It IS fun, just be aware that this is a ham frequency rig, which legally requires a ham license. It really is a whole hobby by itself. Antennas are big and kind of a pain. A quarter-wave antenna wire is 10 meters long, with coax. You can actually damage your transmitter final amp (1 transistor) with the wrong (or no) antenna.
So proceed knowing that there's more involved than cheap CB walkie talkies (which may be a better alternative for some). These QRP rigs can be addicting, there are fanatics who "work the world" on a couple of watts, requiring great finesse, high antenna efficiency, and taking advantage of optimal atmospheric conditions.
Curiously, this rig comes with a frequency (7.023 MHz) requiring an amateur EXTRA license (the highest and most difficult to obtain). Per http://kb2hsh.blogspot.com/2014/12/the-chinese-pixie-2-qrp-transceiver.html it makes more sense to switch to a different crystal (7.030 or 7.040) for use with the simplest ham license. There isn't any code requirement or testing, just a written test on basic electronics & radio knowledge and some legal stuff. Many local ham clubs administer the tests for little or nothing.
This is such a thing as unlicensed (FCC Part 15) use. One example of such use is broadcasting Propeller NTSC video across the room on TV channel 3. Here are a couple relevant paragraphs for hobbyist use. Such a transmitter would be classified as an intentional radiator.
§15.5 General conditions of operation.
(a) Persons operating intentional or unintentional radiators shall not be deemed to have any vested or recognizable right to continued use of any given frequency by virtue of prior registration or certification of equipment, or, for power line carrier systems, on the basis of prior notification of use pursuant to §90.35(g) of this chapter.
(b) Operation of an intentional, unintentional, or incidental radiator is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authorized radio station, by another intentional or unintentional radiator, by industrial, scientific and medical (ISM) equipment, or by an incidental radiator.
(c) The operator of a radio frequency device shall be required to cease operating the device upon notification by a Commission representative that the device is causing harmful interference. Operation shall not resume until the condition causing the harmful interference has been corrected.
(d) Intentional radiators that produce Class B emissions (damped wave) are prohibited.
§15.23 Home-built devices.
(a) Equipment authorization is not required for devices that are not marketed, are not constructed from a kit, and are built in quantities of five or less for personal use.
(b) It is recognized that the individual builder of home-built equipment may not possess the means to perform the measurements for determining compliance with the regulations. In this case, the builder is expected to employ good engineering practices to meet the specified technical standards to the greatest extent practicable. The provisions of §15.5 apply to this equipment.
There are further regulations about prohibited bands of operation, antenna restrictions, and radiated field strength. Even then, if you operate within the ham bands without a license, you will be called out by an especially technically savvy group who guard their frequency allotments jealously.
How hard would it be to decode Morse code from the receiver? One would just need to detect the presence or absence of a tone on the speaker output.
Not entirely..
1) Long and short tones
2) Spacing between letters vs spacing between words
3) Bad signal, i.e. parts of the sounds or message are missing
When these are generated by a machine/computer 1) and 2) are consistent, and thus easy to decode, except in the case of 3), where a human can compensate and "hear" the signal even when the signal to noise ratio is pretty bad. With a human operator 2) is not necessarily a big problem anymore because nearly everyone will use a keyer which generates the shorts and the longs for you in a consistent way, with just the right amount of space between letters of a word (freely adjustable by the operator, but at least consistent after that - but the receiver will have to do some initial adaption/calibration). But the spacing between words is still an operator issue. There may even be no clear difference, which means that the receiver must pick out the words from the stream of letters.
The first packet protocols were basically a strictly controlled morse-like protocol and thus easy for the receiving computer to decode (except for 3), unless you add error correction).
How hard would it be to decode Morse code from the receiver? One would just need to detect the presence or absence of a tone on the speaker output.
Not entirely..
1) Long and short tones
2) Spacing between letters vs spacing between words
3) Bad signal, i.e. parts of the sounds or message are missing
When these are generated by a machine/computer 1) and 2) are consistent, and thus easy to decode, except in the case of 3), where a human can compensate and "hear" the signal even when the signal to noise ratio is pretty bad. With a human operator 2) is not necessarily a big problem anymore because nearly everyone will use a keyer which generates the shorts and the longs for you in a consistent way, with just the right amount of space between letters of a word (freely adjustable by the operator, but at least consistent after that - but the receiver will have to do some initial adaption/calibration). But the spacing between words is still an operator issue. There may even be no clear difference, which means that the receiver must pick out the words from the stream of letters.
The first packet protocols were basically a strictly controlled morse-like protocol and thus easy for the receiving computer to decode (except for 3), unless you add error correction).
1 and 2 are something I feel I could deal with even if trying to receive a human-generated signal. It is 3 I would worry about but doesn't this just require a notch filter at the appropriate frequency?
There are many software programs which decode Morse. I played around with the CWget software a few years back and was pretty impressed: http://www.dxsoft.com/en/products/cwget/
But IMHO learning Morse is a satisfying experience most anyone can master. Back in my day you had to listen to cassette tapes (or records) to practice code at various speeds, and/or listen to W1AW radio broadcasts. Today, just click on Youtube for a whole multimedia experience.
Secret confession: I finished assembling them 6/29 but haven't applied power yet. I've got BIG BIG plans. But better hang on to your cellphone for a few more days, just to be safe.
Aw c'mon, at least test the receiver if you don't want to fire up the tx.
Your logic is irrefutable.
I powered up two boards today. Equipped them with small dummy loads. When keyed, they clearly generate RF. I can tell because the capacitively-coupled dummy loads get warm with time. Furthermore, I can clearly hear a transmitting board on a receiving board. But I haven't achieved a dulcet tone yet. It's more of a rasp. Clipping, probably. I think I need more physical separation, despite dummy loads (not using lightbulbs!). When my daughters get home from a parade they're attending, perhaps I can recruit them to help me test range and audio quality.
Of course, after the parade come the fireworks. It may be a late test.
1) Long and short tones
2) Spacing between letters vs spacing between words
3) Bad signal, i.e. parts of the sounds or message are missing
[..]
1 and 2 are something I feel I could deal with even if trying to receive a human-generated signal. It is 3 I would worry about but doesn't this just require a notch filter at the appropriate frequency?
It's not so much about noise level (which can be filtered), it's more about dropouts and fading. A human operator (at least an experienced one) will hear the words, not the individual dah-di-dah-da characters, and the brain fills in the missing/fading parts. But when the signal is steady it can be handled by a computer (hardware and/or software), and it can be an interesting challenge. Adaptive filters and whatnot.
Back when I worked CW I used a Timewave active filter. Did a wonderful job of pulling weak stations out of the dirt. A TNC could decode code if was near perfect timming by a good fist!
One of the coolest and most useful circuits I ever built from Popular Electronics was an "Audio Q-Multiplier", IIRC in the Hobby Scene department. It was a simple one-transistor audio notch filter that worked REALLY well for with my Heathkit HR-10B which had decent sensitivity but poor selectivity. I wish I still had that circuit or schematic to share. Most likely it was a circuit that was nearly in oscillation and just needed a push at the resonant frequency.
This might be the circuit, it looks like the graphics are lifted right out of the mid-70's, back when I was bangin'.
One of these days I'll pull out my Tempo 2020 and test these boards with a real HF rig, but in the meantime I'm just sending and receiving between Pixie 4.3 boards.
The separation tests worked great, which is to say these modules provide perfectly acceptable bidirectional CW communication. That itself is really groovy, especially with such simple circuits. Pushing the Rx crystal slightly does indeed change the sidetone frequency as expected. But I hear nothing like a pure sinewave. The tones, at any frequency, are rich in harmonics. Heard thru my Panasonic headphones, I would describe their sound as reedy.
That's why I need to break out the scope, signal generator, and HF rig, and really see what is going on. More sacrifice!
BTW, the ceramic caps provided in the kit match well the schematic insofar as the RF circuitry is concerned. But the supply filtering and audio output capacitors in the schematic don't match what was provided in the kits. So I used my own caps to build the boards according to the schematic. It may be that the audio would sound differently if, for example, C10 and C11 were the values supplied in the kit and not the values specified in the schematic.
Rather than monkey with part values though, I'm more inclined to keep the boards as they are and proceed forward with my mad plans that involve Propellers and righteously busy cogs. Why swap out a capacitor when you can write 1000 lines of code?
Thanks for the build info. I haven't had the pleasure yet...
Looking at other sellers of this kit, there appear to be a few variations between boards. These have simple 2-pin connectors for antenna and power, where others have a BNC connector and a barrel jack. And these have a sidetone beeper and power (?) LED where others don't. Dealer's choice.
Thanks for the build info. I haven't had the pleasure yet...
I'll be interested to read about your experiences with these boards. In fact I'm just waiting for you to do all the detailed, inspired, difficult investigation.
Yeah, I noticed the other day there were older designs with BNC connectors. I'm quite happy with what I have and what I paid for them. Eschewing the connector altogether, I soldered the dummy loads straight to the pads in an effort to minimize untoward emanations.
I'm surprised how expensive a simple Morse code key is on Ebay. Rusty old keys that sold for $5 at Radio Shack 20 years ago are selling for $30-40! That seems a lot for a N.O. momentary switch. There's an opportunity for someone.
I really love the idea of using dirt-cheap power MOSFETs as HF amplifiers. I still remember what it was like to make and tune an 80M power amplifier using an output tube like the 6L6 - magical but also real PITA. And expensive, especially if you hadn't yet acquired a large parts collection.
Agreed, vacuum tubes can surely be a PITA: microphonics, thermal drift aplenty, and when inevitably replaced, some circuits require retuning. But when they're tuned in, turned on, and toned up (see reference!) there's a special magic in their glow and the smell of warm vintage electronics.
Much like my 1977 Gottleib "Jungle Queen" pinball game. It's the last year before they went electronic. The vintage plywood case is chock full of warm #47 incandescent lamps, relays, solenoids, rotating contactors, and miles of old braided wiring. That characteristic warm dusty plywood smell wafts gently from the game just a few moments after being turned on. Aromatherapy at its finest!
I was hoping to find one of the ones that glowed purple, but that was the best I could find on GIS in short order for a lit regulator. Most GIS pics of tube equipment seem to be of newish audio stuff which uses modern power supply components and rows of identical miniature tubes, booooring. And all the pics of chassis mount metal can electrolytic caps showed them being disassembled to reburbish by sticking a modern cap inside the can.
Comments
So proceed knowing that there's more involved than cheap CB walkie talkies (which may be a better alternative for some). These QRP rigs can be addicting, there are fanatics who "work the world" on a couple of watts, requiring great finesse, high antenna efficiency, and taking advantage of optimal atmospheric conditions.
Curiously, this rig comes with a frequency (7.023 MHz) requiring an amateur EXTRA license (the highest and most difficult to obtain). Per http://kb2hsh.blogspot.com/2014/12/the-chinese-pixie-2-qrp-transceiver.html it makes more sense to switch to a different crystal (7.030 or 7.040) for use with the simplest ham license. There isn't any code requirement or testing, just a written test on basic electronics & radio knowledge and some legal stuff. Many local ham clubs administer the tests for little or nothing.
I Just ordered this ten-pack of the 7.030 crystals soon if anybody wants one: http://www.ebay.com/itm/QRP-Ham-Radio-Crystals-HC49-S-7-030MHz-10-pack-/282076141641 I'll have 8 to spare!
Probably ~$1.50 each shipped if I can ship them into a regular first-class envelope. Yeah, half the cost of the whole transceiver!
(a) Persons operating intentional or unintentional radiators shall not be deemed to have any vested or recognizable right to continued use of any given frequency by virtue of prior registration or certification of equipment, or, for power line carrier systems, on the basis of prior notification of use pursuant to §90.35(g) of this chapter.
(b) Operation of an intentional, unintentional, or incidental radiator is subject to the conditions that no harmful interference is caused and that interference must be accepted that may be caused by the operation of an authorized radio station, by another intentional or unintentional radiator, by industrial, scientific and medical (ISM) equipment, or by an incidental radiator.
(c) The operator of a radio frequency device shall be required to cease operating the device upon notification by a Commission representative that the device is causing harmful interference. Operation shall not resume until the condition causing the harmful interference has been corrected.
(d) Intentional radiators that produce Class B emissions (damped wave) are prohibited.
§15.23 Home-built devices.
(a) Equipment authorization is not required for devices that are not marketed, are not constructed from a kit, and are built in quantities of five or less for personal use.
(b) It is recognized that the individual builder of home-built equipment may not possess the means to perform the measurements for determining compliance with the regulations. In this case, the builder is expected to employ good engineering practices to meet the specified technical standards to the greatest extent practicable. The provisions of §15.5 apply to this equipment.
There are further regulations about prohibited bands of operation, antenna restrictions, and radiated field strength. Even then, if you operate within the ham bands without a license, you will be called out by an especially technically savvy group who guard their frequency allotments jealously.
-Phil
1) Long and short tones
2) Spacing between letters vs spacing between words
3) Bad signal, i.e. parts of the sounds or message are missing
When these are generated by a machine/computer 1) and 2) are consistent, and thus easy to decode, except in the case of 3), where a human can compensate and "hear" the signal even when the signal to noise ratio is pretty bad. With a human operator 2) is not necessarily a big problem anymore because nearly everyone will use a keyer which generates the shorts and the longs for you in a consistent way, with just the right amount of space between letters of a word (freely adjustable by the operator, but at least consistent after that - but the receiver will have to do some initial adaption/calibration). But the spacing between words is still an operator issue. There may even be no clear difference, which means that the receiver must pick out the words from the stream of letters.
The first packet protocols were basically a strictly controlled morse-like protocol and thus easy for the receiving computer to decode (except for 3), unless you add error correction).
But IMHO learning Morse is a satisfying experience most anyone can master. Back in my day you had to listen to cassette tapes (or records) to practice code at various speeds, and/or listen to W1AW radio broadcasts. Today, just click on Youtube for a whole multimedia experience.
3 words per minute:
Your logic is irrefutable.
I powered up two boards today. Equipped them with small dummy loads. When keyed, they clearly generate RF. I can tell because the capacitively-coupled dummy loads get warm with time. Furthermore, I can clearly hear a transmitting board on a receiving board. But I haven't achieved a dulcet tone yet. It's more of a rasp. Clipping, probably. I think I need more physical separation, despite dummy loads (not using lightbulbs!). When my daughters get home from a parade they're attending, perhaps I can recruit them to help me test range and audio quality.
Of course, after the parade come the fireworks. It may be a late test.
Science requires sacrifice!
This might be the circuit, it looks like the graphics are lifted right out of the mid-70's, back when I was bangin'.
http://www.tradeofic.com/Circuit/3768-AUDIO_Q_MULTIPLIER.html
also http://www.next.gr/audio/audio-filters/q-multiplier-filter-circuit-l11793.html
Edit: A more modern (741 op amp) version also from PE circa 1989 at http://www.qsl.net/kc6wdk/QRP/qmultiplier.htm
LOL
One of these days I'll pull out my Tempo 2020 and test these boards with a real HF rig, but in the meantime I'm just sending and receiving between Pixie 4.3 boards.
The separation tests worked great, which is to say these modules provide perfectly acceptable bidirectional CW communication. That itself is really groovy, especially with such simple circuits. Pushing the Rx crystal slightly does indeed change the sidetone frequency as expected. But I hear nothing like a pure sinewave. The tones, at any frequency, are rich in harmonics. Heard thru my Panasonic headphones, I would describe their sound as reedy.
That's why I need to break out the scope, signal generator, and HF rig, and really see what is going on. More sacrifice!
BTW, the ceramic caps provided in the kit match well the schematic insofar as the RF circuitry is concerned. But the supply filtering and audio output capacitors in the schematic don't match what was provided in the kits. So I used my own caps to build the boards according to the schematic. It may be that the audio would sound differently if, for example, C10 and C11 were the values supplied in the kit and not the values specified in the schematic.
Rather than monkey with part values though, I'm more inclined to keep the boards as they are and proceed forward with my mad plans that involve Propellers and righteously busy cogs. Why swap out a capacitor when you can write 1000 lines of code?
Looking at other sellers of this kit, there appear to be a few variations between boards. These have simple 2-pin connectors for antenna and power, where others have a BNC connector and a barrel jack. And these have a sidetone beeper and power (?) LED where others don't. Dealer's choice.
I'll be interested to read about your experiences with these boards. In fact I'm just waiting for you to do all the detailed, inspired, difficult investigation.
Yeah, I noticed the other day there were older designs with BNC connectors. I'm quite happy with what I have and what I paid for them. Eschewing the connector altogether, I soldered the dummy loads straight to the pads in an effort to minimize untoward emanations.
I'm surprised how expensive a simple Morse code key is on Ebay. Rusty old keys that sold for $5 at Radio Shack 20 years ago are selling for $30-40! That seems a lot for a N.O. momentary switch. There's an opportunity for someone.
Real old school: http://www.ebay.com/itm/Vintage-Telegraph-Key-Ham-Radio-Morse-Code-Wood-Mounted-/191894401726
Morse code cheat chart: http://www.vicfieger.com/e-ohaver.html
See also http://www.ebay.com/itm/New-CW-Mores-Code-Decoder-Chart-Medal-Commemorative-Coin-Gift-Prize/351795544429
$11.45 for a hardware decoder with LCD! http://www.banggood.com/Morse-Code-Reader-CW-Decoder-Morse-code-Translator-Ham-Radio-Essential-Module-p-1026637.html?currency=USD&createTmp=1&utm_source=ebay&utm_medium=cpc&utm_content=saul&utm_campaign=SKU336763-US&ebay I still say this would be a great Stamp or Prop project, but for that price, dive right in.
I really love the idea of using dirt-cheap power MOSFETs as HF amplifiers.
-Phil
I remember when this was brought up in 2010:
http://forums.parallax.com/discussion/127606/knowledge-poll-no-googling/p1
Answered correctly. Still got some.
Pretty cool, looks like a nightmare to repair.
That's part of a would be power supply, add a transformer, bridge rectifier, voltage regulator, and couple of electrolytics.
Sorry, a change to the BOM. I fogot the fuse holder, very important.
Here ya go!
EDIT: I love the lit regulator tube.
I have one of those. Plus 2 unbuilt HW-9s. Maybe it's time to sell. My evil plan to corner the unbuilt Heathkit market is coming to fruition!
-Tor