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Re: [TenTec] Orion AM RX Performance Measurements

To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] Orion AM RX Performance Measurements
From: "Ron Castro" <ronc@sonic.net>
Reply-to: Ron Castro <ronc@sonic.net>,Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Sat, 18 Mar 2006 09:09:04 -0800
List-post: <mailto:tentec@contesting.com>
Sinisa:  Great information!  Was this on an O1 or O2?  In AM, even with the 
AGC settings you describe for low distortion, I still hear significant 
distortion on the voice peaks on stable, ground-wave commercial broadcast 
stations.  Right now, I am hearing it on ABC's KGO, San Francisco.  I 
realize that broadcast stations use significant amounts of clipping in their 
processing, but this is more than what I hear on my car radio or on my 
TS-870.

The results of you test confirm my suspicion that the AGC is peak-detecting, 
not RMS controlling, which would account for the S-meter varying with 
modulation, which is not the case on any AM receiver I have seen before, 
including the '870.  But even with the AGC turned off, and the RF Gain 
control turned to run the S-meter above the peak level of the station, I can 
hear the distortion on the peaks.  Must be a DSP thing.

Ron
N6AHA

----- Original Message ----- 
From: "Sinisa Hristov" <shristov@ptt.yu>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, March 18, 2006 8:37 AM
Subject: [TenTec] Orion AM RX Performance Measurements


>A fixed width font is recommended to view the data correctly.
>
>
>
> Part One - Total Harmonic Distortion
> ====================================
>
>
> Main RX, 3750 kHz, AM
> PREAMP OFF, ATTN OFF, RF GAIN 100
> ROOF 20 kHz, BW 6000 Hz, PBT 0 Hz
> modulation freq = 300 Hz, modulation depth = 50 %
> carrier level = -53 dBm (S9 + 20 dB)
> measured at speaker output with external 4 Ohm speaker connected
>
>
>          Total Harmonic Distortion
>                 in Percent
>
> HANG  dB/s    1.373b5   2.056
> -----------------------------
> 0.3      5      0.41     0.44
> 0        5      1.27     0.65
> 0       50      4.8      3.1
> 0      100      8.0      5.8
> 0      200     13.4     10.5
> 0      500     24.5     21.4
> 0     1000     35       35
>
> Orion can deliver up to 1.4 W into 4 Ohm load with
> less than 0.5 % THD, using HANG of 0.3 seconds and 5 dB/s.
>
> This is a static mesurement in laboratory conditions.
> On the air performance seems to be affected a lot by selective fading.
>
>
>
> Part Two - Frequency Response
> =============================
>
>
> Sub RX, V2.056, 900 kHz, AM 50 %, BW 6000 Hz.
> measured at speaker output with external 4 Ohm speaker connected
>
>
> Frequency Response in dB
>
>         PBT setting
> freq    0 Hz   1200 Hz
> ----------------------
> 400    0.0     0.0
> 500   -0.1    -0.1
> 600   -0.2    -0.15
> 700   -0.35   -0.3
> 800   -0.5    -0.45
> 900   -0.7    -0.55
> 1000   -0.9    -0.75
> 1100   -1.0    -0.9
> 1200   -1.2    -1.05
> 1300   -1.4    -1.2
> 1400   -1.5    -1.35
> 1500   -1.7    -1.45
> 1600   -1.8    -1.55
> 1700   -1.9    -2.1
> 1800   -2.0    -5.9
> 1900   -2.05   -7.7
> 2000   -2.1    -7.6
> 2100   -2.2    -7.7
> 2200   -2.25   -7.7
> 2300   -2.3    -7.7
> 2400   -2.3    -7.7
> 2500   -2.3    -7.7
> 2600   -2.35   -7.7
> 2700   -2.35   -7.8
> 2800   -2.35   -7.8
> 2900   -3.15   -7.8
> 3000  -12.6    -7.8
> 3100   none    -7.7
> 3200   none    -7.7
> 3300   none    -7.6
> 3400   none    -7.5
> 3500   none    -7.4
> 3600   none    -7.3
> 3700   none    -7.2
> 3800   none    -7.05
> 3900   none    -6.95
> 4000   none    -6.9
> 4100   none    -7.6
> 4200   none   -17.1
>
>
> An attempt to shift PBT by 1200 Hz in order to obtain wider response,
> results in response being DOWN by almost 6 dB from 1850 Hz up.
> The weakened response continues up to 4.1 kHz.
>
>
>
> Part Three - Equipment used
> ===========================
>
>  HP 33120A Function Generator
>  R&S SME 03 Signal Generator
>  Amber 3501A Distortion & Noise Measurement System (True RMS)
>  TDS 3054 Oscilloscope
>
>
>
> 73,
>
> Sinisa  YT1NT, VE3EA
>
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> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
>
> 

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