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Tuesday, August 13, 2019

TT Orion 565 on 160m & optimal setting - part V. by YT1NT (AGC threshold comments)

As I promised last time there I am posting the compilation of the comments by Sinisa regarding the AGC threshold and principles uses on the Orion 565 receiver.

I hope it will help to Orion's owners to understand all of the neccesary details to be able to effectively use AGC setting on their Orions.

see text as follows:


Richard Detweiler wrote:
> When the noise drops down as the agc threshold is increased,
> what is happening, is the noise is dropping below the point
> at which the AGC will try to amplify.


When AGC Threshold is increased, gain is
immediately reduced in the same proportion.
No automatic action here, and AGC never "tries"
to do anything else apart from maintaining
constant volume.

There is only one AGC Threshold,
and, for any given threshold value,
signals above it are attenuated
to maintain constant volume.

No attempt is made to amplify signals
below the threshold, an no attempt is made
to improve S/N ratio or anything else,
apart from maintaining constant volume.

> This is a Good thing, because hopefully the weak signal
> just above the noise is not below that point and it will then
> amplify only the signal of interst,


This reminds me of a myth about Orion's AGC
being fundamentally different from usual
implementations, i.e. being able to reduce
noise and amplify desired signals.

Unfortunately, there is no such a miracle.

At instants when both signal and noise are present,
signal to noise ratio does NOT depend at all on AGC
Threshold setting. And AGC action tends to reduce,
NOT increase the apparent signal to noise ratio,
as perceived with intermittent signal.

Orion's AGC action does not bring anything fundamentally new,
although the level of user control is greater than usual.
The user may or may not achive optimum settings,
depending on skill and willingness to play with controls.

By setting the AGC Threshold just above the
signal + noise level, AGC is essentially
turned off, with two benefits:

a) intermodulation between the signal and the noise
through AGC action (acting as undesired amplitude modulation)
is avoided;


b) our aural system doesn't get confused by fast and
frequent changes of gain.


The sole remaining AGC function is that of
protecting our ears from unexpected
strong signals. Not a miracle, but useful.

73,
Sinisa YT1NT, VE3EA

That's all regarding the Orion 565 receiver setting at this moment. When I will have some another information then I will post them. Do not hesitate to email me if You will have another usefull informations or experiences with that tcvr on Topband.



73, Petr OK1RP  
...-.-  

TT Orion 565 on 160m & optimal setting - part IV. by YT1NT

USING TT ORION's 565 RECEIVER
by Sinisa Hristov YT1NT, VA3TTN shristov@ptt.yu
 
Version 0, Feb 28, 2004
 
Overview
Perform the steps in this order:
* initial adjustments,
* start an audio analysis program (optional but very useful),
* set the optimum RX sensitivity for the given environment,
* set AGC to avoid it causing distortion to weak signals,
* adjust filters according to band conditions.
 
Initial Adjustments
1. Connect and select the desired antenna.
2. Use studio quality stereo headphones (my choice: Beyerdynamic DT-770 Pro or DT-109 headset). Good isolation from room noise is essential.
3. AUDIO menu:
* set LEFT, RIGHT and SPEAKER to MAIN or BOTH;
* turn off BinRX;
* set both RX EQ values to 0 dB.
4. RX menu:
* main AGC hang = 0.30 s (for fast contest operation decrease it later to 0.00 s)
* main AGC decay = 5 dB/s (for fast contest operation increase it later to 10-15 dB/s)
* PBT/BW STEP = 10 Hz.
5. OTHER menu:
* all five rates to FAST.
6. FILTR menu:
* XTAL FILTER = AUTO (for CW operation 1 kHz filter provides best dynamic range)
* enable optional filters that are present
* DSP FILTER LENGTH = 199 taps.
7. Set controls:
* MAIN RX = ON
* LCK = OFF
* select desired frequency
* ATTN = OFF
* AGC = PROG
* SWEEP = OFF
* STEP = 10
* SPOT = desired value (my choice is 600 - 700 Hz; with wide CW filters use 800-1000 Hz)
* RF GAIN = 100
* PREAMP = ON
* MODE = desired mode
* NB = OFF
* NR = OFF
* NOTCH = OFF
* AN = OFF
* RIT and XIT = OFF
* MAIN AF GAIN to a comfortable listening level (disable sub RX AF GAIN)
* select CUT L, rotate the knob to set PBT = 0 Hz for CW and PBT = 150 Hz for SSB;
later in operation: use the knob to cut low-pitched interference on SSB;
* select BW, rotate the knob to set BW = 500 Hz for CW and 2100 Hz for SSB
later in operation: use the knob to adjust CW filter bandwidth or to cut high-pitched interference on SSB.
 
Sensitivity
 
Theory
The ultimate limiting factor in receiving weak signals is noise, and not receiver's "gain".
The total noise power audible from headphones is a sum of:
* internal receiver's noise, and
* external noise coming from the antenna and being received just like any other signal.
Receiver's noise must be weaker than external noise if the receiver is not to degrade reception. It is recommended the internal noise level to be 10-12 dB below the external noise level. This way the internal noise will cause negligible increase in the total noise power. The audible signal-to-noise ratio will be determined solely by external noise. However, there is no point in making receiver's noise weaker than external noise by more than 10-12 dB. Signal-to-noise ratio cannot be improved that way, and the receiver would become more susceptible to overload. The optimum sensitivity level clearly depends on the environment - location, frequency, antenna and propagation. Therefore, a new adjustment is needed whenever the environment is changed. A common mistake is to use the as much gain as available, regardless of actual conditions. This is wrong - too much gain seriously impairs receiver's ability to receive weak signals in the presence of interfering strong signals, thus degrading the effective sensitivity.
 
Adjustment
The following procedure is specifically tailored to Orion's controls, but the method is the same with any receiver.
Connecting and disconnecting the antenna should result in noise level difference of 10-12 dB (~2 S units).
If RX AUX connector is not used, one can simply press MAIN RX/TX RX ANT key.
Strictly speaking, the antenna shall be replaced by a 50 Ohm termination (on RX AUX connector).
Anything more than 10-12 dB overloads the receiver unnecessarily.
Anything less than 10-12 dB reduces the signal to noise ratio.
Start with full sensitivity and reduce it until the above condition is satisfied.
Orion has 3 sensitivity controls which should be reduced in the following order:
* PREAMP turned off;
* ATTN increased to 6, 12 or 18 dB;
* RF GAIN reduced.
If the external noise moves the S meter sufficiently, one can use its indication which is reasonably accurate and does not depend on AGC THRESHOLD setting.
If the test is done by external instrumentation or by ear, AGC THRESHOLD must be increased slightly above the point where the external noise volume starts to decrease. This ensures that AGC will stay inactive, and what is heard (and measured) will reflects actual power ratios. The exact point is not critical and may be much higher than the minimum one. Of course, the selected setting must not be changed during the test.
 
AGC
 
The Purpose
The purpose of AGC [Automatic Gain Control] is to avoid overload of ears by reducing the gain for strong signals. Unfortunately, as implemented in Orion and most other receivers, AGC can degrade weak signal reception. AGC essentially divides the signal by a rectified and filtered version of it, creating intermodulation which is particularly bad with a weak signal near the noise level. The signal and the noise get intermodulated, significantly reducing readability. Therefore, the AGC action is undesirable with weak signals. However, AGC must stay on in order to protect ears from unexpected strong signals. The purpose of AGC adjustment is to provide the optimum tradeoff between readability and protection.
 
Orion's AGC Controls
Orion has four sets of AGC settings: SLOW, MED, FAST and PROG. Each set is independently adjustable with PROG providing the widest range of adjustment.
Within RX menu there are three AGC settings (with separate values for each of the sets):
* AGC HANG time,
* AGC DECAY rate,
* AGC THRESHOLD level.
AGC is inactive for a HANG time long period after a signal peak that determined the latest gain reduction. During that period the gain is held at a fixed level, resulting in two benefits (until the "hang" period ends):
* the job of our aural system is made easier, in part by not raising noise level between characters/words;
* the usual AGC-induced intermodulation is avoided.
When the "hang" period expires, AGC starts increasing the gain at AGC DECAY rate. Faster rate enables the receiver to recover gain in shorter time, but too fast a rate will reduce readability due to disproportionate increase of noise and interference volume.
 
AGC THRESHOLD
AGC THRESHOLD determines the signal level above which the AGC starts to reduce the gain.
On "typical" receivers, RF GAIN control can be used to superimpose DC control voltage (and move S meter) making AGC loop inoperative for signals that do not move S meter anymore. This is a very effective weak signal technique. There is an Inrad flyer recommending its use on FT1000MP. One simply turns RF GAIN counter-clockwise until the S meter stops responding to noise peaks.
Contrary to popular belief, no sensitivity is lost by reducing RF GAIN control in this way, because the actual gain would have been reduced by AGC anyway.
Orion's RF GAIN does not control the AGC threshold directly. Orion users have to activate menus and then select and change the clumsy AGC THRESHOLD setting (which does not move the S meter), instead of simply turning a knob counter-clockwise as on "less modern" receivers. Therefore, speaking ergonomically, Orion's AGC THRESHOLD control is less adequate for the purpose due to:
* lack of correlation between AGC THRESHOLD values and S meter noise readings;
* lack of dedicated knob.
Both disadvantages can be overcome, but the price in time and effort may simply be too high in contests.
Particularly cumbersome is to know "how much of it" to apply, compared to RF GAIN method where one simply looks for a non-moving S meter.
Menu readings are given in microvolts. The manual is not explicit where are these microvolts measured.
One is tempted to assume that they are measured at the antenna connector and can therefore be correlated with S meter indication on the basis of S9 = 50 uV and +1 S unit = doubling the voltage. However, such an assumption is wrong. Despite 0.01 uV resolution, indicated AGC THRESHOLD levels are grossly inaccurate. On my Orion measured AGC threshold levels are ~21 dB below set values with preamp on, and ~9 dB below set values with preamp off.
 
Adjustments
Sensitivity adjustment must be performed first, as described above.
If the external noise is kept at the same level on various bands (S 3 level is recommended), then AGC settings may also stay the same.
Adjusting AGC THRESHOLD by instrumentation or by ear:
* ensure that sensitivity is correctly adjusted, avoiding noise readings above S 8;
* starting with a low value, increase AGC THRESHOLD until the external noise volume is reduced by ~15 dB (~2.5 S units); external noise will remain comfortably audible, but not as strong as usable signals;
* adjust AF GAIN for comfortable volume.
Adjusting AGC THRESHOLD by S meter:
* ensure that sensitivity is correctly adjusted, avoiding noise readings above S 8;
* adjust AGC THRESHOLD ~2 S units above the S meter noise readings, according to the table above; external noise will remain comfortably audible, but not as strong as usable signals;
* adjust AF GAIN for comfortable volume.
AGC DECAY can be kept at 5 dB/s (slightly faster in contests), with AGC HANG time at 0.30 - 1.00 seconds.
 
FILTERS
 
Roofing Filters
The purpose of roofing filters is to protect stages after the first mixer from strong adjacent signals.
Orion repeats the mistake of earlier receivers by overloading the weak stages after the first mixer and then attempting to escape from IM problems by putting in narrow roofing filters, which works down to 1 kHz, but then breaks up after amplification is added with 500 Hz and 250 Hz filters.
The filters work very well, in spite of not being shielded.
Both 500 Hz and 250 Hz filters should be centered. The procedure given in the manual suggests positioning the peak gain point on the spot frequency. This will not work with slightly asymmetric pass bands. It is better to use an audio analysis program and position -3 dB or -6 dB points symmetrically around spot frequency.
 
Measured Roofing Filter Performance using 200 Ohm termination
 
nominal
bandwidth
standard
order
insertion loss
bandwidth
-3 dB -60 dB
group
delay
[Hz]
option
[xtals]
[dB]
[Hz]
[Hz]
[ms]
6000
standard
4
1.02
5521
24570
0.18 - 0.34
2400
standard
4
0.96
2174
10250
0.43 - 0.75
1800
option
8
2.85
1768
3171
1.10 - 3.15
1000
standard
4
2.12
920
4672
0.98 - 1.68
500
option
8
6.86
454
1178
3.30 - 5.50
250
option
6
10.09
225
796
4.90 - 7.00
 
Interested parties should email me for bandwidth and group delay sweeps in JPG format.
 
DSP Filters
DSP filters provide Orion's ultimate selectivity. Recommended use of filters knobs is described at the end of "Initial Adjustments" section. Particularly valuable is the ability to change filter bandwidth and to shift the pass band without causing any disturbance to received audio, unlike so many other receivers. It is a widespread myth that a narrow CW filter enables the operator to hear weak signals buried in white noise and not audible with wider filters. This simply doesn't happen, at least not before the bandwidth is reduced very much below ~50 Hz (with slow telegraphy). This comes from the fact that our aural system performs a very good signal processing, effectively narrowing the bandwidth around a CW signal to about 50 Hz. But when the reception is limited by adjacent transmissions (not by white noise), a narrow CW filter can help a lot.
When using a narrow CW filter, it is most important to center the signal inside the filter pass band. Simply switching to a narrow filter may not help, and the desired signal may actually disappear if it is not centered. The centering is usually done using a VFO knob or RIT, aiming for the signal tone equal to the keying side tone. The SPOT key may be pressed to produce a beat note, but that will disturb the reception. A much better method is to use an audio analysis program and center the signal visually using the audio spectrum display. The spectrum display is also very useful for selecting an optimum filter bandwidth according to current conditions, and for adjusting low and high cutoff frequencies during SSB operation in order to optimally separate the signal from interference. It is also useful with the manual notch filter.
Well, it is the recommendation in an excellent article by Sinisa, YT1NT. In the next article I will post also some comments made by Sinisa regarding the AGC threshold values...
As I tested it on the Orion 565 the AGC is quite sensitive on Topband and in my case I had to use threshold values around 63 uV and even sometimes more than 90 uV.


73, Petr OK1RP
...-.-

Monday, August 12, 2019

TT Orion 565 on 160m & optimal setting - part III. by OK1RR

Preferred Orion 565 settings by OK1RR
 
Another thing which dictate my settings is headphones I'm using - KOSS SB-40 (affordably priced, comfortably to wear, excellent frequency response and sensitivity, dynamic boom mic, good separation from external noises and rugged construction).
 
I don't have the 302 Series Remote Encoder/Keypad and any of T-T Microphones. My radio is equipped with all T-T filters (250 Hz, 500 Hz and 1.8 kHz). I prefer the internal keyer which seems to have better QSK than my trusty Logikey MK III (oh, of course, QSK is very important to me). I have also the T-T 963 Switching Power Supply. The power cable is on both ends wound on small ferrite toroids (I used 5 turns on 1" dia yellow/white toroids, probably from a computer power supply, it seems like 26 stuff). This choking is a must unless you want RF in your power cable, which in my radio destroyed a capacitor in the antenna tuner).
 
So, after more than a year of intensive trials and manual reading I set my radio as follows:
 
MENUS
 
Menu item: TX
Internal tuner
disabled
Transmitter
on
Keying Loop 1
off
Keying Loop 2
off
EXT T/R Delay 1
0 %
EXT T/R Delay 2
0 %
Transverter
off
160M Antenna
---
80M Antenna
---
60M Antenna
---
160M Antenna
---
40M Antenna
---
30M Antenna
---
20M Antenna
---
17M Antenna
---
15M Antenna
---
12M Antenna
---
10M Antenna
---
Amp Key Tracks
Key Line
Notes: The Internal tuner is quite good in its matching capabilities but I dislike it - it is loud, slow and there are no memories, so any band change needs a new tuning procedure. I want to ask T-T engineers why they didn't include the memories - is it too expensive? Unfortunately LDG stopped their production of OT-11P which is fully integrated with the Orion and has all the bells and whistles you can expect in so advanced radio like Orion.
 
Menu item: CW
CW QSK Delay
0 %
Internal Keyer
on
CW Weighting
83 %
Sidetone Pitch
390 Hz
CW Rise/Fall
3 ms
SSB: CW Jack PTT
off
PTT in CW as
Key
Keyer Mode
B
Notes: The CW Rise/Fall of 3 ms is not optimal but at 6 ms the radio warns Max. 40 WPM External keying. I hardly run under 20 WPM but quite frequently over 40 WPM, sometimes also with external keyer (Logikey MK III). My tests shows that 50 WPM with Rise/Fall above 4 ms starts to sound choppy also with internal keyer. So, my 3 ms seems rather aggressive but nobody complained about my clicks.
 
Menu item: VOX
VOX Trip Level
10 %
Anti-Vox Level
20 %
VOX Hang
0.04 sec
Notes: Honestly said, I never used VOX. I'm hardly on SSB and if trying this less-preferred mode, I'm using foot switch.
 
Menu item: RX
Sweep Range
72 kHz
Main AGC:
Hang
00.00 s
[prog]
Decay
91 dB/s
Threshold
8.93 uV
Sub AGC:
Hang
00.00 s
[prog]
Decay
91 dB/s
Threshold
8.93 uV
PBT Track
on
BW Track
on
Hardware NB
off
Main RX Sql
-127 dBm
Sub RX Sql
-127 dBm
PBT/BW Step
10 Hz
AGC Slope
2:10 dB
Notes: other AGC settings (slow/med/fast) are defaults. I assume that [prog] settings are my individual and other are factory defaults. I use mostly my [prog] settings which are good for low band DXing. Don't switch Hardware NB on in the menu! Your receiver might seem very poor in spite of intermodulation parameters! Sweep range is rather individual, I dont't like the sweep option very much. The Sql settings are minimal.
 
Menu item: Filtr
Xtal Filter
Auto
Enable 1.8 kHz
Yes
Enable 500 Hz
Yes
500 Hz C. F. Adj
-20 Hz
Enable 250 Hz
Yes
250 Hz C. F. Adj
-20 Hz
DSP Filter Length
199 Taps
Notes: The Xtal Filter AUTO option is a bit risky under harsh contest environment. Both 500 and 250 Hz slots have an additional amplifier equalizing the filter insertion loss which causes worse IP of about 6 dB. In a contest, it is worth to change this option to 1 kHz. On low bands, sometimes a DSP Filter Length reduction to 124 or 104 Taps might result in a better S/N ratio and improved readability.
 
AUDIO
Left:
Both->
Right:
Main->
Spkr:
Both->
BinRX:
off->
TX EQ:
-15 dB
RX EQ:
0 dB
SUBEQ:
0 dB
 
This settings allows to monitor my transmitting frequency in the left ear. I find it very comfortable because it is similar to my SO2R contest setup if using it. I recommend to experiment a bit here. Sometimes I'm using also the Binaural RX which make wonders in very noisy environment with lowered taps of DSP Filter.
 
 
73, Petr OK1RP
...-.-

TT Orion 565 on 160m & optimal setting - part II. by W4PA / KF6DX

Setting up the Orion for weak signal low band DXing
("single signal DXing")
 
With recent transceivers, a operator typically would set CW for a low or comfortable offset, select a narrow bandwidth filter (like 250 Hz), turn AGC to either "fast" or "off", use some setting for DSP noise reduction and start listening for weak signals. Which is fine - except that 'typical' settings like this used for other radiossimply won't use Orion to its maximum capabilities.
 
You can skip the entire document if you're merely looking for optimum initial settings for maximizing receiver performance. If you'd like a more detailed explanation of how these all work and interact, read on.
 
Set AGC to programmable and use these settings for prog AGC, NR, and Xtal Filter:
 
Threshold : 0.5 uV
Hang : 0.00
Decay : 40 - 60 dB/S
NR : 3 or OFF
Roofing XTAL : 1 kHz
 
An important point to ponder: There is no one setting for RX combination (defined as roofing filter, DSP bandwidth filter, DSP NR, and AGC together) that is the correct one for Orion. There are good places to start - and by understanding how the operation of the high dynamic range receiver in Orion is different from other transceivers will set you on the correct path toward optimum use.
 
Let's think this through logically. Band conditions always vary, noise always varies, signals always vary. If you set a transceiver for one optimal setting to use it for variable conditions, would it seem logical that the operator would be using the transceiver to its optimum capability each and every time? No.
 
Refer back to the above definition of the use of a crystal roofing filter. The roofing filter is used for keeping strong closeby signals from compromising receiver performance. Listening to a weak signal on a quiet band does not meet the definition of need for a tight roofing filter. On a band where few signals are present other than a desired target weak signal, only a wide roofing filter would be necessary. Putting in the 250 Hz roofing filter when listening to a single weak signal on the low bands gains nothing additional. In fact, it could hurt your ability to hear a noise floor level weak signal. Why? Among other reasons, all narrow bandwidth filters suffer from insertion loss - and in the Orion, like other transceivers have for many years, we use an amplifier to compensate for crystal filter loss. A 250-Hz filter is going to have slightly more loss than a 500-Hz filter. Both of these narrow filters have more loss than the 1 kHz roofing filter. The loss, after preamp compensation, is about 2 dB. No loud signals nearby = no need for a tight roofing filter. Regardless of DSP bandpass filter setting, we'd recommend using a wider roofing filter as acceptable for weak signal DXing. The DSP bandpass filtering does not vary in gain down to the minimum setting of 100 Hz. Therefore, if there is no offending signal within 1 kHz, setting the roofing filter at 1 kHz and narrowing the DSP bandwidth to any desired value is by far the best setup for Orion for single signal DXing.
 
 
Of course, if you have a pileup 1 kHz away, perhaps a tighter roofing filter is warranted to keep those loud callers from compromising close-in performance. That's fine - but make sure that the crystal roofing filters are centered (see bottom of page).
 
DSP noise reduction in the Orion interacts somewhat with the digital AGC system. Here is why: when turning on the noise reduction, without changing digital AGC, the receiver will get very quiet, very quickly. This is not the desired effect of noise reduction! The desired effect is to identify what is signal and what is noise and improve the ratio between the two, rather than making the whole receiver quieter, signals and noise. When DSP NR is selected, digital AGC artificially reduces the threshold setting of the digital AGC - and you will notice that the overall noise level can increase - but signal-to-noise ratio improves and that is the ultimate goal of the NR system.
 
In practical terms, how does it work? There are 9 different settings, and each of the 9 are used to determine only how aggressively (quickly) the NR adapts and identifies what is signal and what is noise. Here is the rub (and it's logical): with weak signals, it is harder for the DSP NR to determine what is noise and what is signal. When turning DSP NR on with a setting of "1" with a signal that is very weak, it's going to take a very long time for the algorithm to figure out what is signal and what is noise. For a somewhat louder signal (20 dB or more above the ambient noise level, still fairly weak) - a setting of "1" will adapt very fast! What is needed for weak signals is more aggression. By starting the NR at "3" or "4", the NR will more quickly adapt to what is signal and what is noise for a weak signal. Once the NR has adapted, for the same signal, no change in NR will be made when adjusting the value! If you turn the DSP NR on, and just cycle through the values looking for 'best' - nothing will happen. Because the DSP NR builds a bandpass filter to automatically reduce noise, it produces the same effect as manually selecting a very narrow DSP passband filter.
 
Perhaps nothing is more important than AGC setting, and for single signal weak signal DXing purposes the programmable AGC value is probably the only setting that the operator should consider using. Put the AGC hang at 0.00 - turn it off. Why? Because with AGC hang, the AGC will grab onto the most recent noise peak and will adjust gain to it for the hang period, then decay will begin - this is not good if you're trying to listen to a signal at the noise floor and band noise is varying on top of the signal! The threshold value in the AGC system acts like an IF gain control for the receiver chain - turn the value low (like to .37 uV) and the receiver gain comes up, as do the signal levels. The crucial part is adjusting decay and threshold. Decay is used to determine how fast the IF gain increases in the absence of a signal above the threshold value. For a conventional setting like 'fast' or 'off', either on Orion or any other transceiver, the AGC can actually clip both a weak signal and the noise! Want an example? Tune to a point on the band where there is no signal, only band noise. Set AGC hang at 0.00, threshold at .37 uV, and then start decay rate at 5 dB/s. Turn it up to 1000 dB/s (fastest setting). Hear the background noise change? That's AGC clipping the noise at the fast decay setting.
 
If there's a weak signal in there at that level - you guessed it, the signal gets clipped too.
How to use the programmable AGC for optimum performance for weak signal DXing: There are two possibilities. For each, set hang value at 0.00. The first example we'll call "quick decay, variable gain" Set the decay to 60 dB/s (which is still fairly fast) and the threshold at .37 uV while listening to a weak signal. As you increase the threshold to higher values, it is possible that the weak signal will come out of the noise as the system gain decreases and the AGC no longer clips the weak signal and the noise! The other method is "low threshold, varied decay" to set threshold at a low or the lowest value for maximum IF gain, and then use the decay control to adjust, starting from the slowest setting of 5 dB/s and working upward. As decay goes faster, it introduces clipping. When listening to a weak signal with threshold low, advance the decay until the point clipping starts (audible change in the noise component and/or loss of copy of chopping of the weak signal) - ideally, you want to adjust this to just before the clipping point for maximum copy of the weak signal.
 
So, all that being said, how about a "set-it-once-and-leave-it" value for programmable AGC for weak signal DXing?
 
As noted in the graph at the top, set AGC hang at 0.00, decay at 40-60 dB/s, and the threshold at .5 uV. This ought to provide a good enough combination of settings to allow just about anything that can be audible to be detected by the radio (and likely copied as well) and allow for plenty of gain. If you need 'just a little more', you can go in and change the AGC parameters for a given situation as described above.
 
While you can have an optimal starting point for programmable AGC - every signal and every noise situation is unique! This is precisely what makes this system so advantageous over traditional settings of 'fast' and 'off'.
 
Consider the settings we have suggested for single signal DXing: wider roofing filter, NR (if desired) at a start value of "3" or higher, use of programmable AGC, DSP bandpass filter set at any value desired. Now consider what we started with above: conventional settings on a past transceiver of 250 Hz crystal filter, AGC fast or off, DSP NR on. Let's say on Orion, you've put in the 250 Hz roofing filter, put the DSP BW at 100 Hz, turned the AGC to fast or off, put the DSP NR on "1", and then went to copy a single weak CW signal on the low bands. Knowing what you now know, what is the likely result? No chance that desired signal is going to be as copyable (or copyable at all!) as it would be with setting the transceiver to take it to its full capabilities.
 
To summarize for weak signal, single-signal DXing: Use the programmable AGC settings in the table above, adjusting if needed for each situation to enhance weak signal copy. Use the narrow roofing filters only if a loud signal is close enough to warrant it. Gain does not vary for DSP bandpass filters - use any value down to 100 Hz you feel comfortable with. For weak CW signals, either leave NR off or start NR at a setting of "3" or "4" for quicker adaptation. Make sure the narrow roofing filters, if you choose to use them, are centered using the C.F. controls in the menu.
 
Make sure the signal you are listening to is zero beat at the CW offset you have selected.
 
For more information please visit http://images.tentec.com/radio/pdf/565optimize.htm
 
 
73, Petr OK1RP
...-.-

TT Orion 565(566) on 160m & optimal setting - part I. by W4ZV

Hi all,
 
some TT Orion 565 newbies (566 also) have troubles to set up their new toy correctly (yes, these famous rigs are still in ham shacks of many operators mainly because of their excellent receiver, ergonomy and features). However, any setting is a very subjective matter I will try to gather as many informations and settings as possible from most experienced DX performers and low band DX-ers to be able to get an idea how it works and how to make own setting.
 
Orion's AGC Controls
 
Orion has four sets of AGC settings: SLOW, MED, FAST and PROG. Each set is independently adjustable with PROG providing the widest range of adjustment.

Within RX menu there are three AGC settings (with separate values for each of the sets):
* AGC HANG time,
* AGC DECAY rate,
* AGC THRESHOLD level.
 
 
Here are the AGC settings found worked best for Bill, W4ZV:
 
(Originally published on Topband mailing list)
 
At night I was listening to YI9ZF on 80 while waiting for him to move to 160.
He was right at my noise floor and was QRV for quite awhile before 0200.
It was an excellent chance to play with Orion's AGC settings, and also to experiment with K6STI's DSP Blaster on Orion's audio output.

         
Threshold : 95 uV       
Hang : 0.63       
Decay : 20 dB/S 
    
Using these, I could take Kas from about 339 to 449, and I seemed to be hearing better than most. At times he dropped below my noise floor to the point that I thought he had gone QRT. Then he would again rise above the noise and be OK copy.

I was frankly astounded at what DSP Blaster would do! It was not only helpful for finding Kas' signal using the waterfall display, but made Q4 copy into solid Q5 copy. The Coherent CW feature splits the signal into in-phase and out-of-phase components, and when you listen to this with stereo headphones, it almost makes the signal sound like it "jumps" out of the noise, even though it is only a theoretical and measured 3 dB difference. I saved both my settings for Orion and DSP Blaster so I can experiment more with this in the future.

I got everything set up on 160 after Kas QRT on 80, but he did not show up on 160 immediately. Both RA6AX and A45XR had decent signals and A45XR was peaking 569 at 0229 near his sunrise. He runs a kW to a vertical but with just a few radials, so I expected Kas' 100 watts to a 20m high inverted-vee would be much weaker. I was amazed to hear Kas on 1837 at 0230 CQ-ing with a 569 signal!


No DSP or fiddling to copy him 100%, although I had left Orion's settings as noted above. I worked him for #311 on Topband and listened to him for the next 1.5 hours until he QRT at his sunrise just before 0400. Kas peaked 579 so he was even stronger than A45XR was at his sunrise! The AGC settings were quite comfortable to use and I could copy most of the EU and Russian stations Kas was working (UN7AM was 579!), and even many that he could not copy...I felt like I was VE1ZZ! The only major problem was when some strong NA stations would call zero-beat and of course that took the AGC awhile to settle down afterwards. I believe it would be possible to use similar AGC settings in a contest especially if you didn't have extremely strong stations inside Orion's passband. I may give this a try if I decide to do ARRL DX CW on 160.

Again thanks to Sinisa for causing me to play with the Hang and Decay settings. I had discovered the effect of Threshold myself but probably would not have tried such high settings for Hang if he had not made those posts. I've now had Orion nearly 6 months and am continuing to learn new things about how to use it properly! I also continue to learn more about K6STI's DSP Blaster which is a fantastic program IMHO.


Here is what Bill, W4ZV wrote to DL6FBL regarding the setting the AGC of the Orion 565 in the contest):
 
"I can say with certainty that Orion's default AGC Threshold settings are far too sensitive for 160. Threshold is set for 3 uV as default, and the lowest I ever had it in the CQ 160 was probably 30 uV, and sometimes higher. You can easily observe this by tuning to a quiet part of the band and adjusting Threshold to the maximum 192 uV. It will become very quiet (unless there is extremely high storm QRN) at 192 uV. You then adjust it down until the background noise is an acceptable level. [...] The AGC is the most different aspect of Orion and many guys have made the same mistake. [...] Orion really takes a little time to understand. [...] The manual is also at fault for recommending AGC settings for weak signals that are far too low for 160."
73, Bill W4ZV
 
Well, it is the recommendation by Bill, W4ZV. In the next article I will post the setting from European DX performers to compare it.
 
 
73, Petr OK1RP
...-.-

Thursday, June 27, 2019

Construction and design video-Beverage matching and termination by Steve, VE6WZ

Hi all,

An excellent "How to do" tutorial for low bands receiving Beverages antennas by Steve, VE6WZ can be found now on Youtube...

"A few weeks ago I uploaded a video on some design and construction ideas for Beverage matching and termination boxes. I show how to wind your own transformers, and present a few different enclosure methods.  I show how I have designed and built some commercially made double sided boards for broadside phase boxes and 4 Beverage switch boxes using KiCad and OSH park.

https://youtu.be/r85MqK_N3a8 

This video is part of my "RX antenna series” which includes various videos about low-band rx antennas.  It is still a work in progress and in a week or so I will add another video about installing Beverage wires in the field, and a video about beverage maintenance.

https://www.youtube.com/playlist?list=PLipJSm0KKo3BgY8F6NQ1DH3070C3SaUMN 
 
73, de steve ve6wz" 
 
(Published on: http://www.contesting.com/_topband - Topband Reflector)
 

Pondering other 160m transmit antenna by Rudy, N6LF

Pondering other 160m transmit antenna

I have tested several vertical antennas, feed against buried radials 0.1 lambda long. The wire vertical component or stacked pipes or even the real tower on the hill...

I have tested also very tall (>100 ft) tree at the edge of my property vertical with moderate results on Top Band. I’m thinking of using the tree to support the vertical component, and going to an elevated radial system.


Also the grounded half loop with 30/20m vertical sections and 80m phasing elements i tested for several years including the 16x 0.1 lambda long radials laying on the ground.

This is an interesting read about elevated radials:

https://rudys.typepad.com/files/elevated-ground-systems-article-final-version.pdf

(Thanks to Rudy, N6LF for that article...)


73 - Petr, OK1RP
.../-.-