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mods to AIDC 3733 to get rid of image noise and the notch at 2400



I obtained 2 aidc3733 and tested one with the antenna element, since the N
connector
was not yet available from Bob Seydler, and here are my results:
Sweeper and antenna: hp87610 into a 3 inch wire, about 4 inches from
antenna.
Adjusted drive at 2500 mhz for 10dbm output, this is the point where it just
starts
To compress. Step each 5 mhz and plot results. Power meter gigatronics
both under pc control with labview, done at work after hours.

IF 40-430 MHz.
RF 2080-2710 band pass filter.
2395 mhz: -12.5db relative notch
Instead of a notch at 2400 we need the notch at 2150 to eliminate the image
noise
from the preamp and whatever comes in the antenna, because the LO is in the
passband.
The easiest thing for me to try is put an 8 mhz xtal in the LO and see if it
will lock at 2048 mhz.
If it does this puts the image noise out of the bandpass filter. Makes 2400
come out at 322 mhz
which is fine for me because the recievers are icom7100s.
A 2256 LO with a 8.8125 mhz crystal would put image noise (2256 -2080 = 176
mhz still in the 2m passband but a 432 crystal 2400-432=1968 is way below
where it may lock up. 7.6875 mhz.

I have 8 meg xtals so thats what I am going to try.
After I get the N connector I can put it on the big antenna, I may just
switch between that one and
my old one to retain the wide freq range of the old LNB (IF 950-1450 LO
3650).
May have to put an rf relay out there and stuff the additional converter out
there.

I am testing the aidc3733 to see how far the LO will move and still stay
locked up,
because even after the 2400mhz notch open stub is removed(unsolder the
wire), I dont
want the image noise in the passband and want to get 2.2-2.3 ghz for space
shuttle and other
commercial satellites like tdrss ranging beacons.

I connected a power meter to the converter output thru a dc block.
Sweeping it gives the following: Note the dropout right where we want it to
work 2401:
Siggen needed -8.5 dbm to get 10dbm out at 4 inches away.
freq dbmoutAnt1 dbmoutAnt2
1995000064 -10.113 -10.902
2020000000 -5.468 -5.815
2044999936 0.432 -0.173
2084999936 7.622 8.245
2120000000 8.595 8.421
2150000128 7.921 7.837
2195000064 7.329 6.518
2240000000 7.858 6.489
2255000064 -1.121 -2.65
2260000000 -7.914 -9.556
2264999936 -18.211 -19.265
2270000128 -19.886 -21.44
2300000000 -2.294 -3.293
2304999936 2.866 2.072
2310000128 6.064 5.27
2315000064 7.051 6.346
2335000064 6.534 5.781
2350000128 6.559 6.145
2375000064 4.845 4.639
2384999936 1.957 1.956
2395000064 -2.557 -2.569
2404999936 0.809 0.635
2415000064 4.863 4.923
2430000128 8.186 8.024
2440000000 9.383 9.143
2455000064 10.098 10.132
2484999936 10.066 10.219
2500000000 10.138 10.016
2560000000 5.981 8.242
2620000000 7.18 8.11
2695000064 5.505 4.839
2720000000 4.291 2.738
2750000128 -1.398 -3.891
2780000000 -7.779 -10.822
2840000000 -19.095 -20.589





----- Original Message -----
From: "Mark L. Hammond" <hammond@surrealnet.net>
To: "amSAT-BB" <AMSAT-BB@AMSAT.Org>
> http://camel.campbell.edu/~hammond/ham/3373_stub_cut.jpg
>
> Hope this is right since I already cut two of my units here ;-)
>
> On the first unit, I can see nearly 3 S-units improvement on 3' dish
> (outside) from my harmonics generator in the shack!  Wow...quite an
> improvement.  Not very "technical," but it's the only way I can test.

You still have the image noise there too.
The noise will go down if you can notch out  the 2150 freq assuming you
still have 2278 LO.

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