Using the second intermediate frequency, often at 455kHz, is widely known. A suitable I/Q-SDR would be based on a 1.8432MHz (canned) oscillator, resulting in a 460.8kHz center frequency. Assuming a 24k sample rate, would be adequate to cover the range from 450 to 460kHz perfectly.
Many I/Q-SDR kist are available, due to the size and the low price, the softrock lite could be suitable best.
So, why the ATS-404. I was looking for a relatively cheap wide coverage receiver having direct frequency entry. The 5kHz tuning steps on shortwave suit the 10kHz wide SDR just fine.
The ATS-404 uses the TA8132AN AM/FM-receiver IC. This IC has go the advantage of providing an IF-out at pin 9 (see data-sheet). Slight downside: the TA8132 employs a 450kHz intermediate frequency...
A service manual for the ATS-404 can be found here:
http://www.thiecom.de/ftp/sangean/ats404/
The remaining question... where to put the I/Q-SDR? Using a softrock lite, one may consider using the battery compartment. Speaking of battery, the radio runs of 4 AA cells. It can also be operated from 6V external power. I wonder if 5V from a USB-port would be sufficient, finally, the idea is to use a computer for the SDR anyway.
Which brings me to the last idea... a cheap (stereo!) USB-sound-interface could also be accomodated in the battery compartment, so that only connection would be a USB cable to the computer.
Saturday, August 6, 2011
Monday, August 1, 2011
Sunday, July 17, 2011
BB6W / BB7V clones for QRSS
If you browse the wide of the internet on the hunt of information about Diamond's BB6W or BB7V, you will most likely come across some images and blogs. One of the most helpful blogs, in my view, is Martin's ECLECTIC AETHER. The link points to the actual article....
As to images, for me, the image found here: http://www.cqcqde.com/shop/88_108.html is most informative.
Referring to Martin's blog, it seems that the "matching" device actually is a 6:1 UnUn ferrit toroid transformer with a 600Ohm (120W) termination resistor. The aerial being rated 250W, this means that up to 50% or 3dB of power is burnt in said resistor. The bandwidth of the aerials is mentioned to be 2Mhz to 30MHz.
Martin mentions the inferior performance of the 6:1 UnUn the why it was wound in the original BB6W. To my believe there is actually some thought in this. Japan, that where the aerial comes from, is a very noisy, QRM that is, country. Hence, Diamond seems to have decided to compromise power coupling versus common mode noise by reducing the capacitive coupling between the windings.
My interpretation of this aerial comes close to a short end-fed random wire, which is broadened by a sort of termination known from aerials like the T2FD, with a twist however.
Here is what I believe is interesting about the concept. Usually end-fed random wires are used in combination with 9:1 UnUn transformers, which result in a feed point impedances of 450Ohms. The BB6W matching unit however transforms to 300Ohms only, where the termination is twice that. Obviously, one does not want 300Ohms of termination, that would just form a dummy load...
So, what we got here is a short broadband aerial, horizontal or vertical in which half the power is absorbed.
In QRO, the tricky bit is the non-inductive resistor. It is doable, and certainly to a lower price than Diamond sells the aerials.
In QRSS, which essentially is QRPP, we are not troubled by the problem mentioned above. In fact, we could use a regular 1/4W carbon resistor and still we would be fine.
Two things came to my mind
It would also not be too difficult to build a termination resistor being good for 10W or so....
Last thing, what way of winding the UnUn would be most appropriate? You decide... Diamond's way would provide you with less RX-QRM, Martin's method would pass more TX-power to the wire.
As to images, for me, the image found here: http://www.cqcqde.com/shop/88_108.html is most informative.
Referring to Martin's blog, it seems that the "matching" device actually is a 6:1 UnUn ferrit toroid transformer with a 600Ohm (120W) termination resistor. The aerial being rated 250W, this means that up to 50% or 3dB of power is burnt in said resistor. The bandwidth of the aerials is mentioned to be 2Mhz to 30MHz.
Martin mentions the inferior performance of the 6:1 UnUn the why it was wound in the original BB6W. To my believe there is actually some thought in this. Japan, that where the aerial comes from, is a very noisy, QRM that is, country. Hence, Diamond seems to have decided to compromise power coupling versus common mode noise by reducing the capacitive coupling between the windings.
My interpretation of this aerial comes close to a short end-fed random wire, which is broadened by a sort of termination known from aerials like the T2FD, with a twist however.
Here is what I believe is interesting about the concept. Usually end-fed random wires are used in combination with 9:1 UnUn transformers, which result in a feed point impedances of 450Ohms. The BB6W matching unit however transforms to 300Ohms only, where the termination is twice that. Obviously, one does not want 300Ohms of termination, that would just form a dummy load...
So, what we got here is a short broadband aerial, horizontal or vertical in which half the power is absorbed.
In QRO, the tricky bit is the non-inductive resistor. It is doable, and certainly to a lower price than Diamond sells the aerials.
In QRSS, which essentially is QRPP, we are not troubled by the problem mentioned above. In fact, we could use a regular 1/4W carbon resistor and still we would be fine.
Two things came to my mind
- use a 9:1 UnUn with a 900Ohms resistor
- use an air-core (auto-) transformer
It would also not be too difficult to build a termination resistor being good for 10W or so....
Last thing, what way of winding the UnUn would be most appropriate? You decide... Diamond's way would provide you with less RX-QRM, Martin's method would pass more TX-power to the wire.
Saturday, June 11, 2011
XPware was made freeware!
XPware is freeware now! It runs under WinXP (have not tested any other win-flavor).
http://www.glaswerks.com/xpwar
It can talk to the following controllers (test myself):
I did those tests on the grabber pc, which in parallel was running one instance of winamp, two instances of spectrum and argoupload. Since modern PCs are not equipped with serial ports anymore, USB2Serial cables were used. All in all I believe being fine to going on with NBDP acitivities.
NBDP what's that? You may ask... This is the modern name for the mode family FEC, SelFEC and TOR. The acronym stand for Narrow Band Direct Printing.
PS: if you are on facebook, feel free to join the recently created group "Teleprinting Over Radio"
http://www.glaswerks.com/xpwar
It can talk to the following controllers (test myself):
I did those tests on the grabber pc, which in parallel was running one instance of winamp, two instances of spectrum and argoupload. Since modern PCs are not equipped with serial ports anymore, USB2Serial cables were used. All in all I believe being fine to going on with NBDP acitivities.
NBDP what's that? You may ask... This is the modern name for the mode family FEC, SelFEC and TOR. The acronym stand for Narrow Band Direct Printing.
PS: if you are on facebook, feel free to join the recently created group "Teleprinting Over Radio"
Tuesday, June 7, 2011
Teleprinting Over Radio Revival?
Guys, I was wondering if it would be possible to revive a mode that seems to be lost, TOR (AmTOR or if you want - or NBDP as it is called today). To it's time, AmTOR was kinda expensive/hard to get qrv on easily. Transceivers needed a certain RX-TX switch over timing, modems were not cheap, software hard to get hold of. I remember, to the time I had some AmTOR software running on my trusted Apple II.... but that is a long time ago.
In that time, multi-mode controllers came on the market, worth more than a short-wave transceiver... so, I could not afford any of those. Even worse, the transceiver I could afford was a second hand Drake TR4, which would never have had a single chance to meet the timing demands of AmTOR. Hence, I was stuck to my trusty combination of the TR4 and a Siemens T100 doing Radio TeleTYping (aka RTTY).
Oh... and those ARQ signals where present everywhere!
Today, TOR (AmTOR for good measures) is relatively dead. Although, hardware is cheaply available today, and there is also some software downloadable, emulating the hardware solutions. Today's transceivers don't need to be modified anymore, to achieve the timing required for ARQ. AmTOR is a robust mode, good for some straight keyboard communication.... I wonder if we could revive this mode for amateur radio.
Mind you, this mode TOR (Teleprinting Over Radio) is still in use in GMDSS. Actually, it still is the preferred mode in today's maritime communication. Actually, for my GMDSS GOC, I lately had to learn how to connect to a Telex land-line.
Folks, would it not be cool to give this AmTOR a second life? In particular since second hand hardware is available as cheaply as presently....
PS: if you are on facebook, feel free to join the recently created group "Teleprinting Over Radio"
In that time, multi-mode controllers came on the market, worth more than a short-wave transceiver... so, I could not afford any of those. Even worse, the transceiver I could afford was a second hand Drake TR4, which would never have had a single chance to meet the timing demands of AmTOR. Hence, I was stuck to my trusty combination of the TR4 and a Siemens T100 doing Radio TeleTYping (aka RTTY).
Oh... and those ARQ signals where present everywhere!
Today, TOR (AmTOR for good measures) is relatively dead. Although, hardware is cheaply available today, and there is also some software downloadable, emulating the hardware solutions. Today's transceivers don't need to be modified anymore, to achieve the timing required for ARQ. AmTOR is a robust mode, good for some straight keyboard communication.... I wonder if we could revive this mode for amateur radio.
Mind you, this mode TOR (Teleprinting Over Radio) is still in use in GMDSS. Actually, it still is the preferred mode in today's maritime communication. Actually, for my GMDSS GOC, I lately had to learn how to connect to a Telex land-line.
Folks, would it not be cool to give this AmTOR a second life? In particular since second hand hardware is available as cheaply as presently....
PS: if you are on facebook, feel free to join the recently created group "Teleprinting Over Radio"
Friday, May 27, 2011
SWL PSK-20 for JT65 & WSPR
PSK31 is fun, agreed, however, would there be an additional option for using the PSK-20 transceiver for other weak signal modes? The question is, would it be possible to modify the PSK-20 such that instead of operating in LSB on 14.071MHz, it would also be operating USB on 14.0775MHz (corresponding to a "dial frequency" of 14.076MHz)?
Lets have a look at the PSK-20's design. We are dealing with a 9.000MHz i.f., with a 9.002MHz b.f.o. obviously. The l.o. operates at 5.070MHz. Both oscillators use crystals, a pulled up 9MHz one and a pulled up 5.0688MHz one.
Looking what could be done for the LSB to USB modification, I figure the 9MHz xtal could either pulled down by means of inductors, "penned" down or it can be replaced with another one.
Replacement would be provided by two different options. Since 9MHz is a very popular i.f., side-band crystals are available for not too much money. The second option possibly already sits waiting in the junk-box somewhere. The CB channel 3 transmit (overtone) crystal has got a nominal frequency of 26.985MHz. On the fundamental that would result in a 8.995MHz beat frequency. Still somewhat too low.... but.... in the original design, the 9MHz crystal is pulled up, remember? The CB crystal would therefore fit perfectly! Lets just assume the b.f.o. would be at 8.9985MHz.
Penning the crystal in place down, I would do "in situ". That way, everything will be set when the desired frequency is reached and only the crystal's housing would have to be soldered in place again.
Now lets have a look at the local oscillator. The JT65 centre frequency is 14.0775MHz. With an i.f. of 9.000MHz, this would be reached by a l.o. at 5.0775MHz obviously. Equally you could add up the b.f.o. and l.o. frequencies to end up at the "dial frequency". 5.0775MHz looks a an ambitious 8.7kHz up-wards pull for a 5.0688MHz crystal, and most likely it will be in the existing discrete oscillator.
However, all is not lost. Seen that 2x5.0775 results in 10.155, there would be a couple of great options for (pulled!) digital gate oscillators and Flip-Flop dividers, namely CB synthesizer crystals.
Alternatively, the 10.160MHz xtal could be "penned" down to 10.155MHz; equally, a 10.150MHz xtal could be penned down to 10.142MHz to allow for the 20m PSK31 frequency.
In this way, I hope I can create a decent dual frequency narrow-band data transceiver.
Lets have a look at the PSK-20's design. We are dealing with a 9.000MHz i.f., with a 9.002MHz b.f.o. obviously. The l.o. operates at 5.070MHz. Both oscillators use crystals, a pulled up 9MHz one and a pulled up 5.0688MHz one.
Looking what could be done for the LSB to USB modification, I figure the 9MHz xtal could either pulled down by means of inductors, "penned" down or it can be replaced with another one.
Replacement would be provided by two different options. Since 9MHz is a very popular i.f., side-band crystals are available for not too much money. The second option possibly already sits waiting in the junk-box somewhere. The CB channel 3 transmit (overtone) crystal has got a nominal frequency of 26.985MHz. On the fundamental that would result in a 8.995MHz beat frequency. Still somewhat too low.... but.... in the original design, the 9MHz crystal is pulled up, remember? The CB crystal would therefore fit perfectly! Lets just assume the b.f.o. would be at 8.9985MHz.
Penning the crystal in place down, I would do "in situ". That way, everything will be set when the desired frequency is reached and only the crystal's housing would have to be soldered in place again.
Now lets have a look at the local oscillator. The JT65 centre frequency is 14.0775MHz. With an i.f. of 9.000MHz, this would be reached by a l.o. at 5.0775MHz obviously. Equally you could add up the b.f.o. and l.o. frequencies to end up at the "dial frequency". 5.0775MHz looks a an ambitious 8.7kHz up-wards pull for a 5.0688MHz crystal, and most likely it will be in the existing discrete oscillator.
However, all is not lost. Seen that 2x5.0775 results in 10.155, there would be a couple of great options for (pulled!) digital gate oscillators and Flip-Flop dividers, namely CB synthesizer crystals.
- 10.160 / 2 = 5.080 for JT65a: 5kHz downwards pull on 10MHz
- 10.140 / 2 = 5.070 for PSK31: 2kHz upwards pull on 10MHz
Alternatively, the 10.160MHz xtal could be "penned" down to 10.155MHz; equally, a 10.150MHz xtal could be penned down to 10.142MHz to allow for the 20m PSK31 frequency.
In this way, I hope I can create a decent dual frequency narrow-band data transceiver.
Tuesday, May 24, 2011
Look What I Found!
A local hardware store offered those:
F Type Connector to Bayonet Nay Connector adaptor. Those essentially conclude my usage of overpriced 50Ohms stuff for QRP applications.
Well, the adaptors did not came cheap, they are €2.40/pc, but I feel they are totally worth it.
 | |
| F2BNC |
F Type Connector to Bayonet Nay Connector adaptor. Those essentially conclude my usage of overpriced 50Ohms stuff for QRP applications.
Well, the adaptors did not came cheap, they are €2.40/pc, but I feel they are totally worth it.
Monday, May 23, 2011
QRSS Studies - the Results
Seen that there is no more for me to investigate in QRSS, other radio topics will soon become more relevant to me, and also to this blog.
The results I can report on QRSS
Conclusion I learned from my experiments, on-air and off-air
What I miss in QRSS is interaction, consequently, I will for the time being cease QRSS activity until further notice.
My focus for the time to come will be on data modes such as PSK500, ALE, etc.
Another thing that crossed my mind occasionally, going QRO with some homebrew kit. Saying QRO, I mean QRO, i.e. legal limit. It is not so much the urge of being heard, it's more the design challenge here.
The results I can report on QRSS
- You can operate a decent visual grabber in very densely populated regions. One will see the neighbours' TV sets, which in many cases is not more than just annoying.
- The reception of WSPR is not affected by urban noise, low profile and even indoor antennas give good results.
- There is no need to occupy your expensive main rig or a professional receiver, a cheap and cheerful home fixed frequency RX does the jobs.
- Setting up an online grabber is something that anyone with internet access can do, no excuses here. The demands on the respective computer are minimal. An Intel ATOM can easily operate two grabbers and WSPR (rx in my case), have a third instance of speclab running, be a print and file server and operate winamp for internet radio... all at once.
Conclusion I learned from my experiments, on-air and off-air
- There are many more transmitting stations than receiving ones.
- Despite my efforts to motivate the installation of additional grabbers, there are still only a few.
- Operating a grabber blocks other activities, at least on the bands the grabbers are active on.
What I miss in QRSS is interaction, consequently, I will for the time being cease QRSS activity until further notice.
My focus for the time to come will be on data modes such as PSK500, ALE, etc.
Another thing that crossed my mind occasionally, going QRO with some homebrew kit. Saying QRO, I mean QRO, i.e. legal limit. It is not so much the urge of being heard, it's more the design challenge here.
Thursday, May 19, 2011
Froyo & Market on the A7ht
Someone hacked it, the Archos 7 home tablet. What a pleasure to see froyo and google market running on the gadget. At times it seems to struggle during bootup, this could be due to the lack of cell-network hardware.
With expanded options of market, the cheap tablet is really useful to me now. Let ne give you an example, there are apps out there for watching webcams... perfect to keep an eye on one or more grabbers...
Froyo is not slowing down the device, this was the first thing I feared. What like about froyo in particular, the orientation of the plain desktop changes with rotation of the device. Occasionally is comes really handy.
Now looking for some interesting ham-radio apps...
Monday, May 16, 2011
The Ultimate Icom IC-M700D+
OK, this may sound a little unfair and overdone... today I managed to secure an Icom IC-M700 purchase. That means, I will create the ultimate IC-M700(whatever)+++.
Here is the idea: All of the IC-M700xx brought their individual pros and cons. The aim is to create the ultimate transceiver based on whatever Icom had to offer in the M700 series.
I believe, I have found it!
Basis:
However, since it is very hard to get your hands on one of those, merging the IC-M700D(or F) with an IC-M700, will get you at least half the way to an IC-700TY.
73!
Here is the idea: All of the IC-M700xx brought their individual pros and cons. The aim is to create the ultimate transceiver based on whatever Icom had to offer in the M700 series.
I believe, I have found it!
Basis:
- IC-M700D: three power regimes, USB only (limited TX-QRGs, see mod)
- IC-M700: USB/LSB, TCXO, one power regime only
- the modified IC-M700D will be equiped with the RF-unit of the IC-M700 and hence providing USB and LSB voice operations at three different power levels, which to me sounds like a nice rag chew transceiver.
- the IC-M700 seems to be crippled by the use of the USB-only RF unit of the IC-M700D. However, the base band stability of the TCXO makes the USB-only unit a perfect transceiver for digital modes.
However, since it is very hard to get your hands on one of those, merging the IC-M700D(or F) with an IC-M700, will get you at least half the way to an IC-700TY.
73!
Subscribe to:
Posts (Atom)