Ham shack satellite communications

Maybe ask persons who use AmSat (an amateur-satellite initiative).

(S.

Joseph A. DiVerdi [1] hosted a last minute, surprise forum at our Division's Ham Convention [2] last August. He brought along a 3U satellite to show off at his vendor's table. Instead of thrusters, it spins a miniature momentum wheel. A de rigueur RTL-SDR and Raspberry Pi sat next to the satellite on his table. Long story short, an EB144RK2M eggbeater will be used, along with a cheap LNA module from ebay [3]. It ought to be easy enough to replace the original LNA chip, if anyone knows of a superior LNA chip.

Note.

Danke,

Nice board, did you test it?

Good idea. It will be tested upon delivery.

Danke,

What led you to choosing RTL-SDR for the "muscle"? Presumably, you're only interested in receiving (?).

What sorts of broadcasts?

Am 14.09.26 um 17:14 schrieb Don:

For 432 it is this one <

Why? because I made it to fit my likings.

Selectivity: <

DL7APV (RIP) measured 0.25 dB noise figure, my own 8970B said 0.5 dB. The difference could have to do with the bandwidth of the SAW filter on 432 MHz vs. the bandwidth of the noise meter, and my 346C noise head

• Rosenberger attenuator hasn't seen a cal lab for a long time.

You might be interested in these email reflectors:

Am 16.09.26 um 15:37 schrieb Gerhard Hoffmann:

Oooohps, twice same pic. Selectivity is the pic to the left.>

I have this for 2.4 GHz:

A lot more stuff, not really active on ham RF atm.

What also makes a very good receive antanna are the old TV antenna racks:

Your custom LNA is perfect! It inspires me to make my own LNA, after my nascent satellite station becomes fully functional for both transmission and reception. For the time being my strategy is to minimize my learning curve. It's supposedly possible to run DC over coax to the LNA. But again, to minimize my learning curve, a separate outdoor DC cable will be used instead. Thank you for sharing the email reflectors. A Deep Space Exploration Society

Danke,

Am 16.09.26 um 16:25 schrieb Jan Panteltje:

Do you have any info on that Spectrian stuff?

Methinks I have the same but can't find the info anymore.

I bought it on ebay, March 2019 says the time of this file. Time flies :-)

Below is what I have saved from the seller, the ebay link below no longer works, seller is still on ebay (google KI4NPV)?

From:

Picture Information

Details about 75W Spectrian Linear RF Amplifier Board 2.3-2.35 GHz 18dBg 24/26V

This is a 75W linear amplifier board as removed from a new Spectrian power amplifier which is optimized for 2.30-2.35GHz but is also useful up to 2.45GHz at reduced power an gain. This amplifier board does not require any tuning for use on the ham band! Required supply voltage is 24-26Vdc at about 17A. Input drive required for 75W output power is 1.25W. Power gain is 18dB. Saturated power is 80W+. This is the final Rev. for this board design (Rev A)which has larger plated through holes and the holes have been sealed so the silicon grease does not come through the top side when bolting the board down to the heat-sink. The earlier rev. were all number revs with open vias. I sell the older "number rev boards" at a lower price on other auctions. The sweep photo shows one of these amps putting out 80W with about one watt input at 2304GHz. The output (CH1) reference is set for 100W (50dBm)with a scale factor of 5dBm/division. Channel 2 is the input power with it's reference set for 10W (40dBm)with 5dBm/division. Sweep is from 2.2-2.6GHz with 50MHz/ division. Looking at the output plot you will see the level 1dB down from 50dBm or 80 Watts and the input 9.4dBm down 40 = 30.6dBm, slightly over one watt. Looking at 2450 MHz you can see the output is down 4dB form 50 - 46dBm = 40W. Note the preamp I am driving this PA with is not linear with frequency over this full range as indicated by channel 2. Circuit board is on an integral .062" solid copper heat spreader. Both the board upper surface and the heat spreader surface are heavy gold plated. Board needs to be mounted on heat-sink using Silicon grease and 7ea.

Florida buyers must add 7% (or actual amount for your county) sales tax or mail me a signed photocopy of your Florida Resale Certificate with your payment! I do combine auction winnings when ever possible to save buyers money. I do ask that buyers help keep track of any auction shipments they want to combine and email me for a total when they are ready. Fixed Priority S&H quoted prices are for 50 USA states. International Bidders pay actual S&H. Good luck bidding! KI4NPV [phone removed by eBay]

Power consumption 17 x 25 = 425 W heat 425 - 75 = (17 * 25) - 75 = 350 W Junction temp is 100? C ? Rth = 100 / 350 = .285714 C/w

That leads to this for heatsink:

Met een bijzonder effectieve warmteafvoer door de geoptimaliseerde holle ribben. Translated from Dutch: Very effective heat transfer because of hollow ribs. Garantee: minimaal 2 jaar Make: Fischer Elektronik

--------------------------

Thanks! :-)

I'm moving to a smaller qth for retirement and my house... well, entropy never sleeps.

Cheers, Gerhard

Am 16.09.26 um 20:31 schrieb john larkin:

Back when we were students at the Technical Univ Berlin we founded there the ham radio club DK0TU and had a club station that was good enough for earth-moon-earth on 144 MHz. It was fun to hear one's own echoes from the moon after 2.5 seconds.

Bernd, DL7APV was the biggest activist. His antenna can be seen here <

He's the one who measured my pre-amp.

Unfortunately, hie died shortly after retirement. We miss him.

@Don: You can get the Altium files if you want.

Gerhard, DK4XP

Thank you! Please forward your files and/or links to me at snipped-for-privacy@qsl.net

During its forum the Deep Space Exploration Society presented a brief video showing someone's granddaughter speaking into a microphone and hearing her own voice a few seconds later after an EME bounce. The antenna at the facility is a rock sold beast built in the 1960s, IIRC:

Danke,

That pic is from 1946, and they used tubes and point-contact diode mixers. Mediocre noise figures. I guess the moon is actually a pretty big reflector.

Being spherical, it must scatter the reflection over half the universe.

Am 16.09.26 um 22:18 schrieb john larkin:

Path loss is abt. 235 dB IIRC, give or take some minor deviations for exact frequency and current moon position in the elliptical orbit.

Impressive!