[AMRadio] Apache Audio Mods

[JAMES HANLON]

Electric Radio Magazine published two articles on audio mods for the Apache.

In issue # 20, December 1990, Ken Morgan KC5DW reported that the audio bandpass of his stock Apache began to roll off at 1600 Hz and was down by 6 dB at 600 Hz.  On the high frequency end it was down by 3 dB at 3600 Hz.  Ken changed C61 and C64, both 510 pf audio coupling capacitors between the first and second and second and third audio stages to 0.0047 mfd units.  He then measured the lower frequency 3 dB point to be about 2000 Hz.

In issue # 150, November 2001, Glen Zook K9STH did a similar job.  He replaced C61 and C64 with 0.01 mfd, 400 volt Orange Drop caps and also replaced C60, another audio coupling capacitor between the third audio stage and the clipper, with a 0.01 mfd, 400 volt Orange Drop.  C60 was originally a ceramic capacitor, and Glen preferred to use an Orange Drop.  He did not measure the bandpass, but he reported that his modified audio was much more "natural sounding."

I can scan copies of the two articles for anyone who is interested.

Jim, W8KGI