[50mhz] Re: 6m EME

[LANCE COLLISTER]

Hello Jan,

It is great to hear from you!  I see from watching the ON4KST 6m chat page that 
you have been quite active on 6m EME recently ;-)  And since you got that ACOM 
1000, you have a great signal!  Congratulations especially on your FB 'single yagi 
to single yagi' contact with ZL3NW!

The QTH at your club station overlooking the water is certainly a perfect QTH for 
lots of ground gain on your moonrise with your single yagi!  I am looking forward 
to a contact with you in that direction myself to see how much louder you are than 
when we first worked during your moonset.  Keep up the great work!

Jan Egholm wrote:
> Hi Lance,
>  
> TNX for your reply.
>  
> I am planing to improve my setup for 6m EME, as I find this very 
> exciting :-)
> But wood realy like to se more stations active.

Yes, I still find it very exciting to contact stations off the moon on 
6m...especially during times like this when the band is otherwise dead.  The fact 
that we are at the bottom of the sunspot cycle means this is the BEST time for 6m 
EME because the signals can travel out to the moon and back without any 
interference from an active geomagnetic field.
>  
> I found out that I will get about 2db by changing the coaxial cable, so 
> this is one of the fyrst thing I will improve.

Yes, that sounds like an easy and logical place to start since it will help you on 
both receive and transmit. You should notice a 4 dB increase in the strength of 
your own echoes ;-)

A good "rule of thumb" is that if you can keep your feedline loss under one dB, 
you won't be losing anything by not having a receive preamplifier out at the 
antenna.  Many 6m EME operators have preamps in the shack, and just use low loss 
feedline to the antenna for both receive and transmit.
>  
> Then I have been thinking on improving the antenna.
> And allso try to get more time on the moon.
> Fyrst I am not sure if I maybe shall stack two 6el side by side or 
> getting a singel yagi with more elementh's
> Allso I am thinking of adding elevation on the antenna, but know that I 
> will loose the ground gain, but estimate it's possible to work the 
> bigger stations on elevation.

Yes, it is a big step changing from a single yagi aimed on the horizon, since you 
will be giving up lots of ground gain (possibly 6 dB) as soon as you start to 
elevate the antenna.  That extra ground gain is what makes many 6m stations 
capable of EME with their yagis.

I usually figure that it is necessary to have about 14 dBD antenna gain to have a 
station that will enable you to work other similarly sized stations.  That is 
typical of what most single yagi stations have with their ground gain when they 
are aiming on the horizon, or what a really big yagi (such as my M2 6M11JKV) has 
when it is elevated.  I can hear my echoes about half the time with that amount of 
antenna gain.  You can also come up with that same amount of gain with a pair of 
6M7JHV 7 element 31' long boom yagis aimed up in the sky, or four of the computer 
optimized 4 element yagis like the one used by OZ1BNN:

http://oz1djj.geronne.dk/oz1bnn.htm

>  
> It wood be very nice if you can comment on this, specially on 2x6el side 
> by side or larger singel yagi.

It is difficult to easily elevate a single big yagi (mechanically, I can only 
elevate mine up to 45 degrees), so I would suggest that you consider either 
stacking a pair of 7 or 8 element yagis side by side or putting up four smaller 
yagis on an 'H frame'.

If you stack the long boom yagis side by side, you should have them vertically 
polarized to avoid interaction with the horizontal cross boom and phasing lines. 
And of course, you should use insulated cables such as Phillystran (1/8" diameter) 
  for supporting the booms to avoid interfering with the vertical elements:

http://www.phillystran.com/

If you stack such antennas side by side and vertically polarized, it is 
mechanically quite simple to elevate them and they can be mounted very easily at 
the top of the tower without any extra mast sticking up.  However, most people 
agree that you will lose about 3 dB ground gain compared to a similarly sized 
horizontally polarized array.  So, a pair of vertically polarized yagis should be 
about the same ground gain as a single good horizontally polarized yagi aimed on 
the horizon.  Of course, you would then also be able to elevate the pair of yagis 
and would enjoy the ability to have 3 dB more gain than a single yagi when you are 
aiming up in the sky to track the moon.  And, the vertically polarized antennas 
should work very well for you on Es and F2.  The possible compromise is that they 
sometimes seem noisier on receive than horizontally polarized yagis.

The other option is to build a small H frame and mount four computer-optimized 4 
element yagis horizontally polarized.  Such an array also can be easily balanced 
and mounted right at the top of the tower.  It also can be elevated easily. 
HL4GHT has built such an array for 6m with full elevation:

http://www.bigskyspaces.com/w7gj/HL4GHT.jpg

>  
> Vy 73's
> Jan OY3JE
> 
> PS. I have put my EME log on my homepage
> http://www.oy3je.egholm.fo/OY3JE_6m_EME_Log.html so I am very pleased to be up
> to 19 initials by so short time as it dont looks like there are so many active
> for the time.
> 

Yes, you are sure doing GREAT on 6m EME!  I am not sure why there are not more 6m 
stations on EME right now to take advantage of this best time during the solar 
cycle.  Interface units to enable digital modes such as PSK31 and RTTY (for HF) 
and JT65A and JT6M (for 6m weak signal work) are very readily available, and new 
rigs such as the Elecraft K3 even have such computer interfaces built-in.

It must be that most people simply are not aware that their single yagi stations 
are capable of working anywhere in the world right now, using the moon as a 
reflector.  I know there are more and more people getting on 6m EME all the time 
now, and I am sure that you will have more stations to work with whatever kind of 
new antenna you decide to build ;-)  I am personally on a 'schedule' of working 
about one new DXCC every month now using EME on 6m.

Good luck and VY 73, Lance
-- 
Lance Collister, W7GJ (ex: WN3GPL, WA3GPL, WA1JXN, WA1JXN/C6A, ZF2OC/ZF8)
P.O. Box 73
Frenchtown, MT  59834  USA
QTH: DN27UB
TEL: (406) 626-5728   URL: http://www.bigskyspaces.com/w7gj
2m DXCC #11, 6m DXCC #815