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THE AM BULLETIN BOARD => Technical Forum => Topic started by: KB1KFI on February 21, 2005, 09:27:29 PM



Title: Making good AM out of an Icom
Post by: KB1KFI on February 21, 2005, 09:27:29 PM
Hi, this is my first post...
A simple, yet complex, question...
Has anyone made any successfull mods to
the Icom 706mk11g in the audio/modulation
areas?  Is it possible in your opinion to
de-yellify this beast?

Regards,
Cliff
K1KFI


Title: Making good AM out of an Icom
Post by: Art on February 22, 2005, 08:37:39 AM
You can make the receiver better. . .  in fact quite nice. Do the 6Kc filter thing and use an external AF amplifier. The TX requires major dehnyellification. I don't think any one has done it yet. Pressed to perform I would locate the DBM and use an external AF chain and impedance matching/isolation to feed it. . . . this site might help you with the reference materials;

http://www.geocities.com/k3xf/ic706.html


Title: Making good AM out of an Icom
Post by: Art on February 22, 2005, 03:06:44 PM
I did some perusing of the schematic, board layout, and transmit theory for the IC-706mk2g. . .  the balanced modulator is on the bottom of the main board (IC1041). I would feed an external audio input (pin 1) at line level through a 10dB fixed attenuator (say 600 Ohms in and 600 out for the purposes of experimentation) and a nice fat cap (a 4.7uF tantalum might be a good choice). I would set R1042 for about 5W carrier and adjust your input AF drive for about 20W PEP.
I don't know anyone who has done this yet so you are on the bleeding edge and of course, the standard disclaimer applies . . .  you can really trash your radio if you are not familiar with small components and butcher the board. . .if you are not 100% sure you can handle it . . . don't

-ap
AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands