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Title: BIFET Compressor Mic and IC-718 by WA7JHZ Post by: Steve - K4HX on October 30, 2018, 02:24:25 PM The attached JPG shows what I've been doing with my BIFET compressor mic and Icom IC-718. Followed by a decent linear amplifier, it is hard to tell the difference between it and a modified broadcast AM transmitter.
Title: Re: BIFET Compressor Mic and IC-718 by WA7JHZ Post by: Steve - K4HX on October 30, 2018, 02:26:18 PM The attached JPG shows a reversed order between the 4 kHz LPF and AGC/peak-limiter on my proposed compressor mic circuit. The complex phase shift of the LPF occurs before the AGC/peak-limiter, and its noise and distortion are low enough to allow this. Note that I've also added a positive modulation control circuit (U12).
Title: Re: BIFET Compressor Mic and IC-718 by WA7JHZ Post by: ab3al on October 30, 2018, 05:48:00 PM does this improve the audio bandwidth of the transmitter or just controll the agressive agc. looking at it from my phone cant see to well
Title: Re: BIFET Compressor Mic and IC-718 by WA7JHZ Post by: Steve - K4HX on October 31, 2018, 11:07:51 AM This circuit is to control modulation levels. There is a 4 kHz lowpass filter to limit higher frequencies. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
In general, the only way to improve the audio bandwidth of a transmitter is to modify the transmitter, not with external boxes. Yes, an equalizer can overcome some inadequacies but there are limits to this approach. |