[TenTec] Orion 1 & 2 "Talk Power" problem

[Ron Castro]

I have had a couple of people contact me off-list a problem with the v. 2.x Orions regarding the ability to drive external amplifiers to normal average power levels in SSB.  I have referred to this as the "Talk Power" problem.  A few weeks ago, I looked at the SSB wave form under normal speech on a spectrum analyzer and found that very few voice peaks approached the output level reached when measuring CW output for the same power-level setting.  This appears to be a result of an extremely slow release time in the ALC circuit.  This may be great for preventing CW key-clicks, but looks like very low average power output in SSB.

I'm wondering if the ALC is controlled by the CPU or if this is a purely hardware-related function.  Looking at the schematic (A5 ALC.pdf in the O2 schematics), it looks to me like R9 and C5 set the timing, and if my math is right, that combination (470 k and 4.7 mf) should result in an 8.7 dB "release" over a period of 2.2 seconds.  If the control is actually digital or combined with a digital override, then the time constants can be completely different.  I sounds to me like very fast attack and very slow release.

Has anyone else noticed this problem and what thoughts do you have on it?  Also, does anyone know what parameter R-19 in the schematic adjusts?

      Ron N6IE
 www.N6IE.com
(Formerly N6AHA)