61
The RF Workbench / Re: Corsair transmitter and 6KHz limiter PCB made up
« on: August 24, 2021, 1317 UTC »
Crickets.....................................
Shortwave Pirate Radio In North America And Around The World, And Other Signals That Go Bump In The Night
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Hi Ed
Any further updates on these experiments? I'd enjoy some mobile hifer experiments. I'm going to see how the little rig works hooked to a hustler mobile in the car, but I'd like to try for some mobile Hifer QRSS receptions too.
Also...about those "hidden" two button options.........................................?
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62
HF Beacons / Re: HF Beacon Frequencies
« on: August 21, 2021, 1351 UTC »
I'd guess that originally they spring up where they are because of the availability of cheap crystals :-)
63
Part 15 AM and FM Station Operation / Re: This Knight lit up a lot of potential broadcasters!
« on: August 21, 2021, 1240 UTC »
Lit up is a good term, with that transformerless design!
64
The RF Workbench / Beacon Keyer hardware
« on: August 20, 2021, 1807 UTC »
I've been playing with a Tiny85 as a beacon controller, due to its efficiencies
I lowered the clock speed to 1Mhz from 8. Nothing about a keyer needs 8Mhz clock.
I built an external high side switch circuit (2n3904 / 3906 pair) keyed from a digital output from the tiny to turn the 12v to the transmitter OFF when it's not actually sending something. There's no use burning up power in the bias circuit if it's idle.
Transmitter runs off 12V, of course the Tiny needs 5. A 2950 regulator is fine for supplying the 5V.
I put the Tiny into SLEEP mode (there's some libraries out there on the web to do this. Not so many for the Tiny, but there are some) when it's not doing anything useful (between transmissions, etc). This keeps the Tiny running but shuts down most other functionality (inputs/outputs/DAQ's etc) to save power. The transmitter is a Pixie (with no RX circuitry) and output is about 550 mW into 50 ohms. I'm pretty sure I can do better than this by replacing the lossy molded inductors in the LP filter with small toroid versions.
Anyway, here's some supply current numbers with the results. These numbers include the current to the ATTiny and the transmitter
Vcc 12.5
Icc (Transmitting) = 92 mA
Icc (Transmitter biased but not being keyed) 16mA
Icc (Transmitter disconnected , Tiny in sleep mode) 0.45 mA
That last number (0.45 mA for the whole system in sleep mode) is a nice one if battery capacity is of value to you.
If I recall correctly, the Arduino Nano pulls about 24 mA doing nothing, which is why I spent the time looking at the Attiny. This is just a hint of a way to go that might help if you're looking to run off a battery.
Syfr
I lowered the clock speed to 1Mhz from 8. Nothing about a keyer needs 8Mhz clock.
I built an external high side switch circuit (2n3904 / 3906 pair) keyed from a digital output from the tiny to turn the 12v to the transmitter OFF when it's not actually sending something. There's no use burning up power in the bias circuit if it's idle.
Transmitter runs off 12V, of course the Tiny needs 5. A 2950 regulator is fine for supplying the 5V.
I put the Tiny into SLEEP mode (there's some libraries out there on the web to do this. Not so many for the Tiny, but there are some) when it's not doing anything useful (between transmissions, etc). This keeps the Tiny running but shuts down most other functionality (inputs/outputs/DAQ's etc) to save power. The transmitter is a Pixie (with no RX circuitry) and output is about 550 mW into 50 ohms. I'm pretty sure I can do better than this by replacing the lossy molded inductors in the LP filter with small toroid versions.
Anyway, here's some supply current numbers with the results. These numbers include the current to the ATTiny and the transmitter
Vcc 12.5
Icc (Transmitting) = 92 mA
Icc (Transmitter biased but not being keyed) 16mA
Icc (Transmitter disconnected , Tiny in sleep mode) 0.45 mA
That last number (0.45 mA for the whole system in sleep mode) is a nice one if battery capacity is of value to you.
If I recall correctly, the Arduino Nano pulls about 24 mA doing nothing, which is why I spent the time looking at the Attiny. This is just a hint of a way to go that might help if you're looking to run off a battery.
Syfr
65
HF Beacons / Re: The Desert Whooper
« on: August 20, 2021, 0007 UTC »
Great posting, and I'm really glad to hear that DW is back to making serious RF! Very strong on the usual Kiwis tonight
66
22 Meter Band HiFER Beacons / Re: Beacon "RF" Back On The Air 13564.4 CW
« on: August 15, 2021, 1628 UTC »
Thanks! Will give it a listen
67
Equipment / Re: BELKA DX
« on: August 10, 2021, 2122 UTC »
Thanks Sig, for the info on the Belka and IQ output. That's a really nice looking grab. I'll have to give it a go also with some QRSS signals. I took the Belka mobile, and it hears the ignition noise in my truck pretty well! :-)
Hooked to a Hustler mobile whip I found that it would make a decent ham receiver for casual CW contacts on 40. There's really not enough audio to overcome background noise with the built in speaker but it works great with earbuds.
Will see how stable it is during some QRSS grabs
Hooked to a Hustler mobile whip I found that it would make a decent ham receiver for casual CW contacts on 40. There's really not enough audio to overcome background noise with the built in speaker but it works great with earbuds.
Will see how stable it is during some QRSS grabs
68
Equipment / Re: Construction of Shortwave beacon
« on: August 08, 2021, 1633 UTC »
A couple of suggestions! You do very very nice building, far better than I can do.
After some iterations of homebrewing, Ive found you can't beat the cost of the "Frog Sounds" QRP kits that the various chinese suppliers produce . You ccan modify the LPF on them and ditch the receiver section and end up with a half watt output transmitter, board and all parts (minus the crystal of your choice) for about $2.99 if you buy 10 at a time and shop carefully. Yes, the LPF is using inefficient chokes rather than toroids, etc but..... you can substitute if you wish.
As far as a micro goes, the Nano is what I started with too. Then I found the ATTiny85 which is way more power efficient and ...well...tiny. There's some libraries out there that sleep it at under a mA. There's still enough pins left over to say...(hypothetically) turn the DC bias OFF to the transmitter (no use powering that voltage divider if the transmitter is off) take battery measurements, and convert to a morse string, etc etc. and have space left over for other fun things (like high side and low side switches).
I've experimented with the charge controllers that are available (also Pride of China) and they work well. I still use a LDO 5V regulator (to-92) for the regulation from the battery to the Tiny, but they're pretty efficient. When the Tiny is in sleep mode, there's not much load to warm up even that tiny regulator. I use the full battery voltage to the transmitter. Jim's suggestion on those little battery charge boards is a good one.
Hope those help!
After some iterations of homebrewing, Ive found you can't beat the cost of the "Frog Sounds" QRP kits that the various chinese suppliers produce . You ccan modify the LPF on them and ditch the receiver section and end up with a half watt output transmitter, board and all parts (minus the crystal of your choice) for about $2.99 if you buy 10 at a time and shop carefully. Yes, the LPF is using inefficient chokes rather than toroids, etc but..... you can substitute if you wish.
As far as a micro goes, the Nano is what I started with too. Then I found the ATTiny85 which is way more power efficient and ...well...tiny. There's some libraries out there that sleep it at under a mA. There's still enough pins left over to say...(hypothetically) turn the DC bias OFF to the transmitter (no use powering that voltage divider if the transmitter is off) take battery measurements, and convert to a morse string, etc etc. and have space left over for other fun things (like high side and low side switches).
I've experimented with the charge controllers that are available (also Pride of China) and they work well. I still use a LDO 5V regulator (to-92) for the regulation from the battery to the Tiny, but they're pretty efficient. When the Tiny is in sleep mode, there's not much load to warm up even that tiny regulator. I use the full battery voltage to the transmitter. Jim's suggestion on those little battery charge boards is a good one.
Hope those help!
69
HF Beacons / Re: Windy 4102.85 malfunction?
« on: August 01, 2021, 2310 UTC »
That's a good point Jim. Peak voltages are in the 12.3-12.6 (a 3 cell Li series string?) range now, rather than close to 13 like you'd expect with lead acid at the end of the afternoon of full sun . It's been a long time (until very recently) since Windy was charged up to over 12.
To whomever responsible: Thank you!
To whomever responsible: Thank you!
70
HF Beacons / Re: New whooper beacon on 4095.65
« on: August 01, 2021, 2239 UTC »
It's back at full speed now.
Both it and Windy are reporting a temp of 104 which is interesting. Internal temp is 109.
Both it and Windy are reporting a temp of 104 which is interesting. Internal temp is 109.
71
HF Beacons / Re: Windy 4102.85 malfunction?
« on: July 30, 2021, 0026 UTC »
A battery voltage of 12.6 on Windy is good and surprising news!
When I was listening last week, I never heard it above 11.9.
Could it be that it was serviced?!
When I was listening last week, I never heard it above 11.9.
Could it be that it was serviced?!
72
HF Beacons / Re: "D" 13820 kHz CW 2156Z 7/29/21
« on: July 30, 2021, 0024 UTC »
Now that's interesting. Was it tone modulated SSB being toggled betwen USB and LSB
73
Equipment / Re: BELKA DX
« on: July 29, 2021, 1253 UTC »Great - thank you.
I may have to borrow the other laptop for this - the cheap laptop at the radio desk is running from a plug-in USB sound I/O that I now realise only has mono input.
Further, I'd like to explore going really mobile with Belka and a spectrum analyser to check out HiFERs from other locations. A brief test with the laptop and the Belka receiving with the whip resulted in 5&9 reports to the computer, traced to the screen. Second test was to try a small tuned loop. Care with the feed decoupled most of the QRM from the PC. I think this had promise, but for the test, conditions were just awful.
Ed
Hi Ed
Any further updates on these experiments? I'd enjoy some mobile hifer experiments. I'm going to see how the little rig works hooked to a hustler mobile in the car, but I'd like to try for some mobile Hifer QRSS receptions too.
Also...about those "hidden" two button options.........................................?
74
HF Beacons / Re: New whooper beacon on 4095.65
« on: July 25, 2021, 1519 UTC »
No joy this morning, although Windy is Q5 this morning (and only a balmy 92)
75
HF Beacons / Re: 4096.34 New Dasher?
« on: July 25, 2021, 0256 UTC »
I'm really disappointed I didnt get to hear the DW live and in person here on the left coast.
Windy always anchors the band though. A cool 94 a few min ago .
Windy always anchors the band though. A cool 94 a few min ago .
