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Eme


#1

Anyone done an EME activation yet? Doesnt look that hard on 70CM.

Compton


#2

No that hard as long as the Chaser station owns something similar to Joderell bank! Or are you talking just JT-65 ?

Ed.


#3

JT65 qualifies it. Cant be that hard…


#4

Seems like a technically challenging problem. Among the issues:

  1. Keeping time accurate enough. This can probably be done using normal methods (Dimension 4 on a PC, connected to a WiFi hotspot via a smartphone, though I wonder how well this would work).

  2. You’ll need a good amount of amplification. At 70cm, probably 100-200 watts PEP, with a really good sized yagi. The antenna would probably be a long boom yagi, or a couple long boom yagis that you can aim and adjust the polarization by hand.

  3. The amplification means you’ll need batteries. Enough for several one-minute-long T/R cycles on JT-65. With each contact taking roughly 6-7 minutes, and half of that transmitting, and then multiplied by 4 (for 4 QSOs)–that’s a lot of power. If you’re carrying batteries, you’ll need a multiple of the battery capacity of that to keep everything powered.

  4. You’ll need a location where you can haul all of this trash to. It’s a lot of stuff, and heavy!

  5. You’ll need to make the best use of ground gain, so, actually, a small hill with a clear, very flat view to the moon for as far as the eye can see is desirable.

  6. Your radio will need a nice TCXO or OCXO to keep the frequency as stable as possible.

  7. You’ll need to correct for dopplar shift, which is very significant at 70 cm.

  8. Most EME skeds are coordinated over a chat room, so you’ll probably want your computer connected to that.

  9. The computer would need to be running: Dimension 4, a CAT program, WSJT-X, and a chat program for the sked, minimally.

  10. EME conditions would have to be pretty damn good.

  11. You’ll need to find some EME & SOTA Enthusiasts. I’m sure they’re out there, but I wonder how much overlap there is in that Venn Diagram.

This looks like a great challenge, though. I’d like to assist if I can–I don’t do EME but I am a Goat, and VHF/UHF operating is very interesting to me.

73
Nate N0PCL


#5

It’s more than feasible but…

  • needs a small team at activation end to carry and operate
  • 70/23 probably best bands due to antenna size
  • have to be JT65 or similar due to ERP likely available under SOTA rules
  • team need to practice using setup a good few times before trying on a summit
  • may help to try when some EME event on more big stations to work
  • maybe worth arranging with some big stations to practice with

Tempting…