[Lowfer] OMG....VK4YB decoded

[Don Merz]

I'd be interested in hearing more about your transformers.73, Don Merz, N3RHT


      From: Michael Sapp <wa3tts at verizon.net>
 To: John Langridge <kb5njd at gmail.com> 
Cc: lowfer at mailman.qth.net
 Sent: Tuesday, April 25, 2017 10:08 AM
 Subject: [Lowfer] OMG....VK4YB decoded
   
John & All:  Rather astonishing decode this morning on my NW EWE antenna which is my lowest background noise direction pointed at 300 degrees, VK4YB at -26 1006 UTC.  Bearing to VK4YB is 270 degrees, so there is only 1/2~1 dB difference versus middle of main lobe on the EWE cadio pattern.

No WH2XCR decodes overnight which seems strange, so perhaps a different propagation mode or reflection angles and iono height. I was thinking I might have a chance of an XCR decode overnight with the lower QRN and post geomag quiet conditions.  

https://www.dropbox.com/s/1iejrh8p2tmq8kt/DISTANCE.JPG?dl=0

But only VK4YB and XGP for best overnight DX....

Last week I did change over to a new pair of antenna matching transformers on my other NE/SW EWE which is more or less orthogonal..  I had a pair of larger type 75 core binocular transformers on the NE/SW antenna which had low loss (1dB range) at 10 kHz.  Anyway, I had been concerned about system imbalance and the potential effect on common-mode noise ingress,  so I went back to the same transformer design used in the NW/SE EWE antenna which I decoded VK4YB on overnight.  

That transformer design is a set of 4 BN73-202s glued together end to end which are 3T/10T.  The back-to-back insertion loss was very low and was difficult to measure with high accuracy at the time (2013).  A the time I only had a Wavetek signal generator and CA-91 RF voltmeter and back-to-back transformer insertion loss was around .1dB for the pair as far as I could tell.  I will have to make some measurements with my HP3586c over the weekend and make a better determination of the insertion loss on the 4-core BN73-202 transformers.  I also want to IMD test those transformers as well, but that takes a bit more effort....

Once I have some solid and recent data, I will elaborate more on the antenna transformers if there is interest.  That was the only recent change to the antenna system here. There is a chance my common mode noise situation improved slightly, or there may be no change at all. It's to early to say.  The VK4YB decode could be just a fluke of propagation and local weather  and not anything I did on this end of the communication link hardware...


73 Mike wa3tts





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