year-old professionally built heterodyne frequency meter including an excellent variable cap with geared drive and a beautiful brass dial. It will make a perfect tube-based regenerative receiver containing a 6J5 regen stage feeding a 6SN7 first and second audio stage and a 6V6 or 6F6 final audio stage. The 6J5 is 1/2 of a 6SN7. A voltage regulator tube is included. The frequency meter contains a built-in 1000/100kc 6SK7 crystal frequency standard which will be helpful in finding band edges when receiving. The regen stage will be fed from an outboard RF preselector/amplifier I plan to build. January 2019 update: I just stripped out all the wiring, added a new, three-wire AC cord, fuse, a varistor in the AC line to slow the start-up surge and rebuilt the power supply. The circuit of the crystal frequency standard was traced out and that was put back in service It seems rather stable after warm-up. Next I will wind the coil for the regen tube and create that…I need to find an audio choke first. I have all the parts to complete this work except the audio choke but I can fake that – just need time to do it. Being retired keeps me very busy! I will add photos of this project later.
♦ I have parts for a NE602/612 DC receiver which will run in the 1 – 3mc band for stability and be crystal-converted to ham bands. Actually, I’ll use ceramic resonators, not crystals. I’m not sure when or if I will get to this one.
♦ I like to play with old stuff – tubes, mainly. But I like analog solid-state as well. I don’t know enough about digital circuitry. I have a nifty 400vdc + fils power supply on a small chassis that was in the Boonton FM meter and it has two empty ceramic sockets. I’ve added an AC interface/filter and a power switch and am it will make a nice stand-alone power supply for the little 6L6 transmitter..
♦ I’m thinking of a Class E MOSFET transmitter fed by an existing VFO…perhaps the Collins PTO which I’m thinking of converting to solid state so that I have one that could be used when the power goes out.
♦ I want to build an audio oscillator.
♦ I want to build an RF/Audio signal tracer
♦ I should recalibrate the LM-8 and a BC-221 that works but which is stored.
♦ I have an old D-104 mike that looks cool and which I want to use in my little xmtr but which has to be checked out first – I don’t know if it works.
♦ I have parts to build a stand-alone crystal calibrator and a field strength meter in the same cabinet. Of course, the BC-221’s and LM-8 can be used for the same purpose…I have too much stuff.
♦ I just bought some of the $10 Chinese frequency counters on eBay and need to figure out how to incorporate them into my LM/BC units, my Regen receiver and the Collins PTO VFO.