Skip to main content

Keeping the noise floor clean. WSPR with the FLEX1500


USB -serial converters  can rise the local noise level  by 3- 6dB.
General eliminating digital originated noise is  much more important then using a low noise pre-amp of course. A low noise pre-amp is made useless by this noise. 

If the USB-serial is just plugged in without any RFI protection it can spoil the noise floor on higher bands like 50MHz  and others ( i did not test yet 70)
But I noticed  a serious  noise increase when starting the logger program.
Also a intermittent noise burst effect 1/ second can be noticed. This noise burst runs synchronised with the data string over the serial port.  
When starting N1MM CAT communication over the USB-serial the base noise clearly came up
3-6dB   Then  using the big toroid and a better shielded USB cable it was better.
It is tricky this USB-serial chip noise because it will not stop immediate after closing the CAT communication. It will hang in  some 5-10 seconds before the USB device steps to lower activity.
I noticed this before using Winkeyer-USB some years ago.
Also using  a USB  sound-device is not without RFI consequences.
This  also could have blurred the weak JA signals last Saturday.
--------------------------------------------------------------------------

The FLEX1500
I am using it for WSPR  again on 477 and 500kHz  3.5MHz   28MH.


 It is working fine again  over USB2 Lenovo W510.
No audio-streaming hicks noticed.
CPU % 5-18
I now have the latest version P-SDR 2.3.5
I did not check whether XVTR SPLIT bug is fixed. I did not see it in in the bug fix list. 

For  WSPR the Flex1500 is real nice  I can  select a separate RX  antenna  the K9AY if needed.


This Flex1500 was just spotted by big ears VK7DIK !
 2012-07-23 20:12  PA0O  3.594126  -25  0  JO33hg  5  VK7DIK  QE28sf  16731  84

Good, now I have the K3 free for other things.


One other thing I noticed.
The errors in the CAT  connection N1MM -K3    I had this again few times    Also when logging
JA0RUG at 50MHz ....I had to reset / restart N1MM  to be able to log again.  Of course this will happen preferably at such prime time moment.  Suddenly  call entry was whipped out and the frequency ruler displayed wild out of band showing red zone.
This problem seems to be related with Telnet.  When I closed the Telnet box in N1MM the connection was stable again.



Comments

Unknown said…
Great work i am very impressed by your information.
Thank you for sharing.

Polystick


October 15, 2012 at 2:15 PM
Post a Comment

Archive

Show more

Popular posts from this blog

2011-01-22 DIAMOND 2m 70cm 1m30 Colinear inside

Having relative poor signals on the local 70cm / 2m channels using this X50 Diamond collinear 70/2  1m antenna at a height of 25m. I needed to investigate what could be wrong. Measuring the cable only 3W is left for the antenna of the 10W 435MHz output from a IC451E The cable is 30m type H100 Z50 10mm outside diameter it is semi air-spaced but has an impossible 4mm² solid CU inner conductor not much air left. I preferred the H43 Z75 cable having lower loss and mechanical better ratio in conductor size. My antenna uses SO239 connector UHF type semi air spaced isolator.  3W should be enough for a comfortable noise free FM signal. But only 27km away at PA0A the signal is weak too weak something must be wrong? I made a simple reference dipole of 2x17cm CU wire. With this dipole the signals where totally worse. So the Diamond does work? I got curious to look inside. Maybe moisture penetration degraded the antenna. This  antenna is rainwater close in its n...
8 comments
Read more

SPF5189z Low noise preamp 23cm

 14-4-2018 updated Above the low noise  preamp 50 - 4GHz    ebay  6€ Tested  2 small porto antennas 1 Baofeng UV antenna left   2nd best signal on PI2NOS 2 eBay DIAMONDSRH805S  wide band 144/432/1200  it works for its size as expected 3 piece of wire :   best signal in the setup... Unit under test at workbench. It was stable  50mA  at 5V   few days,  but sudden the current went up to 100mA And i could  no longer adjust it with the negative bias Voltage. The - Voltage went to zero and the SPF input port became low Z. This SPF5189z was broken  no oscillations, no input overload just it broke while i was receiving the PI2NOS 430.125 using a small antenna at the workbench. The specs of  SPF5189z  say it has an internal circuit  regulating the bias current. Replaced . again   with an other of the 5 spare SPF i have. The new one again could be adjuste...
11 comments
Read more

BIJZEN mast en ontwerp fouten.

In 2013 heb ik een Bijzen aluminium mast 3 x7m  opgehaald  bij iemand die hem niet mocht plaatsen Gemeente Oss  dat zegt misschien al genoeg.. Pas in 2018 heb ik hem geplaatst had ik veel eerder moeten doen. Mooie mast, mijn xyl vond hem zelfs mooi. Hij is licht, de 3 delen wegen  235kg  het vaste deel 102kg dus het te lieren gedeelte weegt   slechts 133kg + ca 50kg rotor + antennes etc.  De elektrische lier is wel erg zwaar 30kg misschien wel maar die zit onder    Antenne  3ele Steppir  19kG  +  G2500DXC rotor: 3.6kg  + rotorbuis 12 kg  +  kabels 10kg  + 5/7 ele 6m beam. ongeveer 50kg Je moet niet te dichtbij  kijken, dan valt op dat het Aluminium lastwerk heel slordig is gedaan, scherpe bramen aan de lassen waar kabels door kunnen worden beschadigd of haken Er is zeer ! weinig ruimte voor de rotor een YAESU G2500DX past net maar dan ook net  met beetje buigen van  kruisverband. Het...
3 comments
Read more