[TenTec] A test of Orion's external CW keying

Steve Baron - KB3MM SteveBaron at StarLinX.com
Fri Feb 27 03:35:24 EST 2004


A third copy?

----- Original Message ----- 
From: "Sinisa Hristov" <shristov at ptt.yu>
To: <tentec at contesting.com>
Sent: Friday, February 27, 2004 03:10
Subject: [TenTec] A test of Orion's external CW keying


> A test of Orion's external CW keying
>
>
>
> [Please read using a fixed with font such as Courier New.]
>
>
>
> Introduction
> ============
>
> TenTec's Orion is being described as having state-of-the-art CW keying.
> ARRL's "Product Review" and "Expanded Test-Result Report" both contain
> a scope printout indicating severe and varying pulse shortening.
> This text describes a series of more detailed measurements proving
> that keying pulse is being shortened by a significant and randomly
> varying amount.
>
> Readers not interested in details may want to skip
> directly to "Discussion" below.
>
>
>
> Setup
> =====
>
>  1. TenTec Model 565 Orion S/N 10C10083
>       firmware version = 1.369 (Master Reset performed after loading)
>       set power level  = 40 W  (due to attenuator ratings)
>       30 minutes warm-up with intermittent transmitting
>       no controls were touched during measurements
>       SWEEP off, freq =  7010 kHz
>       internal keyer off  (note: "CW Weighting" control does not affect
external keying)
>       front panel CW jack:
>         open circuit voltage  = 4.19 V
>         short circuit current = 407  uA
>         Rinternal             = 10.3 kOhm
>
>   2. Agilent 33120A Function/Arbitrary Waveform Generator
>        Rout = 50 Ohms
>        amplitude = 2.5 Vpp into 50 Ohms (5 Vpp open circuit)
>        offset    = +1.25 V into 50 Ohms (2.5 V open circuit)
>        shape = square, duty cycle = 50 %
>        burst mode:  count = 1, phase = 180 deg
>        this provides a perfect keying waveform
>        with independently adjustable period and pulse width
>
>   3. Narda 776B-30 Attenuator (50 W CW, 30 dB, 18 GHz)
>
>   4. Tektronix TDS 3054 Digital Phosphor Oscilloscope (500 MHz, 5 Gs/s)
>
>
>
> Procedure
> =========
>
> Keying signal from 33120A was applied to Orion's front panel jack.
> Both the keying signal and the attenuated RF output signal
> were observed and recorded using TDS 3054. Timing points for
> the RF pulse width measurements were set at 50 % envelope amplitude.
>
>
>
> Results
> =======
>
>
> Test 1:  Delay and pulse width
> ------------------------------
>
> "CW Rise/Fall" control = 5 ms
> keying pulse width     = 20.833 ms ("dit" duration at 60 wpm)
>
> For each row in the table a number of pulses were issued
> until the steady state was reached (it could take a couple of minutes)
> and then 25 measurements were performed and results noted.
>
> keying                                                 RF       observed
> pulse   "dit"   CW QSK     leading     trailing       pulse      pulse
> rate    rate    delay    edge delay   edge delay      width    shortening
> [Hz]    [wpm]    [%]        [ms]         [ms]         [ms]        [ms]
> -------------------------------------------------------------------------
>   2       5        0     20.6-27.1    14.2-19.6     9.6-16.6    4.2-11.2
>   2       5      100     22.4-28.4    14.3-19.9     7.5-15.7    5.1-13.3
> -------------------------------------------------------------------------
>  10      25        0     22.6-25.3    14.6-18.6    12.1-15.7    5.1-8.7
>  10      25      100     22.6-25.2    15.0-19.3    10.6-16.1    4.7-10.2
> -------------------------------------------------------------------------
>  24      60        0     25.9-29.9    14.6-17.6     7.4-11.9    8.9-13.4
>  24      60      100     26.2-29.0    13.9-17.3     7.3-11.9    8.9-13.5
> -------------------------------------------------------------------------
>
>
> Corresponding averages and standard deviations are:
>
> keying                                                 RF       observed
> pulse   "dit"   CW QSK     leading     trailing       pulse      pulse
> rate    rate    delay    edge delay   edge delay      width    shortening
> [Hz]    [wpm]    [%]        [ms]         [ms]         [ms]        [ms]
> -------------------------------------------------------------------------
>   2       5        0     23.3, 1.3    17.2, 1.6    14.4, 2.3    6.4, 2.3
>   2       5      100     24.2, 1.5    17.0, 1.4    13.3, 3.0    7.5, 3.0
> -------------------------------------------------------------------------
>  10      25        0     24.0, 0.6    15.9, 1.1    12.8, 1.0    8.0, 1.0
>  10      25      100     23.8, 0.8    16.8, 1.4    13.9, 1.4    6.9, 1.4
> -------------------------------------------------------------------------
>  24      60        0     27.9, 1.1    16.3, 0.9     9.4, 1.5   11.4, 1.5
>  24      60      100     27.6, 0.7    15.6, 1.0     9.0, 1.8   11.8, 1.8
> -------------------------------------------------------------------------
>
>
> Test 2:  RF Rise and Fall Times
> -------------------------------
>
> keying pulse width = 20.833 ms ("dit" duration at 60 wpm)
>
> For each row in the table a number of pulses were issued
> until the steady state was reached (it could take a couple of minutes)
> and then a single measurement was performed and results noted.
>
>                                          RF     RF
> pulse   "dit"   CW QSK   CW Rise/Fall   rise   fall
> rate    rate    delay      setting      time   time
> [Hz]    [wpm]    [%]        [ms]        [ms]   [ms]
> ----------------------------------------------------
>   2       5        0         3          0.26   1.5
>   2       5        0         5          0.38   3.0
>   2       5        0        10          0.38   3.0
> ----------------------------------------------------
>   2       5      100         3          0.24   1.5
>   2       5      100         5          0.38   3.0
>   2       5      100        10          0.38   3.0
> ----------------------------------------------------
>  10      25        0         3          0.46   1.5
>  10      25        0         5          0.75   3.0
>  10      25        0        10          0.75   3.0
> ----------------------------------------------------
>  10      25      100         3          0.46   1.5
>  10      25      100         5          0.75   3.0
>  10      25      100        10          0.75   3.0
> ----------------------------------------------------
>  24      60        0         3          1.6    1.5
>  24      60        0         5          3.0    3.0
>  24      60        0        10          3.0    3.0
> ----------------------------------------------------
>  24      60      100         3          1.6    1.5
>  24      60      100         5          3.0    3.0
>  24      60      100        10          3.0    3.0
> ----------------------------------------------------
>
>
>
> Discussion
> ==========
>
>
> Test 1:  Delay and pulse width
> ------------------------------
>
> Orion performs a randomly varying shortening of the CW RF pulse
> relative to the CW keying pulse. Shortening values from 4.2 ms
> to 13.5 ms were observed. The ARRL's scope printout indicates
> shortening of 8.9 ms for the "first dit" and 12.1 ms for the
> "second dit", which is in agreement with my results. No substantial
> difference was found between 0 % and 100 % "CW QSK delay" settings.
>
> According to observed values, the keying waveform with a perfect
> 1:1 dit/pause ratio will be distorted as follows:
>
>   CW speed   dit time   dit/pause ratio
>     [wpm]      [ms]      [1 : value]
>   -------------------------------------
>      25        50.0      1.18 - 1.74
>      30        41.7      1.22 - 1.96
>      35        35.7      1.27 - 2.22
>      40        31.3      1.31 - 2.52
>      45        27.8      1.36 - 2.89
>      50        25.0      1.40 - 3.35
>      55        22.7      1.45 - 3.93
>      60        20.8      1.51 - 4.70
>
> It is recommended to make all keying pulses longer by approximately 9 ms,
> at the expense of the following pause (I think WriteLog can do it).
> Doing so will "center" the RF pulse width at the desired CW pulse width,
> although random variations will still remain.
>
>
> Test 2:  RF Rise and Fall Times
> -------------------------------
>
> Observed RF rise and fall times were found to be much shorter
> than the "CW Rise/Fall" menu setting.
>
> The leading edge of the RF pulse is "chopped off" and will produce
> strong "clicks". This effect is reduced with a continuos stream of "dits".
>
> No substantial difference was found between 0 % and 100 % "CW QSK delay"
settings.
>
>
>
> Various other findings
> ======================
>
> * Oscillating artefacts were observed in the rising edge.
>   Three scope screens were dumped to TIFF files and will be
>   emailed to interested parties.
>
> * S meter has indicated the power as either 0, 15 or 60 W,
>   although the scope reading did not change at all between
>   those three indications.
>
>
>
> 73,
>
> Sinisa  YT1NT, VA3TTN
> _______________________________________________
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> TenTec at contesting.com
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>



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