2007 ARRL International EME Competition
11/26/2007 |
KL7UW
I have to respond to John, W8PAT's soapbox comments. I will write a more detailed report, later. John's comment about working Jim Larson WA0LPK (now AL7FS) leaves out the fact that I am the only full-time 2m EME station active in Alaska (nice to be popular when you run a peanut whistle station!). Other Alaskan's are active on 432 and above EME (KL6M occasionally works 2m).
The first few hours of Nov. 24 (starting at 0000z) the band above 144.100 had signals every KHz up beyond 144.150. This is the so-called "digital" sub-band for EME. Watching up to 50-KHz of band scope using the SDR-IQ makes this easy!
My stations consists of four M2 xpol-20 cross-polarity yagis (19.2 dBd array gain) mounted on a 50-foot tower. With them I can operate either with horizontal or vertical polarity. The four coax relay matrix permits receive and transmit polarity shifts independently. This came in very useful during this year's EME contest. I would guess that over 80% of my contacts involved operating with opposite polarity during Tx and Rx. One contact in the November weekend required the Tx polarity to be switched 3-times during the QSO as Faraday was changing more than at a minute rate.
With a super-low noise Preamp (0.15 dB) my system hears quite well and this is evidenced by the fact that W8PAT and I worked each other. His ERP is fairly matched to mine (slightly less antenna gain; over twice my RF power). I use a RFC 2-317 linear sspa that I squeeze 185w output by driving at 50w and running at 14.2 vdc (rated 170w/40w in). After 170-foot of 7/8-inch hardline this gives me 16.8 kW EIRP. This is 8-10 dB below the accepted minimum established for 2m eme (CW). So this is a real test of engineering and operating skill to make such a contact.
What makes this work is the 10-dB signal advantage that JT65B affords. Without the digital mode sw, I would not be able to make more than a handfull of contacts using CW. This year I made 32 contacts, 10 states, 14 countries for a score of 76,800. This is my personal best for an EME contest. Next time I will have my 8877 PA finished for much more signal! With QRO I will be able to tripple or quadruple my score!
One highlight was working LU1CGB in Argentina for country 32 and WAC 5 (still need Africa & Antarctica).
Yes! It was FUN! I'll post photos, later.
73- Ed
-- KL7UW
The first few hours of Nov. 24 (starting at 0000z) the band above 144.100 had signals every KHz up beyond 144.150. This is the so-called "digital" sub-band for EME. Watching up to 50-KHz of band scope using the SDR-IQ makes this easy!
My stations consists of four M2 xpol-20 cross-polarity yagis (19.2 dBd array gain) mounted on a 50-foot tower. With them I can operate either with horizontal or vertical polarity. The four coax relay matrix permits receive and transmit polarity shifts independently. This came in very useful during this year's EME contest. I would guess that over 80% of my contacts involved operating with opposite polarity during Tx and Rx. One contact in the November weekend required the Tx polarity to be switched 3-times during the QSO as Faraday was changing more than at a minute rate.
With a super-low noise Preamp (0.15 dB) my system hears quite well and this is evidenced by the fact that W8PAT and I worked each other. His ERP is fairly matched to mine (slightly less antenna gain; over twice my RF power). I use a RFC 2-317 linear sspa that I squeeze 185w output by driving at 50w and running at 14.2 vdc (rated 170w/40w in). After 170-foot of 7/8-inch hardline this gives me 16.8 kW EIRP. This is 8-10 dB below the accepted minimum established for 2m eme (CW). So this is a real test of engineering and operating skill to make such a contact.
What makes this work is the 10-dB signal advantage that JT65B affords. Without the digital mode sw, I would not be able to make more than a handfull of contacts using CW. This year I made 32 contacts, 10 states, 14 countries for a score of 76,800. This is my personal best for an EME contest. Next time I will have my 8877 PA finished for much more signal! With QRO I will be able to tripple or quadruple my score!
One highlight was working LU1CGB in Argentina for country 32 and WAC 5 (still need Africa & Antarctica).
Yes! It was FUN! I'll post photos, later.
73- Ed
-- KL7UW
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