[TenTec] Orion 1.373b5 Audio

[Merle Bone]

I have had my Orion for a little over two years and have always gotten, unsolicited, really good audio comments  I'm not an "audio aficionado" but I do use a W2IHY 8 band equalizer that I got for my Yaesu transceiver. I'm using the TenTec mike built by Heil. I have generally used some signal processing - a setting of 3 - for general communications. I have occasionally increased the SP to 4 or 5 for DX work - DX'ing is my favorite part of the hobby. 

Recently I had a friend, Tom, - who knows my voice well - run a hour of audio testing with me on 10 Meters. We first ran the audio with no speech processing and then ran it with various levels of processing. Tom has been a ham for almost 50 years and he has an outstanding ability to evaluate signals on the air. I ran the speech processing at 3 and he said very good. At 4 he said very good. At 5 he said really very good. At 6 he said great audio. With the speech processing at 7 he said you are filling the room with great audio. He called it "golden audio (He also listened carefully to check the bandwidth of the signal to see that it was really clean on 10 Meters)." At 8 he said its starting to sound a little harsh, but perfectly intelligible. 

The speech processing technique in V1.373b5 was described by Doug Smith as:

"It might seem funny but in a DSP transmitter, it is relatively easy to compute the transmitter's RF envelope before the modulation is even performed! That, in turn, makes it possible to preprocess the audio applied to the modulator to get exactly the same effect as that produced by an RF compressor. Post-modulation band-pass filtering maintains the desired occupied bandwidth. As the decay time of the compressor is decreased, an RF compressor approaches the behavior of an RF clipper, long known to be the most effective form of speech processing for SSB. In combination with the Orion's transmit equalizer, results are quite dramatic."

Tom agreed that the results were dramatic. 

I run a modest station because of antenna limitations (Force12 C3SS 7 feet above the peak of the second story roof). Recently I have been running the Speech Processing - V1.373b5 - at 7 for DX work. Tonight there was a pretty good pile-up on the Western Sahara S01R on 20 Meters. He came back to me after one call. Now I always "cringe" when people use that "one call" phrase -because "stuff happens", but I think it correctly characterizes what I have observed of the performance of the Orion with higher levels (7) of Speech Processing on SSB.  Doug Smith said "15 dB of R.F. compression can produce up to 6 dB of intelligibility improvement on the receiving end. This is equivalent to a quadrupling of output power!" I am certainly not an expert in this area but the performance of the Speech Processing in the Orion V1.373b5 is a great complement to the receiver.

You may want to run some tests of your own.
73,
Merle - W0EWM