Actually, you have a 2-quadrant modulator/multiplier. The carrier swings both positive and negative (I and III quadrants) while the modulating signal (sine plus constant) is confined to the I quadrant.
Basically you can use the same circuit in the U.S. too. I mean you don't need modification. The reason of this is Japan has similar to your band plan (535k to 1605k with 9k spacing). My transmitter works at 1030kHz.
One question about the ferrite loop-stick antenna.
The specification is for 300uH. I found a 470uH with no tap. I found a second ferrite Loopstick antenna 680uh with tap at 470uh. How critical is the 300uH?
What adjustments do I need to make to use this?
Also can I use and external wire antenna? I note you have two phone jacks on the side, one for audio in. What is the second phono plug for? Thanks.
300uH is not so critical.Q of the resonator is critical thing. R107 (dumping resistor) in Figure 1 controls Q. And R107 also working for prevention self oscillation. If you have strange phenomenon, please adjust R107.
I think 680uH/470uH (tap) is not bad choice.
About an external antenna, remaining one jack is for external antenna. 3rd picture in the video, plunger is my favorite external antenna!
Actually, you have a 2-quadrant modulator/multiplier. The carrier swings both positive and negative (I and III quadrants) while the modulating signal (sine plus constant) is confined to the I quadrant.
MichaelJGrant 1 month ago
Hi,
At the modulator/multiplier (TR101 Emitter), the carrier doesn't have negative voltage.
Could you refer to Figure 3 or 4 in downloaded document (pdf) from my homepage?
Carrier swings 0V and positive voltage . Negative voltage (III quadrant region) generates with LC resonator.
So modulator works at 1-quadrant region.
From this, I call 1-quadrant modulator.
Thank you for the comment.
mkatsube 1 month ago
How DO you modify the circuit to play on USA.... MW band (BCB or broadcast band).
USA as you know is 530Khz to 1700Khz with 10Khz spacing..... Thank you.
gmcjetpilot 2 years ago
Hi,
Basically you can use the same circuit in the U.S. too. I mean you don't need modification. The reason of this is Japan has similar to your band plan (535k to 1605k with 9k spacing). My transmitter works at 1030kHz.
Thank you.
mkatsube 2 years ago
Comment removed
gmcjetpilot 2 years ago
One question about the ferrite loop-stick antenna.
The specification is for 300uH. I found a 470uH with no tap. I found a second ferrite Loopstick antenna 680uh with tap at 470uh. How critical is the 300uH?
What adjustments do I need to make to use this?
Also can I use and external wire antenna? I note you have two phone jacks on the side, one for audio in. What is the second phono plug for? Thanks.
gmcjetpilot 2 years ago
300uH is not so critical.Q of the resonator is critical thing. R107 (dumping resistor) in Figure 1 controls Q. And R107 also working for prevention self oscillation. If you have strange phenomenon, please adjust R107.
I think 680uH/470uH (tap) is not bad choice.
About an external antenna, remaining one jack is for external antenna. 3rd picture in the video, plunger is my favorite external antenna!
Thanks.
mkatsube 2 years ago