From: Frank Sent: Saturday, July 13, 2019 6:55 AM To: Pete Juliano Subject: Re: 40M QSO with N6QW
GM Pete
Yes fun QSO last night. You did have a great signal and excellent audio from your HB SDR .
Lots of great info on your website.
I am enjoying my wire beams. I have two five element wire beams mounted end to end beaming Europe that I get on that direction a lot. I'm planning to get an Array Solutions StackMatch soon that will help my signal even more.
Keep up the good work with the SDR rigs Pete.
I look forward to our next QSO.
73
Frank WA3RSL
On Jul 13, 2019 9:42 AM, "Pete Juliano" wrote:
Hi Frank,
Last night was the first coast to coast QSO with my homebrew SDR Transceiver. Thanks for the signal report and the comments on the signal.
This has been a fun project and my main band of operation these days is 40M. I have the capability to put the SDR on 75 as well as 20M. The second prototype (now in work) will use plug in coils for those two bands. It is simply amazing what can be done with a $35 computer.
I have several websites but one has been dedicated to SDR and there is more documentation about the SDR project.
According to report by Xinhua, a microsatellite developed by the Harbin Institute of Technology in northeast China's Heilongjiang Province, which is now orbiting the moon, captured mesmerizing photos of Earth during the solar eclipse in the early hours of Wednesday (Beijing time).
It is to be noted that the microsatellite, weighing 47 kg and named Longjiang-2, was sent into space on May 21 last year, along with the Chang'e-4 lunar probe's relay satellite dubbed as "Queqiao" and entered lunar orbit four days later.
According to the research team from the Harbin Institute of Technology, the microsatellite carries a mini CMOS camera that only weighs 20 grams, which makes it easy to operate, and it can take pictures at short intervals.
“Since the camera uses an automatic exposure mode, the camera's field of vision must contain a certain area of the moon to realize correct exposure. When the recent total solar eclipse occurred, the orbiter was flying over the far side of the moon. In the few minutes before and after the moon blocked the earth, all the conditions were right to take the pictures,” Xinhua further quoted the team as saying.
According to the team, to avoid becoming space rubbish, the microsatellite will be controlled to crash into the moon after it stops operation at the end of July.
As per Xinhua, the team cooperated with amateur radio operators in Spain and Germany in taking and receiving the photos. Nearly two pictures taken by the microsatellite during the solar eclipse were sent back to Earth on Wednesday.
I don't know why, but this weekend I got the urge to get on the air with a very low power homebrew QRP rig. I reached for my Tuna Tin 2 -- Herring Aid 5 combo. I call it the Fish Soup 7 (seven transistors in total). I first tried to turn this rig into a transceiver by taking the VFO signal from the receiver (it is direct conversion) and using it to excite the Tuna Tin 2, but it just didn't work out. The oscillator in the Herring Air 5 is very bare bones -- no buffering and an LC circuit that is mostly L (10 uH). It became very difficult to get a stable amount of CW offset. So I went back to crystal control for the transmitter. I did replace the 5K tuning pot in the RX with a 10k 10 turn pot (thanks to W8NSA). Tuning is now very smooth. I used my old UK freq counter to monitor my receive freq. (Thanks to Tony Fishpool G4WIF-- back in 2009 he sent me the CMOS chip that brought this counter back to life.) I was putting out about 750 milliwatts. I had a very quick contest-like contact with K2D -- one of the "13 Colony" stations. Then a longer chat with Hank K1PUG (see video above). I had lost my 7050 crystal, but this morning it re-appeared. TRGHS. As you can see in the video I am using the beautiful VU3XVR key that Farhan brought me from India. This was fun. I may try to put a VFO of some sort into the TT2, just to get more agility. But I want to keep things simple. Look for me on 7050.
The creators of "Plasma" and "Blueprint" YouTube channels have collaborated on this very interesting video about spark-gap radio transmitters and receivers. Really nice work. Especially impressive was the coherer build by Blueprint. I detect the spirit of Nikola Tesla in his lab!
Once deployed, LightSail 2 will automatically transmit a beacon packet every few seconds, which can be decoded into 238 lines of text telemetry describing the spacecraft's health and status, including everything from battery status to solar sail deployment motor state. Every 45 seconds, the spacecraft will transmit "LS2" on the spacecraft's frequency of 437.025 MHz, within the Amateur Radio 70-centimeter band.
In a series of e-mails to the BITX20.io group, Ashhar Farhan VU2ESE provided background information on the origins of his new "RF Lab in a Box' -- the Antuino. He also explained how the device performs the SWR meter, Power Meter and Scalar Network Analyzer functions. Farhan's Antuino Page: http://www.hfsignals.com/index.php/antuino/ Dec 27, 2018 to BITX.io peeps,
while trying to measure the swr on the cubesats, i figured i couldnt use any of the analyzers i had access to. they were simply too big to be stuffed inside a 10 cm cube. my simple resistive bridge was too insensitive for any reasonable work. so, i sat down and made an antenna analyzer from a spare raduino.
the code is wobbly and just about enough to get my work done. it works on a superhet principle. this is not my clever idea, rahul had mentioned this approach taken by a russian builder. i havent seen the original design. it would be interesting if rahul or someone can point me in the right direction.
first, thanks. there is substantially your code in there.
second, onto the circuit. it uses two clocks. not three. the third is a spare output. more on that later.
the circuit here uses a resistive return loss bridge. the clock 1 drives the bridge through the R22 to a low level of -10dbm. If the bridge is perfectly balanced (that is, the antenna, R21, R29, R16, all the four are the same ohms), then, there will be no RF developed across pins 3 and 4 of the ADE mixer. Under ideal match conditions, there is no RF across the R26. As the mismatch increases, so does the RF across R26.
We could directly detect the voltage across the R26 with a diode detector. This is quite a popular configuration with most of the simple resistive kind of SWR bridges (like the one designed by Dan Tayloe). This simplicity comes at a cost. The problem is that the detector responds to all the RF between the arms. For instance, if another ham down the block starts to transmit, that energy will show up across the R26 and you will get crazy SWR. I had that problem with broadcast FM showing up on my 7 MHz dipole! Even if there was no RFI from elsewhere, harmonics and spurs from your own transmission can show false readings.
Here is an example: a 7 MHz transmitter with a 14 Mhz harmonic that is 20 db down is connected to a 7 MHz dipole. The dipole is perfectly tuned to show 1:1 SWR, hence, it should show no RF across R26. However, as the antenna is reflecting back the 14 MHz energy, the 14 MHz shows up across the R26.
What's the solution to get a clean dip?The solution is to substitute a simple detector like a diode detector with a simple receiver that is tuned exactly to the frequency that you want to measure the antenna at.
So, the ADE-1 mixer, Q2, Q1 together form a very simple superhet receiver with 25 MHz IF andCLK2 as the local oscillator. The RF at the IF is directly detected and converted to db range with the AD8307. This simple configuration makes this a very powerful instrument.
Here are things you can do with it:
1. Switch off the CLK1, now you have a receiver that can very accurately measure RF levels at any specific frequency in db range. For instance, you connected your transmitter with a suitable RF attenuator to P3, you can tune to various harmonics and measure them very accurately. If you inject a two tone signal into an amplifier, you could easily measure the IMD and IIP3.
2. With the CLK1 on, the instrument now measures the return loss. you can measure the SWR of an antenna, S11 parameters of an amplifier, filter, etc.
3. With CLK1 off, CLK 2 on, the CLK2 can now tune to the frequency tuned in by the receiver's LO (CLK0). By connecting a device/filter between P3 and P4, you can sweep it to measure the gain, frequency reponse.
4. As the diode mixer (ADE-1) has harmonic response, a local oscillator at 135 MHz, will also convert a 430 MHz signal into 25 MHz IF (430 - (135 x 3)). This is possible because we are driving the diode mixer with a square wave from the Si5351 and the local oscillator at 135 MHz also has a 405 Mhz harmonic in it. Hence, the range of this instrument extends to UHF.
The ADE-1 mixer is quite similar to the ubitx mixers. You could even use ubitx kind of discrete version of a diode mixer, it doesn't work too well beyond 50 MHz. The pins 4 and 3 of the ADE-1 are the primary winding of the RF-input side transformer. The documentation recommends that we must ground 4, but that is not essential. We need a differential drive between those two pins, that is what the bridge provides anyway.
73, f
jerry,
i built it so i could stuff it inside the cubesat to measure the antenna. an external spectrum analyzer and its cables were upsetting the RF model hence, i needed something that could read the return loss sitting inside the cubesat. then, i borrowed by daughter's DSLR with a monsterous tele lens and sat 100 meters away to read the the LCD display as it swept through the range.
the analyzer was removed once we knew the correct dimensions and the actual payload went inside the bird.
So far I have made about two dozen contacts with the new RADIG. Just finished one with a ham I know in New Mexico and he is an RF Engineer –he was a designer at Alpha. I asked that he do a critical review of how I sounded and looked on his SDR – a good report and his comment was that if I hadn’t told him he would have guessed it was a $4 or $5K box.
So another goal achieved –on my 60th year anniversary and this makes #37.
Sideband Engineers Models 33 and 34 -- Thanks Pete! Hans's QSX SDR Rig at Dayton-Xenia and FDIM W8SX FDIM interviews Pete's SDR Projects -- Update The Peregrino SSB transceiver in the summer SPRAT Why no rare earth cell phone speakers in ham projects? My HDR "waterfall" project Farhan's Antuino Cubesat origins RF Lab in an box SWR, PWR, SNA Superhet receiver with ADE-1 at front, and log IC at the output Adapters (SMA to BNC) help DON'T BLOW UP THE INPUT RESISTORS (LIKE I DID!) My dirty DIGITIA -- Denial, then acceptance FFT Useful programs: SPURTUNE and ELSIE A better bandpass filter for the DIGITIA The importance of a good test set up with Antuino Manassas Hamfest: WA1UQO, W4WIN, AI4OT MAILBAG: KG7SSB WA3EIB VK4PG W3BBO Jeff Tucker -- Who owns Drake 2-B #4215? KN4BXI KC5RT K3ASW
