Hi Dave. Thanks for the tip on the cavity filter. I hadn't considered that.
With the assumption that KB7Q was pointing at the horizon, I calculate out...
9wl antenna at +20 dBi450 watts = 56 dBmPolarization "anomoly) = -3dB (equal V
and H signal strength for you)
Ground Gain +3dB
Total approximate system ERP (coax loss unknown) for the QRP side = ~78 dBm
This is quite an education for me. Thanks, Dave!
Ev, W2EV
On Sunday, September 29, 2024 at 07:26:32 PM EDT, David Olean
<k1whs@metrocast.net> wrote:
Hello Ev
I have been playing on 432 and 222 MHz of late. It seems that a power
level of 100 watts will allow you some limited success on 432, but only
with the most well equipped stations. I would strongly suggest rapid
polarity adjustments. That is easy with a single long yagi. The other
suggestion would be to have a very good and selective front end. A big
copper cavity in front of your preamp is probably needed if you are
going to travel to different spots. I can almost guarantee that strong
digtal TV stations on the low end of the UHF TV band will kill most
preamps. I have had serious trouble both on 222 and 432 that really
compromised my hearing ability. After the re packing of the UHF TV
channels, there is probably a multi megawatt TV station nearby that will
kill your 432 front end. The end result is that digital noise gets into
the preamp and s/n ratios go South!
I tried today with KB7Q who was portable in Hawaii. I have a mid level
station and had a bunch of trouble due to poor EME conditions. I used 4
X 12 el with polarity rotation. Gene had a single long yagi (9wl) and
450 watts. Polarization was quite diffused much of the time, with V and
H not being much different. It made Gene's signal very difficult to hear
even with his 450 watts. I am sure a better day would have been easier,
but you have to realize that many days will be less than optimum.
I think 432 is your best bet with low power. I have tried 100 watt QSOs
on 222, but success is fleeting. I have done it with my four big yagis,
but it is barely possible. I am sure that 144 is even worse unless you
are talking about 2 or 3 "super stations". Good luck.
Dave K1WHS
On 9/27/2024 7:47 AM, Ev Tupis via VHFcontesting wrote:
> 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?
> _______________________________________________
> VHFcontesting mailing list
> VHFcontesting@contesting.com
> http://lists.contesting.com/mailman/listinfo/vhfcontesting
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