KnightsQRSS Blog

Observations on Hans' QRSS Kit

2011-10-23T13:36:00.000-07:00

Dear reader!
I was surprised. I can't recall when there was the last spontaneous contribution for this blog. No, the 12V mod of Hans' kit was not a direct contribution, I offered to host the document.
Not the case here, Kevin (ZL1UJG) has some interesting information to share. For sure, in the interest of the QRSS community, I will host this document too.
So, here it is: http://qsl.net/dl1gsj/The_Molded_Mud_Saga.pdf
Guys, if you want to keep this blog and the QRSS community alive, contribute! Presently I personally have neither time nor energy to keep up posting fresh information without your help.
In the name of Kevin, 73 de Joachim

backup

2011-08-21T10:11:00.001-07:00

I revived the KnightsQRSS blog. There is some pricetag on it however... 90% of the posts are written by myself... that was not the idea, in particular since I got my own blog.
Hence, the pricetag being, contributions contributions contributions.....

Using a Hans Summers QRSS TX on 12v by Kevin Murphy ZL1UJG

2011-02-19T14:24:00.000-08:00

Kevin ZL1UJG announced on the KnightsQRSS-list that he modified a Hans Summers QRSS MEPT and will publish his results in a PDF-file (see end of this posting).

ZL1UJG's modified 40m MEPT

I am pleased that the KnightsQRSS-blog may host a copy of said document.
Kevin nicely explains how to modify the "power amplifier" to a different voltage. In other words, the modification, moving the supply voltage from 5 to 12V, will increase the output power of the MEPT. The 80, 40 and 30m bands are covered.

I would like to thank Kevin for his excellent contribution, which can be downloaded by clicking here.
Information on how to contact the author can be found at the bottom of the document.

HowTo Setup a QRSS Grabber

2010-11-14T05:26:00.000-08:00

Why setup a grabber?

Spectrum grabbers are an essential part of the QRSS-game. What good is a MEPT or beacon when there are no provision to receive its signal? For scheduled experiments, which are done regularly, require that the transmitting and receiving stations appoint in frequency and time. Automated grabbers allow transmitter operators to experiment whenever wished. Additionally, 24/7 grabbers allow propagation studies.

What is needed?

I would not like to emphasis any particular importance to particular parts of an automated online grabber system. To setup a grabber, one needs:

an aerial
a receiver
a decoupled audio connection
a computer with a soundcard
software
internet connectivity

One thing I am not to discuss in any detail: internet connectivity. The average grabber make use of the typical commercial providers. However, other solutions are conceivable, such as high speed packet radio.

In the following sections, I would to demonstrate a couple of options one has to build a QRSS online grabber.

The Aerial

The most important property of a good grabber aerial is not gain but the capability to reject local, i.e. electrostatics from hairdryers etc., at least in an urban environment. The best aerial, however, is the one that works for you.
When deciding for a particular aerial, one needs to consider a few things:
* What do I like to receive, DX or NVIS?
* How much space to I have?
* How high may I build?
* Mono of multi-band?
* Omnidirectional of directional?

Lets have a look at the possibilities (note that this is not a complete list, neither in aerial types, nor in properties):

* Dipole: directional, needs half the wavelength in length, mono band (multi-band under certain conditions, e.g. 30m/10m), hang it high: DX, hang it low: NVIS, picks up local noise easily

* Sloping Dipole: directional, picks up local noise easily

* Inverted V: omnidirectional, needs less than half the wavelength in length, mono band (multi-band under certain conditions, e.g. 30m/10m), hang it high: DX, hang it low: NVIS, picks up local noise easily

* Vertical (full size): omnidirectional, needs half the wavelength in hight, mono band (multi-band under certain conditions, e.g. 30m/10m), DX, picks up local noise easily

* Trapped Dipole: multi-band, for the rest, same as dipole

* Trapped Inverted V: multi-band, for the rest, same as Inverted V

* Trapped Vertical: multi-band, for the rest, same as full size Vertical

* Full Size Vertical Loop: needs a lot of hight, low noise, directional

* Full Size Horizontal Loop: needs a lot of space, low noise, omnidirectional

* Beverage Antenna: directional, very low noise, very very long, DX

* Rhombic Antenna: directional, low noise, requires a lot of space, DX

* T2FD (Terminated Tilted Folded Dipole): low noise, multi-band, requires specific heights and lengths

* Vertical Magnetic Loop: very small, very low noise, directional

* Horizontal Magnetic Loop: very small, very low noise, omni-directional, requires to be put to some hight

* Frame Antenna: small, low noise, directional, good for lower frequencies

* Distributed Capacitance Twisted Loop (DCTL) Antenna: (similar to Frame Antennae, but for somewhat higher frequencies) mono band, directional, low noise, very transportable, very cheap to make, small

* Rock Loop: very small, directional, very low noise

* E-Probe aka Mini Whip: all band, picks up noise brilliantly and hence requires to be outdoors as high a possible, very very small, omnidirectional

* Shielded Magnetic Loop: very low noise, may need some amplification, very small, directional

* Wideband Small Active Loop: low noise, small

There are certainly many more options, however, I would like to point out that directivity is generally not a good thing for an antenna for a 24/7 online grabber, since one never knows who is going to fire up their transmitters and from where...

The Receiver

This topic carries even more options, there are hundreds of possible solution, so, I would like to discuss the receivers I experimented with. Every list is in no particular order.

Commercial receivers:
AOR AR3030, Sangean ATS-909, Sony ICF-7600G, Yaesu FRG-7700, Yaesu FRG-100, Target/NASA HF-3, AKAI APW20

Commercial transceivers:
Kenwood TS-850, Kenwood TS-440, Kenwood TKM-707, Yaesu FT-817, Icom IC-703, Icom IC-M700TY, Icom IC-M710

Homebrew/Kits:
K1SWL's Rock Mite, K1SWL's PSK-Warbler, N3ZI's General Coverage Communications Receiver, PA1GSJ's Subharmonic DC-RX, KB9YIG's SofRock lite
A remark on home-brew designs: it seem very tempting to build a minimal receiver with the famous NE612. However, in a direct conversion design, one should not use the internal oscillator. The oscillator will load the mixer unnecessarily, reducing the receiver's performance. An external local oscillator is therefore recommended.

Setting up the receiver:
* The receiver should be setup to the upper side-band.
* My experiments revealed that the beat frequency should be somewhat on the higher end. It seems that the sampling results using sound cards are best between 1kHz and 4kHz.
* Receivers, such as the AR3030, being operated in a manner as professional gear is operated, the beat frequency is adjustable, although not programmable. It is however important to know all frequencies (l.o., i.f., b.f.o.) precisely in order to provide an accurate spectrum. The bfo should therefore be calibrated using a frequency normal, such as WWV.
* Ham Radio Receivers set to USB should be right on frequency. Example, assume we want to receive a 7000800Hz carrier, a ham radio receiver set to 7000.000kHz should receive an 800Hz tone. For better sampling results, the receiver should therefore be set to 6999.000kHz so that the receiver will provide a 1.8kHz audio signal.
* Target/NASA HF-3: This particular receiver is made for yacht-men. It shows very good performance and the stability is OK after some warm-up. However, to make frequency dial easy for sailors, a 2kHz beat-offset is built-in. This has something to do with nautical frequency listings.... To recycle the above example, the HF-3 needs to be set to 7001kHz in order to receive out 7000800Hz carrier at 1.8kHz audio.
* World-Band Receivers w/ bfo: These products are not made for this sort of task. However, the ATS-909 does a good job, frequency fine tuning is done digitally, which is a big advantage. The APW20 and ICF-7600G employ fine tuning with a potentiometer, that makes the frequency less reliable. Additionally, my ICF show some frequency drift.

Since it is a good performer, receives from 30kHz to 30MHz, is comparably cheap and has low power consumption, I recommend the Target/NASA HF-3 for a newcomer to grabbing. Additionally, the present HF-3 model can feed an active aerial, which comes along handy when using an E-probe. Downside, fine tuning is done with a potentiometer called "CLARIFY". This receiver has got a relatively wide side-band filter, allowing to clearly hear zero-beat.
With the HF-3 as an example, I would like to disclose some tricks, which are equally valid for other receivers.
Again, as in the example above, a 7000800Hz carrier is to be received.
The HF-3 should be set to 7001 (kHz), which represents a 6999kHz zero-beat frequency; it is advisable to store this in a memory channel.
In order to control fine tune calibration, one needs to tune to a close by carrier having a known, stable frequency; for 40m I use DW-Radio at 6075kHz. With the carrier set to zero-beat, with the HF-3 this means 2kHz above to 6077kHz, the CLARIFY knob is tweaked until zero beat occurs. For convenience, I have stored 6077 (kHz) in another memory channel. Calibration control is made very simple in that way.

As a second, real life example, this would an easy setup for receiving the 600m band.

Target HF3 w/ YAESU FRT-7700

This setup obviously receives 501kHz zero-beat. Since the built-in SSB filter is about 6kHz wide, the receiver provides a good grabbing coverage from 502kHz to 506kHz, enough to cover the most of the usable band. Calibration is done at 648kHz in this case.
The YAESU FRT-7700 is a good and relatively inexpensive add-on to a grabber setup.

Decoupled Audio Cable

This is a very important point. In a computer, all sorts of r.f. frequencies are used for all sorts of tasks. Shielding those carriers by 100% is nearly impossible, however, there is no need to feed those into the receiver directly either. Decoupling is usually done by a 1:1 audio transformer.

Computer & Sound Card

Two points here. With the receiver having low power consumption, the next place to save energy is the computer, which turns the tone into images. The computer's job is not particularly demanding, processors like the Intel Atom series are absolutely up to the task.
It is desirable to use a very low noise sound card. However, the more additional components are present in the computer, the more energy it uses. For reasons of energy efficiency, I am using the (two) built-in sound cards. Additionally I did some experiments with ultra-cheap USB sound-plugs, they work too.

Software

A grabber computer has got 2 main tasks:
* convert received audio into spectral images
* upload said images to a webpage
In this section, I will discuss software for Microsoft Windows based computers only! The programs may or may not work in WINE. I am aware of other OS, maybe some one else would be so kind to write a HowTo for OS-X, BSD or Linux.

Creating Spectra
The most popular and versatile program is DL4YHF's SpectrumLab. SpectrumLab also allows I/Q-SDR reception with KB9YIG's SoftRock receivers.
Another program regularly used is i2PHD's Argo.
Last but not least, there is a new kid on the block: AJ4VD's QRSS VD. Scott's software also uploads images and there are averaging options.

Uploading Images
Almost everybody, including me, seems to be using ON7YD's ArgoUpload.

The Webpage

For ease of operation, a provider should be selected which allows ftp-upload. Although this is entirely up to the reader, I would like to draw the attention to http://www.qsl.net/ which provides free web-space for amateur radio use. Page maintenance on qsl.net is done by ftp, hence, ideal for our grabber setups.

SW+ Transceivers for QRSS

2010-11-07T05:05:00.000-08:00

Check out my blog to see more details about possible qrss-mods for the SW+ Series Transceivers.
73, Joachim

Full Duplex QRSS TRX Idea

2010-10-17T10:54:00.000-07:00

This has been in my head for some time... What about in-band full duplex QRSSing?
Some preconditions we have to look at. For a successful slow QSO, we need to assume condx of a single band, so that both stations can receive the counterpart equally. TX during RX in one band at the same time is a challenge even on the 2m-band. So, what can be done?

The problems, I figure, are more on the receiving side of the design. So here are some preliminary ideas that came to my mind:

frequencies in one band, the furthest possible apart
a very narrow-band RX antenna, e.g. a high Q magnetic loop
a crystal notch filter for the TX frequency
a crystal front end filter

I have no idea if this would actually work...
However, for experimentation, there are a couple of possible frequencies (cheap crystals available).

80m: 3.500MHz & 3.6864MHz
40m: 7.000MHz & 7.15909MHz
20m: 14.000MHz & 14.31818MHz
10m: 28.188MHz & 28.636MHz

The high crystals for 40m and 10m may be a little difficult to find, check DigiKey. All others are either standard, or available at GenesisRadio. Remember, we need a crystal for every QRG, at least for the notch filter!

For me, the obvious choice for making a full duplex QRSS transceiver would be K1SWL's 80m-Warbler. I could show that the Warbler is quite potent on 40m when modified. I would assume that the kit could equally modified for the 20m band.
Based on the Warblers, one would need two per band. The Warblers make nice transmitters too...
Unfortunately, the Warbler kit is retired by now.

Another approach could be the use of a superhet receiver with a (switchable) notch filter in the front-end, remember, it is all about keeping the TX out of the RX when going full duplex.

17m tests

2010-05-22T13:51:00.000-07:00

Dave WA5DJJ has started running some tests on 17m with his new DDS-60/Arduino MEPT, based on the design by Ross KB1KGA
Fear not about building a DDS-60 as you can now get them ready built if you desire :)

Back in January I posted a list of QRSS frequencies on this Blog and elsewhere, 18.1089 being "untested" well I can say that this is looking a fine choice.

NE612 MEPT/Grabber

2010-04-13T12:24:00.000-07:00

N3ZI offers nice little PCBs (click here) for superhet receivers.
It appears that those little receivers can easily be turned into transmitters. I got some ideas in my mind, which I will successively add to this post, so, stay tuned.

For QRSS I would favor a 10.000MHz I.F. with resulting QRGs: 7000800Hz, 14000800Hz, 21000800Hz and 28000800Hz. Crystals (oscillators) are available for 3MHz, 4MHz, 11MHz and 18MHz.
More cheap crystal combinations could be found on my web-page. Note that only pairs with M=1 are "drop in" compatible with N3ZI's PCBs.
One nice option appears to be a dedicated 17m WSPR receiver, or maybe even a transceiver. This design would make use of a 8.000MHz I.F. and a 10.106MHz crystal (30m QRP). A tiny bit of pull and the carrier frequency should be 18.1046MHz.

600m is easily available with the following crystals: 5.000MHz - 4.500MHz - 4.000MHz - 3.500MHz - 3.000MHz - 2.500MHz - 2.000Mhz.
Remember, the subtractive mixing compensates for thermal drift of the oscillators.

Transmit?? you may ask yourself... Yes, I believe that Douglas' PCBs are equally suitable for generating a single side band signal. Please have a look to the schematics on N3ZI's webpage.
A modification to a transmitter, in my view, could be the following:

feeding an AF signal to pin 1 of U1, the input filter and transformer make place for an AF network
X6 should have the same frequency as the filter-crystals
U2 is now a converter, thus, X5 serves the LO
Q2 a buffer, C17 should therefore be replaced by a some means for linearizing Q2
C22's capacitance should definitely be reduced

I figure that this PCB, modified for transmit, together with a simple MP3-player, makes an excellent base for a MEPT in combination.

Two PCBs will provide a nice and easy transceiver. One PCB just like intended, the other modified for transmit as shown above. Here, some additional considerations seem appropriate:

feed the BFO from the RX board to U1 of the TX board, alternatively use an external BFO
feed the LO from the RX board to U2 of the TX board, alternatively use an external LO or VFO

As soon as I got the first results, I will write an update on this site. Stay tuned....

PSK-Warbler 40m mod

2010-03-11T16:12:00.000-08:00

Unpatiently I was waiting for my PSK-Warbler kit to arrive. Just in time, it did. Building it was very very easy, modifying it was relatively straight forward. Modifying? - you may ask yourself, yes, even a nice rig like the Warbler may be modified.

The Plan

Originally the Warbler is designed for 80m using color burst crystals for TX and RX ladder filters. For reasons of W1AW, the Warbler is using a b.f.o. above the filters' frequencies. Given that the Warblers are supposed to be used for PSK, this is an option, PSK-software can be set to operate on the lower side band.

The modification described here is supposed to get the Warbler running on 40m, with as few changes as possible. The modified Warbler should also serve as a WSPR transceiver. Actually, this was the main point on doing this mod in the first place.

The Modification

This is what I did (please grab a circuit diagram):

the b.f.o. xtal changed to 7.038MHz
all filter xtals changed to 7.040MHz
C13 -> 47pF
L3 -> 10µH
C10 -> 100pF
C11,C12 -> 470pF
L2 -> 1.1µH (17 turns on T37-2)
C3 replaced by 2.2µH and a polyvaricon-trimmer in series

Points 1. and 2. are somewhat obvious, I believe. The crystals are available from Rich N4ESS.

Points 3. and 4. change the passband frequency if the C13-L3 series resonance circuit of the receiver to the 40m band.

Point 5. matches the coupling between driver and final to the operation frequency. This part of the mod may have to be revisited.

Points 6. and 7. bring the low pass filter response to something above the 40m band.

Point 8. allows for variable pull of the b.f.o. to 7038600Hz. I used a combination of a polyvaricon-trimmer (4...18pF, I believe) and a 10pF NP0 capacitor in parallel. This is certainly the part of the modification in which some experimentation is required, since tolerances and different cuts or series capacitances of the b.f.o. crystal plays a role in that game.

First Results

As I mentioned before, WSPR is certainly a main point for the little great rig. The first night out, RX only, at a hidden G5RV-jr, the following are among the decoded stations: VK6POP (14190km), VK6BN (14188km), W4PJZ (6781km), NB3N (6137kM), K4YO (5954km).

I did TX, however, only once for testing, with very low power. For regular WSPRing, an enclosure would be required. Presently, the Warbler is laying open on the table, next to the grabber computer.

Next to WSPR many other modes were detected on the spectra, e.g. several types of PSK and even JT65. I am sure that the 40m Warbler will be a big hit! Dave K1SWL may put more on his webpage, stay tuned!

Other Option(s)
As long as there are crystals available, the Warbler could easily be modified to any other band, e.g. 30m using 10.140 crystals. This would offer us another QRSS kit, this time for audio keying. Again, a kit offers RX and TX options for QRSS on very affordable costs and essentially no build time.

Really weak signals..

2010-02-19T12:56:00.000-08:00

OK, so I have mentioned and use Triangles a lot :) here is an example of them on the KL1X Grabber in Alaska, they would beat FSKCW hands down under these conditions, extreme Multipath.
The AVK id easily readable, working conditions - 500mW into a sloping Dipole, Apex at 8m AGL

Click the image to see the original.

Local capture for reference:

Colin

30m QRSS Beacon, revision #4

2010-02-14T03:53:00.000-08:00

I get asked numerous times about one of my MEPT's I use on 30m, which is capable of sending all QRSS modes and some interesting graphical modes, HELL, SQUELL, Triangles and so on. How? I use a CWKTiny keyer by DL6JAN

The basic design I came up with a few years ago (now in its 4th revision and box) and has the addition of PTT switching to get the full benefit from the keyer.
The RF side of it uses 2N2222a + 2N3819 for the Oscillator/Buffer which is in its own box, this drives a 2N2222a > 2N3866 PA ~ 500mW after the LPF.
It's built Manhattan style and very reliable indeed.

For added "long term drift" I use a DB6NT QH40 heater but I still need to work on this, change some Caps in the oscillator :-)

I have used the MEPT on 20m down to 160m, with the necessary changes made to filters and oscillator. You will find getting the frequency to shift (frequency and keying shift) down on 160/80m a challenge, maybe something other than a Colpitts oscillator would help here?

Some Graphical mode examples, Triangles, FATCW, SlantCW:

You can also invent your own unique waveforms as well :

KnightsQRSS Clipboard usage.

2010-01-31T07:00:00.000-08:00

I would hazard a guess that at least 50% of stations listed on the "Clipboard" are not QRV. The ones known (to me) that are QRV:
IQ4FJ/p, G3ZJO (both bands), VK2ZAY (details are old but I have seen him on VK7ZL's grabber recently) IZ1KXQ, ON4NIC, IQ2DP.

A side note to this is there are stations QRV in the USA who are not on the Clipboard..

The Clipboard can be very useful if kept up to date, old entries can easily be hidden when the station goes QRT, of course this relies on the op remembering. I cannot see any easy way around this unless resorting to Email reminders?
We all can do tabbed browsing now, I have 5 tabs that automaticly open when I start my browser (FireFox) one of course is the Clipboard.

Sadly the RSS feed has not worked in a long time (for me) a facility I find ever so useful. I am a big RSS fan :)

Personally I don't think many actually use the Clipboard which is a great shame to this valuable tool.

Colin

Rock-Mite 80 QRSS modification

2010-01-31T03:46:00.000-08:00

Here's what you wanna do when going for a Rock-Mite-80-QRSS-mept/grabber.

get a Rock-Mite 80 kit from Dave
get two 3.579545MHz crystals
get one 4.7pF and on 22pF capacitor
build the kit, leaving out C8 (beep beep)
for C12, use 4.7pF in place of 47pF (reduces chirp)
for C2, use 22pF in place of 33pF (lifts filter response)
get a 8-pin PIC (to replace U3) and program it as wanted

The reduced coupling from the oscillator to the (keyed) buffer results in lower output power. 4.7pF to me seems the working compromise. I tried all of the following values (in order of the experimentation timeline): 47pF (original - severe chirp, PA becomes hot), 27pF (still intolerable chirp, PA warms slightly up), 2.2pF (no chirp at all, nearly no power), 18pF (chirp), 10pF (chirp), 7.5pF (still too much chirp) and finally 4.7pF.

Optional, a 10V Zener diode could be dropped into D5's empty place. This will lower the "upper" qrg by about 200Hz, further reducing chirp.

For the mode, I would advice A1A with QSK, for timing, QRSS6 will do just fine.

Programming: With no further hardware modification, an 8pin PIC, such as the 12F629 can be used.

GPIO4 low will provide the varicap diode with 12V, resulting in the higher frequency, which is used for TX.

GPIO5 high will key the buffer and the PA.

I found that it is sufficient to low GPIO4 just before keying the transmitter. Returning GPIO4 to high directly after transmission allows for full QSK. No additional chirp in the TX signal.

To also receive, e.g. as a grabber, my program receives for 10min before TXing the message again.

I did all that, it works, concept proven.... hope to see more signals on the color burst frequency and more grabbers on the internet in the close future.

PS: Somewhat obvious... this mod will work on any frequency we got crystals for... e.g. 30m.

The GenesisRadio Q5 TX sending QRSS (on/off keying) before and after my modification.

2010-01-25T14:17:00.000-08:00

I thought maybe I should post a local Capture of the Q5 running on 3.579,800 this evening. The mode is QRSS5 (on/off keying) with the simple resistor mod mentioned in my previous Q5 mod post.

Before the mod:

After the mod:

Quite good isn't it considering its strung out over the test bench :)

Colin

Getting started with QRSS

2010-01-22T07:13:00.000-08:00

What is QRSS ?

To put it quite simply, the QRSS mode is the transmission and reception of slow speed Morse transmissions at the lowest possible levels of power. The most common speed currently in use is QRSS3, where the length of a dot is equal to a transmission of about three seconds.

Most amateurs transmit a traditional constant wave (or CW) signal, which is very much like holding down the knob of your Morse key for a lot longer than usual. Others favour FSKCW, where the oscillator is shifted very slightly to produce a higher signal frequency for the mark (or positive signal). The shift, however, is very small, usually only a matter of a few Hertz.

Some of the more industrious and technically brilliant amongst us have even used this mode to transmit Hell Schreiber signals. In graphical terms, this can appear as a series of readable characters which are displayed on a computer monitor.

There are a significant number of amateurs around the world currently conducting experiments with QRSS on most of the HF bands. Many are designing and building lower power transmitters and standalone receivers specifically for this purpose. The receivers are connected to the input of a computer soundcard. Programs, such as Argo, are then used to analyse a very small portion of the amateur band in use, for example, 30 metres, and then to display in a graphical form, the signals which are being received.

The image above shows a typical output of Argo during the middle of the day. It covers the segment from 10.140000 to 10.140100 where you can clearly see the activity of a number of amateurs from around Europe.

Why would anyone want to use QRSS ?

Since the 1960’s we have seen a move away from broadband transmissions, such as Amplitude Modulation, to Frequency Modulation and Single Side Band. In the past ten years we have seen the emergence of even narrower band transmissions and an explosion in the use of digital modes. The narrowest of signals, Morse, has stood the test of time, often being used to establish communications where all else fails.

QRSS is both fun and technically demanding at the same time. Over the past two years more and more amateurs have tried their hand at broadcasting their miniscule signals and have been astounded that they have been heard at great distances. For many, I am sure, this is the cornerstone of QRSS: doing more with less.

What you need to receive QRSS

If you own an HF receiver and a standard ‘home’ computer, the chances are that you could be and running within an hour. The audio output from your receiver is fed to the input of your computer’s soundcard. Having downloaded and installed a copy of Argo (see QRSS Resources for more information) it is now only a matter of tuning in your receiver and watching the computer’s display.

Many, who take this route, will also include some form of isolation between the computer and the receiver by the use of a dedicated interface. Others will take the homebrew route and create a bespoke solution.

What you need to transmit QRSS

It is unlikely that any commercial transmitter will be capable of transmitting a QRSS signal. For a quick solution, consider buying one of the many low power (QRP) kits that are currently available. A list of the more common and easily converted kits may be found elsewhere on this blog. They are not expensive and, in most cases, very easy to assemble.

Next, you will need some means of keying the transmitter. The method chosen by many is a pre-programmed integrated circuit such as the Atmel ATtiny, the AVR, PIC, or perhaps the PICAXE. If you are not an aficionado of this particular type of technology, then help is at hand in the form of commercially available units which come pre-programmed. Once again, I have done my best to include details of what is available in the ‘Resources’ section of this blog.

The primary design consideration for a QRSS transmitter is, without doubt, stability. Given that we are transmitting a tiny signal within a very narrow band of frequencies, it is of the utmost importance that our signal does not drift. If you are not fortunate enough to possess a digitally synthesised VFO, then the chances are that you will opt for crystal control. A crystal heater will also aid stability, as will putting the finished article in an insulated box.

Making the most of QRSS

One of the things that I have found since getting involved with the QRSS mode is that it makes you far more aware of basics of amateur radio. I have spent a great deal of time making sure that my aerial system is as efficient as I can possibly make it. I have also gone to great lengths to ensure that the output from the transmitter is matched as closely to the aerial as it can be.

Many of us involved in QRSS have a web site onto which we upload images of our captured signals. Mine, for example, takes a ‘snapshot’ of the Argo output once every minute and then makes it available for viewing on the web (www.g4cwx.com). Apart from the fact that I can monitor my station remotely, it gives other amateurs the opportunity to see if their signals have reached my receiver. Several amateurs have also taken this one step further by creating web pages which act as compendiums, or aggregators of individual signal grabbers. Thus, you can see on a single page, how many grabbers are receiving your signal.

As part of the process of getting ready to receive and transmit QRSS signals, I first turned to WSPR (Weak Signal Propagation Reporting). A detailed explanation of how it works is outside the scope of this short piece, but suffice it to say that it is an excellent way to determine how effective your existing station is at transmitting and receiving low power communications from around the world. Joe Taylor’s web site at: http://physics.princeton.edu/pulsar/K1JT/ is a good place to learn more. One very positive advantage of trying WSPR is that most stations with a standard HF transceiver hooked up to a computer can be on the air in next to no time at all.

QRSS Resources

The following list of resources is by no means comprehensive, but it will provide a good starting point for anyone interested in giving QRSS a sporting chance. I am more than happy to add to this list if anyone can come up with some useful additions.

Transmitter kits

I can do no better than direct you to another part of this blog which carries a comprehensive list of the available kits which may well be suitable for use as low power QRSS transmitters.

http://knightsqrss.blogspot.com/2010/01/qrss-able-kits.html

Crystals

There are probably a lot more suppliers out there, but for me this is the first place that I look for those elusive frequencies, such as 10.140. I also have to add that their prices are very reasonable indeed – especially if you order in bulk and their delivery times are usually very fast.

http://www.expandedspectrumsystems.com/prod4.html

Programmed IC keyers

The two most popular commercial products are:

http://www.proehl-elektronik.de/cwk/cwk_e.html
http://k1el.tripod.com/index.html

Web sites

http://www.qrss.thersgb.net/
http://mail.cnts.be/mailman/listinfo/knightsqrss_cnts.be
http://on5ex.be/clipboard_view_unreg.php
http://www.hanssummers.com/

Compendiums and aggregators

http://digilander.libero.it/i2ndt/grabber/grabber-compendium.htm
http://www.ik0vve.net/mept6.aspx

Software

http://physics.princeton.edu/pulsar/K1JT/
http://digilander.libero.it/i2phd/argo/index.html
http://digilander.libero.it/i2phd/spectran.html
http://freenet-homepage.de/dl4yhf/spectra1.html

Rock-Mite mod - basic principal

2010-01-19T04:31:00.000-08:00

The trick with the Rock-Mite is the PIC (programmable interface controller) which provides keying, RIT and other functions. It is a 12C508 which is pin-compatible to the 12F629 and in a way also to the PICAXE-08M. The main modification would be to write a new firmware for the controller, hence the MEPT/RX would have an onboard beacon keyer.

Check out the schematics:

The Rock-Mite uses a simple oscillator (Q4,Y2) which is pulled (D6) for RIT. Some options here:

replace the varicap diode by a rectifier or LED and FSK the oscillator with Q1
leave the RIT alone (allowing for beat offset) and add keying voltage from GP2 (pin 5, PWM!) via some low-pass filter and resistors
reroute Q2 to GP0 and add extra crystal pulling using GP2's pseudo DAC (PWM)

I will probably go for option 3.

The receiver will remain nearly untouched, it already employs a crystal filter and all things needed for grabbing. C1 and C2 however should be replaced by trimmers, so that the filter can be tuned.

SW PSK-20 mod - basic principal

2010-01-19T00:49:00.000-08:00

Replace the 5.0688MHz crystal by a 5.000Mhz one. That gets you to 14000.800kHz.
Bonus here, there only is one crystal to "replace", which calls for a switchable design to keep the PSK-20 original functionality.
Non-QRSS mod: drop in a 5.200MHz xtal...

Ten-Tec 1340 mod - basic principal

2010-01-19T00:45:00.000-08:00

Don't build the VFO but a 4MHz XO instead, include slight pull and mod. That is all that needs to be done for 7000.800kHz.
For 7059.900kHz, replace all 11MHz crystals by 11.0592MHz xtals.

Additionally, one could consider to change the keying, since for TX, the the transmit mixer (with TX LO) is switched on/off. Some risk of chirp involved here. When using FSK, don't bother!

QRSS-able kits

2010-01-18T05:51:00.000-08:00

It is believed that the following kits can be easily modified for QRSS operation (in no particular order):

Hans Summers QRSS TX ( 12V mod )

This is by far not complete yet, please add, or tell one of the blog's authors, if you are aware of other kits!

WM-2 LED mod

2010-01-17T16:50:00.000-08:00

Most QRPp shacks no doubt have a WM-2 power meter.
I run my WM-2 on batteries for portability around the shack but I had a habit of forgetting to switch it off. Even with a rechargable battery it was annoying.

Solution was to fit a high brightness LED.

Simple but effective!

Colin

The GenesisRadio Q5 QRSS modification. Updated

2010-01-17T01:29:00.000-08:00

Here is the current state of my modified Q5. It is very usable as a QRSS Beacon running FSKCW or QRSS (on/off keying) modes. Tested on 80/40/30m.
I have also now done a KISS mod to eliminate the very slight chirp when it was used for the QRSS keying mode.

To improve the QRSS keying just add a 330r in series with the emitter of T1 (BC556) on the Q5, this will soften the keying of the Oscillator. More details in the Updated circuit.

Colin

QRSS Frequencies

2010-01-16T07:11:00.000-08:00

Alternate choices where thought up so that all licence groups (not

extra class??) could also transmit QRSS. IE up from the bottom of the band(s) which is a limitation in some Countrys.

Current status/plan:

* 137.6 - 137.8 kHz
* 1.8432 - OK
* 3.500, 3.575, 3.579 - OK, 3.5999 - OK
* 7.000, 7.0402 - OK, 7.0599 - OK
* 10.140 - OK
* 14.000, 14.0989 - OK 14.31818 (not tested)
* 18.1089 OK
* 21.000, 21.1489 (not tested)
* 24.9289 (not tested)
* 28.000, 28.188, 28.322 (not tested)
* 50.294,400-600 (WSPR section) OK

3599/3579 and 7059/140989 where amongst some tests made and good results where obtained.

Nick VK1AA (GenesisRadio) has a number of the common Xtals available which can be found on the GenesisRadio order page.

Joachim PA1GSJ has also come up with some great ideas to get to these new frequencies for those not using DDS.

KnightsQRSS Blog - 500KHz

2010-01-16T04:39:00.000-08:00

What a good idea, a one stop shop for information exchange, circuits etc.

Fancy taking a look at 500KHz ?

RX
In my experience some very good results can be obtained with just the HF antenna. Take out all ATU's internal or external, they will attenuate the 500KHz. If you like what you hear, wind a coil on a Ferrite Rod, try 50 Turns and parallel tune with a 500 pF Variable Capacitor. Use a 5 turn link winding to the RX.

My signal 130uW ERP getting into M0LMH at 194Km.

TX
There are numerous circuits around not many for QRPp so I went it alone. I have used 2 methods to obtain 500KHz.
1)Two Xtals on an XOR chip selecting the difference.
2)A 4MHz range Xtal divided by 8 in a binary divider. When you look on the web, yeh yeh, its been done before.

PA
500KHz enthusiasts mostly run big Mosfets, lots of I, big heat sinks and set their sheds on fire. Not the scene for Knights.
I came straight out to an LPF from a few parallel gates on my buffer chip initially. I am now using a good old second hand BFY50 and a complementary PNP device from the junk box, BC303 I think, in a Class D push pull circuit.
I am also experimenting with IC's in push pull and getting nice results.

Class D BFY50/BC303 PA

TX Antenna
Now you need to read up a little, the bit of wire for RX just won't get you far. My antenna is smaller than most others and cramped, 14m of wire, yet carefully tuned amd matched it works.

KnightsQRSS blog

2010-01-16T04:06:00.000-08:00

Having experienced that the same questions keep being asked, it may be a good idea to have a common place to lay down information.
Want to become an author? Drop me a note... This is intended to be a shared blog.

73, Joachim pa1gsj