A third copy?
----- Original Message -----
From: "Sinisa Hristov" <shristov@ptt.yu>
To: <tentec@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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