Tuesday, 31 January 2017

RI1AND - new slot - 40m digi & low band RX experiments

I worked RI1AND on 40m JT65A a few days ago in the evening. Probably one of the easiest far DX that I remember. Walk in park!. Good signal here -11dB, consistent. He got back to me at the first call.

Over the last 3 weeks I have been doing some low band RX experiments.
I homebrew a half size K9AY, following F8AFC dimensions. I terminated with a 550ohm for 40m and the transformer was built with a FT140-43 and 8:24 turns - opposite windings.
I used JTDX JT65A+JT9 in SWL to listen to the bands over 24hrs and swap directions beaming East to West.
Then, I swaped to the inv V doublet [tuned to 40m] and listened in both 40/80m.

80m SWL JT65+JT9 - doublet antenna

Observations:
    - K9AY:
           - 3-4dB more noise beaming East than West [SDR]
           - definitely directive
           - NA blocked by the tall house behind my garden [due the ground installation]
           - Choke balun @ feedpoint or shack end did not help, if anything the opposite.
            - passed the 40dB common mode current disconnecting the loop vs. BC station
     - Doublet @ 11m apex seem to hear better than the K9AY.
     - Doublet tuned for 40m worked well as a RX 80m band
     - Many long DX spots follow nicely the sunrise/sunset enhancements [higher angle] per explanation in propagation chapter in ON4UN
     - SA is heard well in 40m... probably due to the slightly lower roof line and opening between 2 houses back of my garden.
     - I don't hear JA that well
     - Above 295deg West coast NA - nothing either!- aurora grilled.
     - ON4UN Low band DXing bible - best ham book I got and the absolute reference


107 countries heard in the last week


Last weekend I had a go at building the G3BJ receive antenna isolator, rather than buying the KD9SV system as I had originally planned.
The relay I found in my parts bag was not good and I have ended up "copying with pride" M0VKY implementation. Parts are now on its way and hopefully, I will be able to build it this weekend.


What next:
The K9AY and TX doublet will be in close proximity - within 5m. I want to check whether the mutual coupling leads to increased noise in the RX loop and how well the 2 work together in contest environment.
I will build a flag/pennant and compare with the other two. I am hoping that with the antenna being above the ground might listen better [less blocked signals] and nearby house QRN.

I found these experiments a well worth exercise to find out how well your station RXs. You can also compare the spots with other neighboring stations.

73 Angel  
M0HDF / M8A


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