[VHFcontesting] 6m, 2m, 70cm EME

Mon Sep 30 06:46:10 EDT 2024

 Hi Scott,I'll "do the maths" on-list and ask questions direct as they occur to me. :-)
For your recent QRP 432 EME, I calculate...
~75watts as +49dbm30' of terminated FSJ1-50 at -2DBCuscraft 424B at +16 dbiGround refelection at +3dB (no elevation control)

System ERP = ~65 dBm EIRP
Thanks!  This is giving me a range-of-operation to ponder in my thought experiment.
Ev, W2EV

    On Sunday, September 29, 2024 at 01:55:29 PM EDT, Scott Armstrong <aa5am.scott at gmail.com> wrote:  

 Hi Ev,

About 9 years ago I was playing around on 144 MHZ EME with a single yagi
until a lightning strike did me in.
I made 20 initials at that time and heard/decoded (JT65b) many more.

The equipment was a 30+ year old Microwave Modules transverter (drifted
quite a bit), Mirage Amp ~150W, 80-90 feet of RG213 and a single, beat up,
Cushcraft 4218XL at 18ft with no elevation.  Also did not have a preamp in
the system.
 Rough calculations shows that the system had an EIRP of about 8.2kW

More recently I have worked Bernd, DL7APV and Frank, NC1I on 432 MHz.
Haven't tried with anyone else.
The station consisted of  a IC9700  ~75W using about 30 feet of FSJ1-50 to
a  single, beat up, Cushcraft 424B at 6ft with no elevation. Only preamp in
use was the one internal to the radio. Rough calculation  shows that system
EIRP was in the neighborhood of 6.2 kW EIRP.

Good Luck and 73,
Scott AA5AM

On Sat, Sep 28, 2024 at 12:59 PM Ev Tupis via VHFcontesting <
vhfcontesting at contesting.com> wrote:

>  That's really interesting, Tor.  Looking at the claimed gain of M2
> antennas and how many elements they have, it looks like your 2x18 array sat
> around 20dbi of antenna gain.  100 w is 50 dBm.  Total ERP of 70 dBm.  That
> allows me to estimate what it will take (combination of antenna and amp) to
> work the "topmost tier" of 70cm EMEers via machine decode modes.
> Thank you!  That was the initial insight I was looking for as I strategize
> a bit.
> Ev, W2EV
>
>    On Saturday, September 28, 2024 at 10:44:37 AM EDT, RT Clay <
> rt_clay at bellsouth.net> wrote:
>
>  I'm not very experienced in EME, but in the 2022 and 2023 ARRL EME
> contests I set up a simple small (2x18 yagi) array for 432 (fixed
> polarization). I did have manual az/el pointing, but could not see the moon
> at rise/set. I only had 100w. Everything was set up outside so feedline
> loss was a minimum.
>
> In the 2023 contest I was able to copy 10 stations on 432 (part time
> operation). 8 yagi stations were pretty easy to hear- typically about -20
> to -23, but couldn't hear me. Only the biggest of the big guns (3 out of
> the 10) could hear my 100w.  So my advice is that you really will want more
> than 100w. I'm sure that rotatable polarization would help also.
>
> Tor N4OGW
>
>    On Saturday, September 28, 2024 at 05:23:25 AM CDT, Ev Tupis via
> VHFcontesting <vhfcontesting at contesting.com> wrote:
>
>  Hi Joel,Thanks for the tip and perspective.  I've reached out to Peter
> first.  Two questions to ask, if you don't mind...
>
> When you refer to a single-yagi station, what size (or gain) antenna do
> you think was in use on 2m and 70cm?
> Do you think that elevation control at play for them or were they home
> stations aiming at the horizon?
>
> I'm thinking what it would take to setup at a hamfest or a field day to
> demonstrate EME, and make it a plausable approach for observers who are not
> likely to go home and setup H-frames. :-)
>
> I'll take further questions direct after this to avoid flooding the list
> with non-contest stuff.
>
> I sure appreciate your insights.
> Ev
>
>
>    On Friday, September 27, 2024 at 08:28:57 AM EDT, w5znjoel at gmail.com <
> w5znjoel at gmail.com> wrote:
>
>  Hello Ev,
>
> I operate EME on all of those bands (current and "back in the day) plus
> 222 MHz. Of course, the best person to get feedback from for the type of
> operating you're inquiring about would be Peter, KA6U. Also Gene KB7Q.
>
> 144 MHz will have the most activity, followed by 432 then 50 MHz. With a
> small portable station you will have to use the digi modes. The 2-meter
> folks still hang on to JT65B, the 50 and 432 gang use Q65.
>
> When Farraday rotation is not in play I can work a single yagi station
> with 100 watts on 144 and 432. 6-meters is more difficult as you will need
> some power with a single yagi.
>
> Chat with Peter or Gene, they can tell you more than you probably want to
> know about portable EME operating !!!!!
>
> 73 Joel W5ZN
>
> 50 MHz - 4x7 LFA 1.5KW
> 144 MHz 4x17 1.5 KW
> 222 MHz 4xFO15 1.5 KW
> 432 MHz 8xFO25 1.5 KW
>
>
> -----Original Message-----
> From: VHFcontesting <vhfcontesting-bounces+w5znjoel=
> gmail.com at contesting.com> On Behalf Of Ev Tupis via VHFcontesting
> Sent: Friday, September 27, 2024 6:47 AM
> To: VHF Contesting eMail Remailer <vhfcontesting at contesting.com>
> Subject: [VHFcontesting] 6m, 2m, 70cm EME
>
> Of the 6, 2, and 70cm bands (those that are most likely to be in a modern
> HF+ radio), which band has been shown to support EME with the least overall
> ERP?  I'm thinking "portable EME" where it isn't possible to transport big
> antennas or a generator to have a kw amp. :-)
>
> Assume that this portable station would target QSOing with only the "top
> tier" of well equipped DX stations.
>
> I'd be interested in only recent experience rather than "back in the day".
> Also interested in both CW (human decode) and FTx (machine decode) modes.
> How little power and antenna (ERP) has been successful in making EME
> contact(s) and on what band/mode?
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