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Re: LF: 137 ck

To: <[email protected]>
Subject: Re: LF: 137 ck
From: "Graham" <[email protected]>
Date: Tue, 9 Aug 2011 17:34:55 +0100
Importance: Normal
In-reply-to: <003201cc56ad$091bce90$0401a8c0@xphd97xgq27nyf>
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Power  corrupts  ..!
 
Yes that  is  probably  quantising   problems with the  a/d   conversations   , its quite a  big  step  response
 
Still worth  having a look  with the  audio-spec analyser for supply  components  , with  cheap (s/h) usb  sound cards , its a  cheap but  useful  test  instrument
 
Not sure  how a L/C  network  would handle  fast  keying ? was the  tx a  cw  beacon or  modulated  beacon ?  I use  
a  hex-fet series stabilised for  my 12v   20  amp  supply  and one of   2  500 watt  24v and  1.5 Kw  50 v  switch  mode  supplies  
 
Good  luck ..
 
73 -G..
 
 
 
 

Sent: Tuesday, August 09, 2011 4:57 PM
Subject: Re: LF: 137 ck

Graham
The display looks clean this end also the audio sounds pure with no 100 hz hum as monitored on an independent RX
I have the proper C's es L for decouping as per Decca instructions with this TX.
With a strong signal on some Grabbers there will be the dog bone effect with leading/trailing edge blips from keying carrier on/off
but on scope no transients visible.
73 de mal/g3kev
 
----- Original Message -----
From: Graham
Sent: Monday, August 08, 2011 11:49 PM
Subject: Re: LF: 137 ck

That's  the problem  with  modern   digital  technology , the  dynamic range  exceeds , that  of the  MK-1   eye  ball , 30 db is  1000:1  , will  show at  20 db over the  noise and  would  not  show on the  scope
 
Use a  reasonable   decoupling   capacitor  , and look at the  psu   voltage  using  a  (cheap) sound  card  (with high z resistive ladder for  safety) ..use  Wolf's   SPEC-LAB   to   view  the dB  attenuation  at  50, 100, 150 , 200  Hz  etc
 
Depending  on the  loop  bandwidth  of the  stabiliser , keying  may  also  induce  transits  , use the  peak  hold to  observe the  generated  spectrum
 
G..

Sent: Monday, August 08, 2011 8:29 PM
Subject: Re: LF: 137 ck

No hum Gary
I am monitoring on the scope and sig is vy clean
mal/g3kev
 
----- Original Message -----
Sent: Monday, August 08, 2011 8:19 PM
Subject: Re: LF: 137 ck

OK Mal,

Captures are at 10 minute intervals, but I have saved you going to SpecSavers as I have enlarged the frequency readout.

BTW...do you have some 100Hz hum on your transmission, look at my grabber to check.

73

Gary - G4WGT.


On 8 August 2011 19:28, mal hamilton <[email protected]> wrote:
Yes Gary
Your grabber seems to have a long delay before display es the times and freq hard to read
otherwise sensitivity seems ok at present for distance
73 de mal/g3kev
 
----- Original Message -----
Sent: Monday, August 08, 2011 7:21 PM
Subject: Re: LF: 137 ck

Mal,

You wrote.........While testing earlier find NO UK GRABBERS working

My 500kHz & 137kHz grabber runs 24/7....


Gary - G4WGT.


On 8 August 2011 18:33, mal hamilton <[email protected]> wrote:
Just finished my new PSU 60V/10A psu. While testing earlier find NO UK GRABBERS working and DK7FC has a SPURIOUS wobble signal right on 137.7
I will be QRV for a while from now on 137.7 qrs3 for DX qso's and will work locals on CW
73 De Mal/G3KEV
 






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