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RE: Cheap and nasty sources - was LF: DK7FC WSPR bad quality problem

To: <[email protected]>, <[email protected]>
Subject: RE: Cheap and nasty sources - was LF: DK7FC WSPR bad quality problem
From: "Clemens Paul" <[email protected]>
Date: Sun, 27 Mar 2016 20:47:55 +0200
In-reply-to: <[email protected]om>
References: <[email protected]om>
Reply-to: [email protected]
Sender: [email protected]
Thread-index: AdGIU3zsUb0S9Ty6QfmkCoFrAZJV5AAAo+OA
Hello all,

I've been watching the 100Hz sideband WSPR multi-decodes also from the other 
two strong stations on MW,
DH5RAE and DB0ABR.They are located about 65km from me and generate  S9++dB 
signals here.
The deoded sidebands are also about 40dB down.
DB0ABR has tried a different power supply to no avail and both believe that the 
DDS synthesizer is the culprit.
It is a AD9859,see
http://www.dj0abr.de/index_english.html
I have added a perseus screenshot with a bin width of 0.24Hz showing strange 
lines in their signal.
I'm not sure if this is the DDS spectrum what we see here.

73
Clemens
DL4RAJ 



>-----Original Message-----
>From: [email protected] 
>[mailto:[email protected]] On Behalf Of Andy Talbot
>Sent: Sunday, March 27, 2016 8:06 PM
>To: [email protected]; [email protected]
>Subject: Cheap and nasty sources - was LF: DK7FC WSPR bad 
>quality problem
>
>It is unfortunate these cheap and simple low power solutions 
>have come-about at all.   The originators who worked out how 
>to generate a few milliwatts of Rf from very non-purpose 
>designed hardware presumably never anticipated that eh great 
>masses would end up connecting this unsuitable kit to high 
>power amplifiers.    I hope they only ever anticipated their 
>being used for very low power uses.
>
>As for the R-PI, that really does look like a bad way of 
>generating narrow band RF.     I don't know the details of its 
>internal hardare, but strongly suspect that it uses a 
>jittering   Fract-N route to generating arbitrary frequencies. 
>  Again, fine for a few milliwats of test signal, but 
>certainly not for amplification to hundreds of milliwatts.
>
>If you want a decent high power source, use a DDS chip  or a 
>modern Fract-N synthesizer like the LMX2541.  That device has 
>an internal VCO and an output divider that allows it to 
>generate as low as 35MHz - and then any external CMSO divider 
>will allow you to go lower.   And they are CLEAN - especially 
>so when divided down to LF / HF 
>
>
>Andy  G4JNT
>
>
>
>
>On 27 March 2016 at 18:14, Graham <[email protected]> wrote:
>
>
>       
>       Andy,
>        
>       This time its not really Stefan's  fault  :-,)
>        
>       This is a  problem , using the  raspberry PI ,  the  Pi 
>processor uses  interrupts, which, cause the  execution  time  
>of the  timing  loops to  vary  slightly ,
>       the 'small' time  variations , produce side bands .
>        
>       This was evident  during  the  development of  a  R-PI  
>routine  for  sending  Opera , as the  R-Pi support 
>documentation is not  particularly  comprehensive, its  'not' 
>possible to  fully address the  i/o  functions and as such 
>there exists  a conflict  with higher order irq   requests .  
>Producing  seemingly  random widening  of the  spectrum,  
>depending  on the  irq  deployments. 
>        
>       Ie the  pulse train suffers  from  timing  jitter 
>        
>       The  alterative of the  U3 beacon  key'er , driving  
>the  DDS 'oscillator' is  a more  elegant  solution,  but as 
>noted by  Andy [rad-com]  some time  back, the  later  U3 with 
>the  PPL  suffers from  settling  time issues ,  when  
>commanded with , step  frequency changes.  these sever to 
>produce sidebands , at the  step changes. 
>        
>       73-G, 
>        
>
>       From: F6CNI - Andy - JN19QB <mailto:[email protected]>  
>       Sent: Saturday, March 26, 2016 8:36 PM
>       To: RSGB LF Group <mailto:[email protected]>  
>       Subject: LF: DK7FC WSPR bad quality problem
>
>
>       Hello Stefan.
>
>        
>
>       I am sorry, but this evening you have a very poor 
>quality WSPR signal on MF with many splatters, I think it is 
>perhaps due to an overload TX AF level.
>
>        
>
>       That is not in phase with the normal ham spirit. So, 
>please be kind to stop now your transmission and correct this problem.
>
>        
>
>       On the way, can you say honnestly if your power is not 
>over the legal limit ?
>
>        
>
>       Sincerly yours and  my best 73 de Andy.
>
>        
>
>       P.S. 
>
>        
>
>       Have a look below at some reports last hour showing the 
>problem :
>
>        
>
>        
>
>2016-03-26 19:00 
>
>DK7FC 
>
>0.475683 
>
>+12 
>
>0 
>
>JN49ik 
>
>1 
>
>PI4THT 
>
>JO32kf 
>
>336 
>
>338 
>
>2016-03-26 19:00 
>
>DK7FC 
>
>0.475783 
>
>-25 
>
>0 
>
>JN49ik 
>
>1 
>
>PI4THT 
>
>JO32kf 
>
>336 
>
>338
>
>2016-03-26 18:50 
>
>DK7FC 
>
>0.475783 
>
>-23 
>
>0 
>
>JN49ik 
>
>1 
>
>PE1RKT 
>
>JO22fb 
>
>418 
>
>316 
>
>2016-03-26 18:50 
>
>DK7FC 
>
>0.475683 
>
>+14 
>
>1 
>
>JN49ik 
>
>1 
>
>PE1RKT 
>
>JO22fb 
>
>418 
>
>316
>
>2016-03-26 18:40 
>
>DK7FC 
>
>0.475683 
>
>+12 
>
>0 
>
>JN49ik 
>
>1 
>
>LA8AV 
>
>JO59cs 
>
>1153 
>
>4 
>
>2016-03-26 18:40 
>
>DK7FC 
>
>0.475783 
>
>-24 
>
>0 
>
>JN49ik 
>
>1 
>
>LA8AV 
>
>JO59cs 
>
>1153 
>
>4 
>
>2016-03-26 18:50 
>
>DK7FC 
>
>0.475783 
>
>-28 
>
>0 
>
>JN49ik 
>
>1 
>
>LA3JJ 
>
>JO59bh 
>
>1102 
>
>4 
>
>2016-03-26 18:50 
>
>DK7FC 
>
>0.475683 
>
>+10 
>
>0 
>
>JN49ik 
>
>1 
>
>LA3JJ 
>
>JO59bh 
>
>1102 
>
>4 
>
>2016-03-26 18:40 
>
>DK7FC 
>
>0.475780 
>
>-28 
>
>1 
>
>JN49ik 
>
>1 
>
>G3KEV 
>
>IO94sh 
>
>829 
>
>314 
>
>2016-03-26 18:40 
>
>DK7FC 
>
>0.475679 
>
>+10 
>
>0 
>
>JN49ik 
>
>1 
>
>G3KEV 
>
>IO94sh 
>
>829 
>
>314 
>
>2016-03-26 19:10 
>
>DK7FC 
>
>0.475682 
>
>+13 
>
>0 
>
>JN49ik 
>
>1 
>
>F6CNI 
>
>JN19qb 
>
>389 
>
>266 
>
>2016-03-26 19:10 
>
>DK7FC 
>
>0.475782 
>
>-27 
>
>1 
>
>JN49ik 
>
>1 
>
>F6CNI 
>
>JN19qb 
>
>389 
>
>266 
>
>2016-03-26 18:30 
>
>DK7FC 
>
>0.475682 
>
>+15 
>
>0 
>
>JN49ik 
>
>1 
>
>F5WK 
>
>JN18hp 
>
>452 
>
>261 
>
>2016-03-26 18:30 
>
>DK7FC 
>
>0.475782 
>
>-22 
>
>0 
>
>JN49ik 
>
>1 
>
>F5WK 
>
>JN18hp 
>
>452 
>
>261 
>
>2016-03-26 18:00 
>
>DK7FC 
>
>0.475680 
>
>+19 
>
>0 
>
>JN49ik 
>
>1 
>
>DL6II 
>
>JO30nx 
>
>205 
>
>327 
>
>2016-03-26 18:00 
>
>DK7FC 
>
>0.475780 
>
>-18 
>
>0 
>
>JN49ik 
>
>1 
>
>DL6II 
>
>JO30nx 
>
>205 
>
>327 
>
>2016-03-26 18:50 
>
>DK7FC 
>
>0.475682 
>
>+17 
>
>0 
>
>JN49ik 
>
>1 
>
>DL4RAJ/2 
>
>JN68kj 
>
>326 
>
>109 
>
>2016-03-26 18:50 
>
>DK7FC 
>
>0.475782 
>
>-22 
>
>0 
>
>JN49ik 
>
>1 
>
>DL4RAJ/2 
>
>JN68kj 
>
>326 
>
>109
>
>        
>
>
>

Attachment: DH5RAE+DB0ABR.png
Description: PNG image

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