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Wednesday, June 24, 2020

Orion AGC Settings by Len, WT9G

Hi all,

found it on QRZ.com > all rights reserved to Len, WT6G.

After playing with the Orion for over a year I've come up with a procedure that appears to really work for these settings and I thought I'd write it up.

First, one comment. The AGC Hang time is VERY useful for FAST AGC in CW mode. Dots are often short enough at high speed, but some operators shorten them intentionally. Frequently the signal length of a single dot is so short the AGC of any rig has trouble acting properly, which makes the signal harder to copy and leads to operator fatigue.

This is easily fixed using the AGC Hang time. I typically use a hang time of .12 seconds or less for about 22 wpm, but if you are slower you can increase this a bit. I've played with settings as high as .25 seconds for novice speeds, and find values of .04 and .08 more useful for high speed CW during contests.

This setting means that once the agc level is determined by a signal, the dsp will hold that level for the indicated amount of time. It helps to visualize this in terms of the frequency that the signal is "evaluated". For example, if the Hold Time is set for .250 Seconds, the AGC will be evaluated 4 times per second, or once every 250 milliseconds. This is ok for very slow CW. Faster speeds should use faster sampling or shorter Hold Times. The Orion offers holdtimes of .04 .08 and .12 seconds, which are very useful for fast CW. Try adjusting this while listening to CW on your favorite band with the Fast AGC set and you will really see what a great feature Hold Time can be!

To set the SQUELCH control use the following procedure:

1. Preamp OFF, RF Gain 100, no antenna connected, AGC slow Set the bandwidth for the mode you normally use with slow AGC ie SSB, 2.8 KHz

2. Select the Main RX then got to Menus, RX and select Main RX Sql.

3. The default is -127 dBm. Decrease this until the audio is squelched. Be sure to find the exact point where it squelches. On my Orion this happens at -110 dBm.

4. Now select the slow Threshold for Main AGC and increase the number slowly from the default .37 uV until the radio unsquelches (ie The audio comes back. On my Orion this happens at .59 uV.

At this point, your DSP has some reasonable levels for Squelch, and AGC threshold. The audio should never be muted by the squelch and the AGC action will begin at a realistic level for your radio.

You may notice, if you don't set these values as I've described, that the RF gain control will unsquelch the radio as you decrease it if you have the squelch set.

To demonstrate this, leave the sensitivity set at .37, squelch the audio, and then return to normal operation and decrease the RF Gain below 100. My audio pops back on! Once you follow the procedures outlined above, this little anomaly will go away, and you will note what appears to be a smoother operating AGC. I didn't write the code, and it's not Open Source so I'll have to admit some lack of knowledge on the exact effect this has on the radios firmware, but it seems to improve performance.

Repeat the procedure for "med", "fast" and "prog" at the bandwidths you typically use for each of these. I set up "slow" and "med" at 2.8 KHz. "fast" and "prog" are set up at 250 Hz. "fast" and "prog" work nicely at 500 Hz when set for 250 Hz.

AFTER the AGC is set up, you can adjust the Hang Time for the AGC speeds you normally use in CW. On my orion I set this to .12 for "fast" and .08 for "prog". I also set the decay slope at 200 dB/s for "prog", 5 dB/s for "slow", 40 dB/s for "med", and 80 dB/s for "fast".

In CW, I usually use "fast" and then switch to "prog" for really fast QSO's. I use "slow" and "med" for SSB with no hang time.

NOTE: If you set your bandwidth too narrow, (ie 100 Hz) you may have
trouble making these adjustments. I recommend 250 Hz minimum because at 100 Hz it's sometimes hard to hear enough noise without a signal to tell if the RX is squelched or not. Of course this note applies to CW ops. You can get really confused if your filters are not centered.

Accordingly, you should have the additional roofing filters properly  centered before you make the AGC adustments. This is simple to do. I accomplish it as follows:

a. Select a bandwidth using the BW control equal to the filter you are aligning. For example, 500 Hz or 250 Hz. Tune in a cw signal and in the Filtr menu vary the Center Frequency Adjustment.

b. As you move it around you should see your S meter change. note the points on the ends where the signal goes away (a weak signal will drop completely out) This will give you two numbers. For my 500 Hz filter, I noticed the signal edges appeared at -200 and +550. (this depends on signal strength).
The difference between these points is 750. Divide this by 2 to get the center of the passband, and then add this to the lowest number to get the absolute setting. 750/2 = 375 -200 + 375 = 175 ... I set the control to 170 since values of 10 are the only resolution available. Obviously you can do this quite accurately with a voltmeter on your audio and a constant CW tone signal source, but you get "close enough" by ear for all practical purposes.

I find a strong CW signal and the S Meter is pretty accurate to find the edges.

Don't be surprised if you start to hear some incredible stuff while ou're adjusting these settings. I was on 40 meters adjusting my 250 Hz filter after the last software upgrade and copied some JA's in QSO.

There is nothing like a 250 Hz roofing filter followed by a 100 Hz  DSP filter that does not ring! With the settings made as described above you can actually tune accross the band at 100 Hz bandwidth in 10 Hz or less step width and hear and work stations!

I have all of the roofing filters in place from 250 Hz up, and I love the performance of the Orion. There's nothing like it at any price.

/Len WT6G

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