CRIP EATIN BREAD posted:

Sniep posted:

this is the HT antenna that i use on my FT-60R

quote:

The bladeRF x115 comes with a larger 115KLE Cyclone IV FPGA that provides additional room for hardware accelerators and signal processing chains including FFTs, Turbo Decoders, transmit modulators/filters, and receive acquisition correlators for burst modems.

maniacdevnull posted:

holy poo poo the next pass us supposed to be within 100m

!

Jonny 290 posted:

hook a loving generator to an antenna and spin it such that it works at 17,200 hertz instead of your normal 50/60. Add a switch in line. Boom, an EMP-proof transmitter that requires more mechanical than electrical engineers to service

Jonny 290 posted:

put down the chocolate covered banana and step away from the european currency system

what's yer angle, whatcha thinkin

cause i mean we can glue parts together in many ways but only some of them will make sense.

Jonny 290 posted:

okay, gotcha.

alright, so i am going to state that i am not a professional RF engineer. i do not know all the tricks and only know a bit of the math

in general, frequency conversion is best done at low signal levels. yes what you are wanting to do is in the realm of a broadband power amplifier.

but before we begin, i want to yap about construction practices. As your frequency goes up, two things happen - physical dimensions start to becomes bigger fractions of a wavelength, and circuits become more sensitive to the trace inductance and capacitance provided by the construction materials and methods. So if you're building a 3.5 mhz amplifier for a little bitty CW transmitter you can just make it in a pie tin or altoids can or whatever the gently caress, manhattan/dead-bug it, who cares it'll work fine. But if you're building a 2 meter amp, you need to at least keep your leads short, don't run wires parallel, etc. gigahertz range amplifiers use the PCB themselves as capacitances, inductances and transmission lines. think of it as macro-scale chip fabrication techniques, manipulating the substrate and layers to create circuit elements.

long story short, an amp to cover say 300 -3800 MHz (bladeRF range) is going to need to be constructed on par with any other 3.8 GHz amplifier. careful, careful attention to detail is gonna be needed. The upside is that some very cool chips exist that can make this almost as easy as can be. we've mentioned them before, but Monolithic Microwave Integrated Circuits are what you're looking for here. Get out your 15 watt iron and the brightest LED lamp you can because this is surface mount territory. No devices with leads allowed.

Basically small all-in-one amplifiers on a chip, they are usually built to take 50 ohms input and output, can be regarded as pretty idiot-proof gain blocks and have a design that lends them to fairlystraightforward construction at microwave frequencies. One of their signature traits is that they usually take their DC power input as a bias on the amplifier output - this seems backwards and wrong, but if you consider the case of an MMIC preamp mounted at the antenna at the top of a long coax run (to help combat cable loss for receiving) it means that you can literally just shoot DC up the line with a little tee in the shack and be done with it. If you want to power it via a separate line, you just hang an RF choke off the output line and feed DC through the other end of that. That's what you'll be doing for your TX amp project.

Now, as far as I know, you're going to be able to get somewhere between 500 mW and 2 watts with the biggest common MMIC that you can get off ebay or whatever. But you only have +6 dbm power output, and you're trying to get to +27 to +33 dbm. getting a wide band single mmic with that much gain is going to be tough. it'd be much smarter to find a PCB kit for a two stage mmic amp (these are on ebay for like 10 bucks, add two chips and a couple SMD caps/inductors and you're done) or even the full chassis+pcb kit that comes with SMAs and everything. Then just pick two MMICs - both of them should have the frequency range you care about, the bigger one should be speced for high power output, and the first stage selected should make up however much gain you want.

say you find a device with +27 dBm max output (500 mw) and 16 db gain. you need to find another 6 dB gain to get to 27 dB, but what would be nicer is if you had, say, a stage with 10-12 dB gain. Then you could back the bladeRF down to 1 dBm output (one mW), lowering the heat on the radio itself and keeping things more stable. then you have one stage of mmic that takes your signal up to like 10, 20 mW, and that signal drives your final MMIC to crank out five hundred milliwatts of sperm-destroying, pizza-reheating microwave power


words words words. i hope this has helped more than confused. i believe for your project it would be an excellent direction to take, as long as you are comfortable with a little bit of basic surface mount soldering.

Jonny 290 posted:

hey nice! that sounds like a pretty nice setup. i'm down on cash right now so my sdr in a tree project is going to have to wait but i'm thinking:

-raspi
-2x dongle
-1x hfupconverter
-mini-whip for hf, my new little 420 mhz (yes i cut it for 420 mhz) discone design for vhf/uhf
-ghetto POE using an 18v laptop adapter up the line, buck converter at the raspi to drop it to 5v

i figure i can fit all of this in a rougly 2 foot chunk of 4" ID PVC with tons of room to spare. cap the top and put the discone on top of that, mini whip in the middle, electronics at the bottom. maybe shield the raspi and sticks, not 100% sure yet. thinking its a good idea tho

longview posted:

yeah just solder whatever, if you need a connector that's exposed I'd go with N since it's somewhat waterproof

comedy option: MCX

spankmeister posted:

use rtl_tcp

longview posted:

integrated I/Q demodulator chip (linear), ADC (linear), FPGA, unless you want to to be easy

spankmeister posted:

idgi becuase you say


and then you say you don't want to use ethernet?

PuTTY riot posted:

also what's up with CW on the county fire freq

Maritime Historical Radio Society posted:

Each year the Cornish Amateur Radio Club organizes International Marconi Day (IMD), an on-the-air event to celebrate the birthday of the Great Man, Guglielmo Marconi, born on 25th April 1874. The IMD event is not a contest: it is an opportunity for amateurs around the world to make point-to-point contact with historic Marconi sites using HF communications techniques similar to those used by Marconi, and to gain an attractive Award for achieving the requisite number of Marconi stations worked.

K6KPH, the amateur station of the Maritime Radio Historical Society, proudly participates in IMD as an Award Station since we transmit from the historic 1913 Marconi transmitting station in Bolinas, CA. But this year our participation will be different and special. This year both the transmit and receive sites will be at historic Marconi locations.

All the buildings of the original Marconi receive site in Marshall, CA remain intact. Many have been lovingly restored for use by the Marconi Conference Center including one of the two Marconi cottages used by the Station Manager and Chief Engineer.

Now comes Ms. Kathy Wippert, Marconi Conference Center manager, with a generous offer to let the MRHS set up our receive site in one of those Marconi cottages. We will install vintage receiving equipment and our house built remote control panels to allow us to key the transmitters in Bolinas. With both transmit and receive sites at historic Marconi locations we think we will be one of the most authentic Award Stations participating in IMD.

The public is invited to visit the receive site at the Marconi cottage. We will have exhibits set up and maybe even MRHS merchandise available for purchase. The location of the Marconi Conference Center is stunningly beautiful, worth a special drive in itself. Why not make a special day of it with a beautiful day on the coast and a visit to a historic radio site?

quote:

KSM will also be on the air, keyed at various times from the Bolinas transmitter site and from the Marshall receive site. Do you hold a commercial radiotelegraph license? Visit us to exercise the privileges of your license and have it endorsed for operation at KSM. We expect that SS RED OAK VICTORY/KYVM will be operational on MF so you might get the chance to work a ship on 500kc!