How to teach a Cricket to ...
speak QRSS/DFCW for weak signal DXing
With no mods Cricket 80a's XTAL oscillator works very well on 40m, 30m and 20m.
On 30m '80a' puts out a full solid one Watt with a 10V power supply and almost two Watts at 13.8V .....
Cavaet 1, a second FET 2N7000 in parallel with Q2 is required, a third has no advantage
Cavaet 2, L1 and C1 must be modified
Cavaet 3, I use QRP Labs seven element 30m LPF kit
Additional hardware for QRSS
One five Volt regulator
(tbd) One 2N7000 or equivalent such as BS 170 to key the orignal Cricket
Maybe a different XTAL or QRP Labs Progrock or equivalent
... BUT ... there is NO reason why CRICKET can not beacon QRSS on 3579 kHz or almost any band say 30m :>) a work in progress here.
One 08M2+ (an 8 pin DIP). This part is included in several low dollar PICAXE fun kits, kit then becomes re-program platform
PICAXE USB cable
ARGO will display weak signals such as QRSS and DFCW for visual decode >free download< http://www.weaksignals.com
PICAXE programmer >free dowmload <
And for whom the modes toll
Caution! Some modes are 100% duty cycle, the final amp will smoke and toast if SWR is too high. It is very easy and practical to parallel a second or third FET to Cricker's class E final :>)
Maybe Cricket's receive audio (with no mods, tbd?) along with ARGO will display visual decode or additional free software download for hign speed CW (not QRSS, but 5 WPM +).
With additional hardware, one DIP PLL 567, tone decoder, hard wired prior to the 08M2+, receive CW audio at 10 WPM or better can be decoded in 08M2's firmware for additional projects and/or display on PC's dumb terminal. Up and running on my RockMite.
NOTE Due to time restraints (the Annual New Year's QRSS Party)
I have only assembled and tested Cricket's transmitter on 30m.
Some observations from others...re jitter on visual decode...
"May indicate power supply isn't giving enough current for the transmitter."
"glue a 4-40 Nut to the crystal can. What happens is the can temperature changes the crystal frequency abruptly. The nut glued on the top of the can changes its temperature profile and it quits Jittering"
Inspiration and Credit:
1) RockMite by K1SWL … One outstanding QRP XCVR, mod friendly and almost bullet proof. TNX Dave
2) Rookey the AmQRP Altanticon Kit for QRP Forum, by N2APB es N2CX, TNX George es Joe
3) PICAXE-Based Timer, QST, April 2016 by KT4WX, TNX Darrell
4) The PICAXE BASIC (language) EDITOR, WOW!!! What a delight
5) Morse Audio Decoder by S Robinson from the original Morse Magic © by M R Burnette. A special big TNX to Stuart and Mickey ... at 75 I figured maybe not enough time to finish this project writing my own Morse decoder, I tried, oh how I tried and almost quit until google gave up your ‘secret’… my code was only lQQking at half the data available... !big-BIG TNX! for your Morse Audio Decoder
6) Copy of beacon software "feel free to download, edit and use" TNX VK6HV
....NOTE... >dot<BASIC files will open in NotePad "As you can see, it draws on other people's work"... details for the QRSS beacon from M1CNK
7) 4SQRP's Cricket I can't wait to try this FET XTAL oscillator and class E final. TNX NM0S
Feel free to download, edit and use my feeble hack of VK6HV's beacon and timing code.
Feel free to download, edit and use my feeble hack of VK6HV's beacon and timing code. My hack also makes 08M2 pin for pin compatible with RockMite U3 12C508 keyer DIP.
John, I added a second 2n7000 at Q2. Same output with 9V as 1 2N7000, but my receive sensativety went up as well as my audio output. Can't wait to try it with 12V. Mark/WQ8S
Cricket 80a mods 40, 30
"Where can I get info on the 40 30 mods? Tnx" George/W2BPI
HAPPY NEW YEAR
and "may the *qrp*force be with you" :>)
David Cripe NMØS
The orignal Cricket is cute, clever and delightful enough to own a couple and I do, but like ALL qrp xcvrs there is a weak spot, here it is the xtal osc.
Since David nm0s touts his new 80-a xtal osc and since I was lQQking for a versital osc for my qrss beacon system I decided to bread board his xtal osc circuit. Then all I did was plug in xtals on hand. His 2n7000 osc also works a delight on 40, 30, 20, 15.
As far as I know ...
I am first to try this:
My 80-a's TX components are on a poke board ...
Output is almost two Watts on 40, 30 and 20 with,
Cavaet 1) 12 Volt power supply
Cavaet 2) Parallel a second 2n7000 (Q2-a) with Q2, note,
Q2 is just an on/off switch not an RF amplifier and
overheats at 12V
Cavaet 3) mod L2, I use xx turns on red T 50-2
Cavaet 4) mod LPF, I use QRPLabs LPF- band-kit
Cavaet 5) 5 V regulator for Q1 es Q3 2n7000 xtal osc
Cavaet 4) mod Q7 (add two resistors and 2n7000 Q7-a) such that Q7 no longer in series with Q2||Q2a (at 12V B+ and QRSS 5 sec dits key down I-R drop too great es Q7 overheats). Q7-a now in series with es keys Q2||Q2a.
Works great for QRSS CW, 5 second dit, 15 sec dah.
QRSS FSCW still under construction, but definitely doable with mod at R6/Q3.
I have not modified my 80-a circuit board yet, but I will, next on the bucket list. . . But first my apologies to David nm0s for mods to such a lovely design and layout. I promise not to destroy your OUTSTANDING 80m L2 / L3 layout, all 80a will remain functional.
If you would like to teach a Cricket to speak QRSS take a pEEk here...
... es you may share my simple hack with whom ever,
I will copy the 4SQRP Group