You must have missed reading the description and seeing the HP8924C at the end of the video that is generating the BFO frequency. Also there’s the third winding on the coil form which is where the BFO is being injected.
The BFO signal is feed into the coil on the far left. The middle coil is connected to the antenna. The big coil all the way on the right is the tuning/tank coil connected to the variable condenser. The diode is tapped into the tank coil at 20 turns. The tuning condenser goes through the switch labeled "Band Shift" and the two position of that switch go to the taps at 60 and 80 turns. The tank coil has a total of 100 turns (the 100th turn tap isn't used). Flipping the switch on the right up (labeled 160m/broadcast) puts a small trimmer cap in series with the main tuning condenser to lower the capacitance and tune the 160m band.
@@k9yk Thanks. The design looks to be a good one. I just had a somewhat clever idea for a project I will never do. I presume you know what a "stolen power radio" is but I will explain for others who may read these comments. Basically you need two crystal radios and a strong station you don't want to listen to. You tune one crystal radio to the strong station and put a large capacitor on its output. The voltage from the capacitor can be used as the power supply to run an amplifier connected to the other crystal radio. This lets you get a louder signal from a weak station you do want to hear. Now for the project idea. I wonder if I could make a BFO that takes so little power that it could be run from stolen power.
Very nice looking xtal set. I like that the toggle switches weren't brought out to the front of the set like is usually done; rather they're installed into the circuit layout. Very cool!
nice test! just indicate distance from now on? I have read 15 miles also 24.1KM approximately. and a schematic (from your Crystal RX) would also have been nice, I think
Yes, you do need a BFO. See my other video "Crystal Radio 160m SSB Test". Right at the end you'll see I'm using an HP 8924c analyzer to generate the beat frequency. It is injected into the crystal radio tank circuit via the 10 turn coil on the left side of the coil form.
The "Band Shift" switch on the radio is just selecting different taps on the tank coil. I mainly use this with the AM broadcast band to shift the tuning of the variable capacitor toward the top end or bottom end of the broadcast band to make tuning stations at either end of the band a little easier.
I added a small trimmer capacitor in series with the main variable (tuning) capacitor. This does two things: 1) reduces the total capacitance and raises the frequency range of the tank circuit 2) reduces the range of the main tuning capacitor which is an advantage for the smaller 160m band.
There’s no ‘toggle’ to select upper or lower sideband. If you tune the BFO below the SSB signal, then you are receiving upper sideband. Tune the BFO above the SSB signal and you are receiving lower sideband.
I was watching the Ham radio concepts guy and seen your call in the comments section. I had to do a double take. It use to belong to a friend of mine Steve Carey. He is silent key now. We had too much fun on the radio. Sure miss having him around. Enjoy, glad to see his call again.73! de WD9ICU
Wow never seen the house without the runway! Had no idea these videos existed, thank you for posting. Crazy how far technology has advanced in a short time
