Skip to main content

How low can you go

Have been busy to improve  receiving 137kHz  2200m.

I got DCF39  now 70dB s/n sometimes 75 dB  that's as strong as our MW Broadcast stations
1008 and 747kHz
Replaced the preamp IC by an LH005 op-amp tested some others
we have some real expensive low bias FET op-Amps at QRL  like the LH005 AD549 I could test
replacing the CA3041  some difference found in gain and IMD.
the OPA124p gave to much IMD possible to much gain
The best performer was the LH005  having not to much gain in the used ciquit.

Found the K9AY is not good enough  for this bandThe inverted-L gives best s/n
trying to decode  WE2XGR at 137.700  last night
had the best receiving results until now.

TimestampCallMHzSNRDriftGridPwrReporterRGridkmaz
 2012-12-07 06:16  GV7FTX  0.137688  -26  0  QG75  0.1  PA0O  JO33hg  15870  329 
 2012-12-07 00:40  G8HUH  0.137617  -24  0  IO81mg  0.05  PA0O  JO33hg  688  67 
 2012-12-07 01:28  DF6NM  0.137580  -8  0  JN59nj  0.5  PA0O  JO33hg  532  326 
 2012-12-07 20:22  G1SLE  0.137543  -22  0  IO93if  0.02  PA0O  JO33hg  526  86 
 2012-12-06 23:30  DK7FC  0.137620  0  0  JN49ik  1  PA0O  JO33hg  450  342 
 2012-12-06 22:28  PA0A  0.137500  +9  0  JO33de  0.5  PA0O  JO33hg  24  67 

GV7FTX is a ghost decode that can happen sometimes with interference  
first time received G8HUH  many decodes
and DK7FC  several +4dB decodes
but no WE2XGR seen yet
There are 3 strong 137kHz signals Worldwide
DK7FC  PA0A  and  WE2XGR
Dk7FC  was decoded in USA last night!
It  is not a band for QRP  and small antenna's

ZL9HR  no more QSO's   tried RTTY 30M  even there was police and deliberate QRM
80m never heard  anything else but tuners and QRI
Should have been easy 30m cw  but when in the shack they are somewhere else
or just stopped 30 and qsy to some band that is not open for us
Propagation was not favourite this week
Only tonight  again WSPR 80m  VK7DIK was back in



Comments

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

TS790 cat interface

A CAT interface  for the old TS790 144/432/1292 tranceiver to work with N1MM  including the internal CW keyer DTR and "PTT" RTS and WSJT MSHV with "PTT" control Using the 3€ FTDI USB serial interface picture bottom page first i bought the Kenwood USB serial interface cable that cable has the TS790 special 6 pin DIN plug this interface works well ...as long as you cut the 4-5  wire bridge on the ACC din.. with the wire bridge it did go offline after 30 seconds or so  Kenwood interface cable with CH330 eBay 15€    This type Kenwood interface cable uses a tiny 6 pin USB CH330 chip  The driver is CH340 known for Arduino it workes in W7/10 64  It has only TX RX Usart function no DTR RTS available  The TS790 settings are 4800b 8bit data 2 stop  default  N1MM does not list the TS790 it has the TS890  but that one does not support modes the TS2000 does support freq and modes and let you switch 2/70/23 it seem...
4 comments
Read more