[MAMS] 5.7 GHz rainscatter question

[Dr. Gerald N. Johnson]

Two stages to 1 watt is 40 dB, easy at low frequencies, probably 
impractical at 5.76, but possible in several stages even without 
filtering. Probably need 20 dB gain to get a good NF on receive too.

For roving with a bigger dish, like the DTN that I took to the 10 GHz 
range at CSVHF, I'm thinking of assembling a car top or truck top 
carrier platform with probably a couple layers of 3/4" plywood. The 
bottom layer square and the top layer round separated by a 
chair/shelf/lazy susan bearing. I picked one up at a Cedar Rapids 
Hardware Store on my way home from CSVHF for $10 that claims to handle 
1000 pounds. I'll mount the dish with probably a turnbuckle for 
elevation control, and carry a quick acting woodworking clamp and a 
spacer that just fits between the two plywood pieces. When I travel I'll 
turn the dish for minimum wind load and clamp it. When I get the 
direction set I'll clamp it. I figure with a 30 or 40" round that I'll 
have enough leverage for easy enough aiming at 10 GHz and 4 more dB gain 
than my 18" dish.

The international microwave handbook chart says 18" at 5761 has 26 dB 
gain, down 5 from 10368.

N0NAS, Doug Reed, in the twin cities is taking apart some 6 GHz 
microwave links and mentioning their parts on the NLRS reflector this 
week. There might be some parts that you could make good use of.

I solved all my 10 GHz rig assembly problems and have confirmed it as at 
least a couple watts RF to the feed and about 4 dB NF which I heard lots 
of stuff with last year. The new preamp is no longer functioning well 
unless it was driving the IF into compression when I measured.

73, Jerry, K0CQ

On 8/8/2012 5:49 PM, Danny Pease wrote:
> You are right Jerry, the mixer is followed by a filter, no amplifiers of any
> sort after the mixer output probably lucky to be -10 dBm. It will need a
> couple of stages to get up to 1 watt, probably 3 or 4 if I add more
> filtering. I am guessing the 18 inch offset feed dish I have at maybe 25 dB
> of gain, so even a 1 watt output still is pretty low ERP. I am still on the
> lookout for a free 2 to 3 foot dish, but one that size is a bit harder to
> hold up for portable use. I have a place nearby that has one of the farm
> data dishes in the front yard, I may eventually get that one, no one has
> lived in the house for a few years now, so I know it is not being used.
>
> Danny
>
>