I have built the poppet top band am transmitter from the sprat cd. It is
transmitting the am carrier ok, but there is no modulation.
Can anyone suggest how I can test the microphone amplifier circuit.
73 David

David Roper wrote in message
...
I have built the poppet top band am transmitter from the sprat cd. It is
transmitting the am carrier ok, but there is no modulation.
Can anyone suggest how I can test the microphone amplifier circuit.
73 David


David,

I am going to build this tcvr soon too, please let me know how you get along
with this project.

73's Simon G7CPN.

David Roper wrote in message
...
I have built the poppet top band am transmitter from the sprat cd. It is
transmitting the am carrier ok, but there is no modulation.
Can anyone suggest how I can test the microphone amplifier circuit.
73 David


David,

I am going to build this tcvr soon too, please let me know how you get along
with this project.

73's Simon G7CPN.

Hi Simon
I have the tx section working great, a local station can hear my carrier
very strong, but the modulation is very distorted. I am using an electret
microphone, I may try a different mic. I will keep you posted if you send
your email. Please let me know if you encounter the same problems.
Hope to hear from you soon.
I would be very greatful if anyone has any ideas on how to test the mic amp
circuit.
David. 73
"SB" wrote in message
...

David Roper wrote in message
...
I have built the poppet top band am transmitter from the sprat cd. It is
transmitting the am carrier ok, but there is no modulation.
Can anyone suggest how I can test the microphone amplifier circuit.
73 David


David,

I am going to build this tcvr soon too, please let me know how you get
along
with this project.

73's Simon G7CPN.

Hi Simon
I have the tx section working great, a local station can hear my carrier
very strong, but the modulation is very distorted. I am using an electret
microphone, I may try a different mic. I will keep you posted if you send
your email. Please let me know if you encounter the same problems.
Hope to hear from you soon.
I would be very greatful if anyone has any ideas on how to test the mic amp
circuit.
David. 73
"SB" wrote in message
...

David Roper wrote in message
...
I have built the poppet top band am transmitter from the sprat cd. It is
transmitting the am carrier ok, but there is no modulation.
Can anyone suggest how I can test the microphone amplifier circuit.
73 David


David,

I am going to build this tcvr soon too, please let me know how you get
along
with this project.

73's Simon G7CPN.

David Roper wrote in message
...
Hi Simon
I have the tx section working great, a local station can hear my carrier
very strong, but the modulation is very distorted. I am using an electret
microphone, I may try a different mic. I will keep you posted if you send
your email. Please let me know if you encounter the same problems.
Hope to hear from you soon.
I would be very greatful if anyone has any ideas on how to test the mic
amp
circuit.
David. 73
David,

Glad to hear you have the RF section working well, as far as the modulator
goes I would treat it as a stand-alone mic amplifier circuit. I would
suggest you connect the output pin 5 of the LM386 to a speaker via a 220uF
electrolytic cap ( + towards the pin 5) and monitor the modulation quality
from the speaker.

73's Simon G7CPN.

David Roper wrote in message
...
Hi Simon
I have the tx section working great, a local station can hear my carrier
very strong, but the modulation is very distorted. I am using an electret
microphone, I may try a different mic. I will keep you posted if you send
your email. Please let me know if you encounter the same problems.
Hope to hear from you soon.
I would be very greatful if anyone has any ideas on how to test the mic
amp
circuit.
David. 73
David,

Glad to hear you have the RF section working well, as far as the modulator
goes I would treat it as a stand-alone mic amplifier circuit. I would
suggest you connect the output pin 5 of the LM386 to a speaker via a 220uF
electrolytic cap ( + towards the pin 5) and monitor the modulation quality
from the speaker.

73's Simon G7CPN.