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Re: Expected noise results with Drake converter (no satellite.)



Barrie,

Just a note of thanks for the words of encouragement.  No I have not given
up trying to see what can be accomplished with the 18 inch DSS dish.  I do
think it is probably a little marginal and will require the best NF preamp
one can afford to work at all.

But after I fool with it enough to determine its potential, I will be
moving up to a 33 inch offset feed dish [actually it measures 34 x 36
inches]  this should provide about 5-7 dB more gain.  I am still using the
4-foot Andrews just temporary until my preamp arrives to give me some
margin in receive, but its location has a limited view at low elevation
angles [the satellite only rises to 30 degrees max up here] and I can
obtain an unobstructed view when >10 degrees.

Yesterday, I bought a replacement dish [39 inch, 1m] for my sat-TV system.
So I will steal the existing dish [33 inch, 84 cm] for use as my AO-40
dish.  It should be small enough to mount on the G-5400 az-el with my
M2-436CP42 and 23LY45 antennas for 432 and 1296 respectively.  The slightly
larger TV-dish will help on some marginally received TV channels ;-)

Since this is also an offset dish, there is no feed blockage of the dish
surface which can improve efficiency up to 60-70%  This would increase the
std gain of 24.5 dBic [50% effic.] to 25.7 dBic, theoretically.  With my
0.7 dBNF preamp this should give me pretty good receiving system for 2.4G.

I will pick up my "new" G-5400 from WL7BQM Saturday evening and work on
mounting everything Sunday.  I hope my preamp will arrive by Tuesday, so I
should be fully operational by then for modes US and LS.  Of course they
will have changed ALAT and ALON to (0, 170) by then so squint will be
terrible again ;>||

>From: barrie@perth.igs.net
>Ed
>
>Don't give up on the DSS dish. I followed your advice and had mine working
>on this morning's pass. Copied the Beacon and I8CVS at MA 106  Range 59 K. I
>haven't got any numbers but it doesn't perform as well as the BBQ. However I
>think it would be usefull once I use a pre amp.  The dish I used was surplus
>from a  friend and  is sold here by Bell Express VU . It  looks like the
>original manufacturer or distributor is DISH.  I snapped open the plastic
>housing and removed the original LNB. Made a woodedn plug to replicate the
>lower half of the LNB and provide mechanical connection to the original
>support arm. I wound the helix using 1/8 in. o.d. copper tubing available
>from an auto supply store. By flattening the end it and drilling a hole it
>made a nice spade lug fit over the center conductor and close enough to the
>reflector for the matching element.  It is self supporting on the N
>connector mounted on a 3 in. circular reflector. Ended up with 5  1/2 turn
>helix. I was waiting to cut it at 5 but since it worked I left well enough
>alone.
>
>The helix fits nicely inside the plastic housing with the reflector sitting
>outside the rear of the housing. I will try to fine tune it on future
>passes. These 2 AM local antenna projects in the back yard are taxing.
>
>Oh yes! I did note I had to lower the elevation by a few degrees from what I
>thought was the same elevation I was using on the BBQ.
>
>
>Thanks for your advice  73 Barrie VE3BSB


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