|Finally, after about a year of
procrastinating, I've started work on the 1935 station.
Electrically, the receiver is finished, and the power supply for the
transmitter is 90% done. The receiver is a 3 tube, 2.5V filament
Super Gainer, using the #57 mixer, #56 Local Oscillator and #53
regenerative detector/ audio amp.
The receiver is electrically finished except the headphone jack needs installed yet and front panel needs painted.
Here is a top-rear view. The oscillator is on the left, mixer on the right, detector is bottom center.
The receiver does a fine job on 80 meters. I have a coil set wound for 80 and 40 at this time. Was able to copy CW quite strong on 80M, and listened to some SSB on 40. AM performance is pretty good as well, although the most recent evening there was little activity on 75. Listened to that amateur broadcaster on 3890 and received it well. That QRM generator at least is a good test of a new receiver but I wont interject any other feelings regardng his operation beyond what I've already said.
The transmitter for the station I've decided will consist of a #47 crystal oscillator followed by either a 46 or a 841 or an 801. I still havent decided on the tube as yet. Any one will be sufficient as an exciter for a 203A class tube. The 203A will be the last part I build, if I even build it. I'm leaning towards an 801 and plate modulating it with a pair of 46's. The power supply is almost finished, it's built on a wood breadboard and will be the bottom section of a homebrew wood tabletop rack. Here is a photo of the power supply.
Power Supply for the transmitter
You will notice a LOT of unused space on the right of the board. This will be where the high voltage will go if I add the 203A stage. If I do add it, I will run about 1000 volts on the plate. The low voltage supply delivers about 400VDC, and will run the 801 at about 20 watts DC input. I do have a 10 watt modulation transformer which should be adequate to modulate the transmitter. The modulator will most likely be a pair of 46's, driven by something like a 2A5. I am not sure as yet as to what to use as a driver transformer. I will need to study the books a bit before I decide on what to use. The microphone will be a candlestick carbon mic.
The transmitter deck is underway, with the oscillator stage nearly completed. A prototype oscillator using a #47 tube worked quite well. I am still undecided whether to use link coupling between the stages like Frank Jones did in his handbook or use capacitive coupling as are many ARRL designs. I'm leaning towards the link coupling scheme, as that way I can change the coupling to the 801 stage easily. The oscillator will use plug in coil forms and will oscillate on either 160, 80 or 40 meters. The 46 will operate as a straight thru (neutralised) amplifier, and (may) use it as a doubler for 20 meters.
The transmitter is still in its planning stages, and am still researching the circuit which suits me and the power supply requirements I have. The #47 seems pretty standard for a crystal oscillator so that's what I'm using.