Saturday, April 14, 2018

First Week/Weekend With The uBITX

My time around the house is rather limited.  I work from 10-7, Sunday through Thursday.  When I wake in the morning, I have approximately 3 1/2 hours to get ready, have several cups of coffee, and play radio.  When I get home after a day of climbing telephone poles and dealing with customers' filthy houses and inane issues with their cable, I sometimes don't have the patience to get into a QSO or two.  Although I completed my uBITX last weekend, I didn't really get a chance to put it through a good workout until 4/13 and 4/14.

So far, there are a few annoying quirks that the uBITX has...namely, the CW offset.  If I set the rig to 7.040.000 and send a few CQs, the Reverse Beacon Network will receive it at 7.040.600.  Sure, I get it...but it's still a nuisance, since I have to remember to adjust for offset manually sometimes.  Since Ian Lee's software has RIT built into it, I can set the rig to the station's frequency and adjust for the offset myself.  It's quite elegant, in that the RIT isn't limited to just a kilohertz or two...if a DX station is working split, I can use the unlimited RIT to create the split on the fly.  And it works VERY WELL.

Also, the Raduino when switching from SSB to CW clips the first dit or two.  This makes for choppy sounding keying initially.  Once it has kicked over, it's fine, but it's far from perfect. 

The uBITX on 60 Meters

Last night, I snagged W1MGY, the Titanic Marconi Memorial Radio Association of Cape Cod's 106th anniversary of the sinking of the Titanic.  MGY was the callsign of the wireless station onboard the Titanic.  I have been wanting to work this Special Event for years, and last night I nailed it on 7.038 MHz with one call.  And just today, I have worked a few Parks on the Air stations via CW.  

Next thing to do is to improve the microphone and the power supply.  

Friday, April 13, 2018

My Latest Rig...the uBITX


On February 6th, I placed an order on hfsignals.com for a radio that is quite literally standing conventional wisdom about Amateur Radio onto its head: the Indian-made, multiband, SSB/CW uBITX transceiver.

Ashar Farhan, along with Dan Tayloe, Arv Evans, and Jim Kortge, designed and developed the ORIGINAL BITX40/20 radios more than 11 years ago.  The older units are significantly different from the newer versions made in India...namely, with the addition of more band coverage, more crystal filtering, and most importantly, rather than polyvaricon tuning, an Arduino clone handles the tuning.  In fact, calling this radio a software defined radio is accurate.

During the approximately 2 months for the radio to arrive, I ordered a printed case for the rig from Dave Schmidt at Wolfland Computers and Hobby (wolfland.net).  Dave prints the cases in several styles and SEVERAL color combinations...he even prints your call on the front of the box, if desired.

Last week it arrived.  And I couldn't wait to begin the assembly process.

These radios are already hand assembled by Ashar's team in Hyderabad, India, but what YOU...or I as the case was, had/have to do is the final mounting in a box, and then add connectors and controls.

If you purchase a box that already has cut-outs for the Raduino screen and the potentiomer and encoder, and power and RF on the rear, the assembly goes MUCH faster.  I already had the box on hand, so the assembly time was literally trimmed by hours, if not days.

The 3.5mm jacks sent with the radio are, in all honesty, TERRIBLE.  They are the style that is meant for direct mounting to a circuit board.  If you have experience soldering, this is a minor inconvenience, but I can see this being a problem for someone with less experience.  Basically, the pins to solder the wires from the audio and Raduino connectors are REALLY small.  If you have a decent junkbox, substituting a STANDARD jack, as I did for the CW key jack, is OK.

The first problem encountered in the instructions of hfsignals.com, was that the CW jack directions are wrong.  Referring to ubitx.net solved any of these minor hiccups.  One thing I did to make assembly a bit easier for myself, was to set the jack for straight keying.  There are a couple of reasons for this...mainly simplicity, as it's only 2 wires necessary...and...that I prefer external keyers such as my 43-year old TenTec KR5 single-lever paddle.

After setting it up and doing some initial testing, there is a SIGNIFICANT glitch in the software that comes installed onto the Raduino: CW keying is sporadic and pretty poor.  Ian Lee, KD8CEC's EXCELLENT software is the "fix du jour".  Not only does Ian's software correct the CW glitch, it adds 160m to the rig, adds full CAT control (and WSJT-x can be used natively), adds RIT, adds IF Shift, adds Dual VFO, adds memories, and adds the ability to use a Memory Manager...all software that he himself writes.  My rig has version 1.06 on it, but 1.07 is out at the time this is being written.  Simply put, it's NECESSARY software to make the uBITX into a radio that can compete with the Big Three's entry level rigs. Ian Lee's software can be found on his website: http://www.hamskey.com/2018/02/cat-support-ubitx-firmware-cec-version.html

As I am writing this, I have already checked into the Hit and Bounce Slow CW Traffic net on 7112, ECARS on 7255, and listened to WWV on 10 MHz.

The instructions for setting up the receive are easy, but you will need another radio to make it simple.  Aligning the RX with WWV or with a laptop that has digital software on it so that you can utilize an FT8 stream compared to another rig is how I did it.  It's a tad confusing, but, persistence pays off.

My particular radio had an issue where my sidebands were reversed, but, after reading Ian Lee's blog about how to overcome this, made it simple.  You literally have to change the clock frequency of the Raduino to correlate with correct sounding audio.  Again, having another rig nearby helps, and is almost required.

The Raduino is a clone...a VERY cheap clone.  One MAJOR problem developed with mine, in that, I can no longer connect to the PC for setting up memories, or adjustments. Luckily, EVERYTHING can be done via the Calibration menu...so I'm not too worried.  I have a back-up of this configuration...so I'm not too upset about the glitch.  If it REALLY bothers me, I'll simply purchase another uBITX for parts.  It's a little disappointing, since I wanted to use this rig with the digital modes.

Ashar included a small PTT switch and a small electret microphone element, so that a BASIC microphone with push-to-talk can be built.  My mic is a lash-up that I soldered together before work this week...it sounds a bit distorted, so for now until I can build/buy/steal a suitable replacement, I have been doing 100% CW.  The 10-12 watts really gives the uBITX a HUGE advantage over my FT-817ND (double the power on the low bands).


For $109 + $10 for DHL Shipping from India, along with a $30 case from Wolfland, it's a HELL of a bargain.  There is NOWHERE else on the PLANET that you can buy a radio that's NOT Chinese (these are assembled by women in India, which I think is tremendously cool...women have a FAR BETTER attention to detail than men do!), has the ability to be loaded with FREE software, gives you 160-10, including 60m (with version 1.06) at 12W from 160-40, and 3-6W from 30-10. The last time I paid around $100 for a transceiver, I bought an MFJ Cub, which was an utter disappointment to say the least.

For just under $150 for EVERYTHING, I have a basic rig that is cheap enough to be almost disposable, but has enough features to be usable.


Friday, March 30, 2018

It Arrived!



On Tuesday, March 27th, it just so happened that I was sitting in the street in my Spectrum Cable van, when the UPS guy came around the corner.  After intercepting him, and running inside with the box from Tennessee, I ran downstairs into the subterranean shack here at the home QTH.

After cutting through the multiple layers of bubble wrap and tape (the last owner had it professionally packed at The UPS Store), my "new" HW-7 was sitting on my desk.

Initial Impressions

The first thing that jumped out at me was the smell, the brown hue, and the stickiness that screamed SMOKER at me.  Normally, this is a point of contention for many, as it should be when purchasing an antique ANYTHING...but this rig was free.  A little (no...a LOT!!!) of TLC, some Simple Green, and a gentle brush made the panels (disassembled from the chassis, of course) squeaky clean...and without ruining the lettering on the faceplate.

Next...while the radio was disassembled down to the chassis, I took about an hour and examined it for obvious modifications.  Thankfully, there are FEW.  One such mod was the replacement of the original power socket with one that appears to be from an HW-9.  The original owner is an HW-9 enthusiast, so this isn't too much of a surprise.  Next, on the power leads, a small value capacitor was soldered across the red and black.  This, I believe, was added to handle voltage spikes...or at least that's what I have read elsewhere. 

Further, a transistor socket was added to where the 40673 is placed.  There must have been a reason for this...experimentation, perhaps. 

I reassembled the cabinet with the exception of the top panel, just so I could observe the innards while I am getting acquainted with the antique rig...and just as the last owner said...it turned on, but didn't do much.  So, I started with the obvious...how's the audio?  Similar...no...IDENTICAL to other HW-7s I have owned, the quite pronounced microphonics of the CA3035VI  were present.  When the preselector is peaked, merely touching the knobs or cabinet makes the sound of tapping a microphone in the headphones.  So...the ancient audio amplifier still works.

But what about that FET socket?  Turns out that the original 40673 had been replaced with an "equivalent" device, but there was no life coming out of it.  Since it was in a socket, I didn't bother with any test procedures...I popped it out, and inserted a BRAND NEW 40673 that had been given to me by my best friend, Keith WB2VUO.

A few turns of the VFO capacitor, and the old rig burst to life.  LITERALLY.  Just as I remembered from my last HW-7, 40m in the early evening was filled with stations, W1AW as well.  This let me know that the dial calibration was CLOSE.  It's no service monitor, but it's not bad. I listened to the CW bulletin and was pretty satisfied with the apparent lack of drift once the RX had warned up sufficiently.

Now the moment of truth: did the transmitter work?  At just about 2.2 watts output on 40, the rig seemed to be in decent health, considering it had been in the shack of a smoker...AND...is as old as I am.

But once the relay clicked back over into receive, the audio was gone.  Since the lid was already off, I touched the RX contacts with a micro screwdriver to bridge the gap, as it were.  Sure enough, that sticky nicotine residue had found its way inside the rig, and gummed up the contacts.  A few gentle passes with some thin, fine grit sandpaper cleaned the contacts up enough to make it operate as it used to.

Going Forward

Well...it's absolutely every bit of HW-7...complete with the lack of RX offset on 40m.  The Heath engineers designed this radio with a glaring defect.  There have been numerous articles and designs for adding RIT to the front end, but, I have NEVER been a fan of mods, especially in the HW-7/HW-8 rigs.  Sure, they make it more usable, but being a purist, this is a non-starter for me.  This radio is a toy.  It is a shack accessory.  It is a modest plaything...and it's also not my only radio, as the last one was post-divorce in 2013.  So, the way around this for ME is to use the feature that attracted me to this radio when I was a Novice 30 years ago: the crystal transmit feature.  Back in the 1970's, Novices were restricted to Crystal control.  It was thought that the Novice needed operating experience, and dealing with a drifty VFO wasn't part of the FCC's plan.  KC9ON sells FT-243 STYLE crystals.  By STYLE, I mean that these are old school crystal cases with small form factor HC-49 rocks soldered inside.  This will allow me to transmit on 7030...or 7055...or 7112...mainly SKCC Group frequencies, and perhaps a QRP calling frequency.  With xtal control, I can use the RX and tune for signal.  Sure, it's primitive, but I don't mind...it's a blast just using this old rig.

The transmit on 20 is ghastly.  Tons of the classic "whoop-whoop-whoop" keying action.  I suspect that the oscillator is a tad too sluggish at this point...perhaps some component replacement is in order...maybe a realignment.  I'm not in any particular hurry to make it happen.

Well...the Reverse Beacon Network hears when I transmit, and the receiver is operating fairly well, for what it is.  So that's 90% of the battle.  She just needs some refinement...and some more cleaning...and new caps...and maybe some updated transistors in the TX section...

She's a time machine. 

Monday, March 26, 2018

My Upcoming Project...ANOTHER HW-7

(A 1972 Heathkit HW-7 QRP transceiver...the funny part about this particular photo is that I took this picture in my ex-wife's backyard in 2013.  This is THE HW-7 that she bought for me after our divorce.  That's HER patio table!!  This photo has been circulated world-wide, too)

Last week, on the Facebook QRP group, a gentleman asked if anyone was selling any Heathkit HW-8s.  Not having EVER been a fan of the 8, I tail-ended that thread and asked if anyone had a 7 that they were selling.

I received a PM from a ham in the northeast that said he had one that I could HAVE, and I only had to pay for shipping.

How amazing!!

One caveat from this generous man: "It turns on, and does little else."

It is coming with the matching HWA-7-1 power supply and manuals. 

So, here is the project at hand...a stock, but non-working HW-7, with full documentation.  Sure...this sort of thing has been written about and chronicled DOZENS of times in the last 45 years, but, this one will be done by me. 

WHY THE HW-7?????

I asked myself that a few years ago.  I didn't have an answer, other than the fact that I love how crude they are, and with the 40673/CA3035VI combination, it is really close in construction to my beloved and long-gone Ten-Tec Powermite 1 that I had back in the early 1990's as a Novice.

The active components in this antique are obsolete, to be sure.  The 40673, while scarce, is still available...albeit tough to find.  The CA3035VI shares the same status.  In the upcoming weeks and months, I will be making compatibility lists and posting links and charts so that future restoration buffs can be aimed in the right direction.


SO...Happy 2018 (yeah...it's late March)...and 73 from WNY.

Thursday, December 4, 2014

The Chinese Pixie 2 QRP Transceiver-An Asian Twist On An Old Favorite

Many hams have read about, heard about, or even used/owned a micro transceiver that is the essence of simplicity itself.

The radio I'm referring to is the much loved AND reviled, and misunderstood "Pixie 2".

The origins of this radio are familiar to the ardent QRP enthusiast.  The original radio, called the "Foxx", was invented in 1982 by George Burt, GM3OXX.  It was a simple, 5 transistor rig, that produced a WHOPPING 2.5 watts of RF on 40 or 80 meters.

Soon after, Oleg Borodin, RV3GM slimmed it down by eliminating one of the amplifier transistors and a few other "non-essential" components.  This, of course, became the "Micro-80" transceiver.  This radio is the closest cousin to the Pixie, in that, the oscillator stage appears to be quite similar.

Finally, WA6BOY's version of the radio eliminated the transistor audio amplifier stage and used an LM386 I.C.  This is the version that we still "use" today...almost 20 years later.

The Pixie 2 can be breadboarded out of junk box parts, or acquired all at once from a few vendors that sell the Pixie 2 in kit form.

The first, and most widely known is the version available from Halted Specialties, or simply HSC.


I have built three of these kits, and NONE of them worked very well...or at all.  The last attempt was a 30m version.  The quality of the circuit boards is atrocious at best, and for the beginner, this kit is better left alone.  To call it garbage would be too much of a compliment.

Next is the QRPme kit that Rex Harper sells, the Lil Squall.

I have known a few people that have bought this version, and they really like it.  The quality of the kit is outstanding, and having a custom made enclosure included is top notch.  Rex stands behind his products as well.  This Pixie has the unique advantage over the other kits, in that changing bands is a simple as changing the daughter-board with the appropriate coil settings for the band.  Nice touch!

Next is the RadioKit Pixie, available on eBay from Yiannis Kontarinis in Athens, Greece.
I have no information on this radio, so I can't really say much about it, other than its cosmetics.  It's not as attractive as the Lil Squall, but it is still pretty sharp looking.

And FINALLY...the version available from DOZENS (and I truly mean DOZENS) of sellers in China...

These kits are called the "Shoes" in China, although I believe that has something to do with how the word "Pixie" is translated back into English.  It is the same two-transistor circuit, with LM386 for audio amplification.

However, there are a few nice changes with this particular version.  Firstly, this radio has a 47K variable resistor that allows for a few KHz of tuning around the crystal frequency.  While it was also something that is featured on the Chinese "Super-Rockmite"...and allowed the TRANSMITTER to also QSY a bit, this one is strictly for the RX only.  Next is the rather beefy BNC jack.  This is a DRAMATIC improvement to the typical RCA jack that is used for the RF connections on many Pixies.  And finally...my favorite thing about this radio is the PRICE!  I bought mine direct from a Chinese seller on eBay (although you can also purchase them directly through China's domestic shopping site, Taobao.com) for $7.59...and it was shipped FREE from China via China Post.  And there are many sellers that sell them for as low as $5.50 with free shipping. 

The true reason that I bought this Pixie was due to an unfortunate accident that I had with my Super Rockmite, which I have currently written about before.  I was connecting my Ten-Tec KR5 keyer to it, but after doing so, the RM went into a wild self-oscillation that quickly destroyed the 8W behemoth.  Being so close to Christmas, I wasn't able to afford to replace it.  That's when I saw the Pixie.

The radio was ordered on November 7th, and shipped out the next day.  The worst part of shipping from China is the wait times in Customs.  But ANY international commerce is rife with delays like these, and having purchased many things directly from the PRC, I was familiar with the wait time.  The radio arrived in Buffalo NY 11 days later, as expected.  

The kits all come in padded envelopes, and when opened....this is precisely what you get:

And that is LITERALLY all you get. 

NO instructions.  Nothing but your circuit board and a small baggie filled with parts.

In order to make this work, you have to do a little legwork.  That's why ALL of the schematics and parts lists are on the sellers' pages...and they ALL do it this way.  I like to think that it keeps the costs down by not having to photocopy instructions over and over and over again.

Back on the seller's page, you find THIS:

Thankfully, the English translation is on the parts list.  And with this information, AND the fact that the circuit board is marked with component locations (R1, D2, etc), it's not too difficult to get the components roughed into place and ready for soldering.

In addition to the parts as listed, I also ordered a 7.030 MHz crystal from Rich at ESS.  For $2.95, he sent the appropriate crystal for this rig.  For some odd reason, almost 100% of the CW rigs that you buy from China come equipped with crystals for 7.023 MHz.  As a General Class ham, I can't use 7.023, and I don't think I would want to...since QRPers hang out around 7.030-7.040 anyway.

The rig goes together fairly quickly, however, it must be noted, as it is on a recent YouTube video describing this rig, the kit comes with A LOT of extra parts...parts you DO NOT NEED.  I don't understand the reason for this...perhaps the person putting the kit together ran out of needed values, and added a bunch of stuff as a "good faith" gesture...but this just adds to the confusion.  As in the video, I too, had to add my own resistors...a 1K and the 33K to be precise.  They did not come with the kit.  THANK GOD Radio Shack still sells some components.  In the meantime, while not wanting to wait until I got to RS to buy some 33K resistors, I simply paralleled 3 of them at 100K ohms per...and it worked just fine. 

The solder pads underneath the board (and it's a through-plated board...nice touch) are tiny, so a small iron is a necessity.  I have an 18-watt iron that has a tiny pencil tip that saved the day.  You WILL need a larger iron for soldering the coaxial power jack, both of the 3.5 mm jacks (key and audio out) and the BNC male RF jack.

Total build time was just under and hour.  Your mileage may vary, depending on your comfort with a soldering iron and how much light you have in your work area.  I say this because some of the components are TINY...and the markings can be difficult to read.  At 42, I am beginning to wonder if I may be needing bifocals soon.

After nipping off the soldered leads under the board, I connected my antenna and earbuds (iPod style work QUITE well in this little radio) and then the power...and was delighted to hear 40m spring to life.

The audio is TYPICAL Pixie 2...it's as wide as a barn door...but the sensitivity is actually very good for what this little toy is.  If you've ever used an old Heathkit HW-7 (with the 40673 for the detector), it's comparable...except there are NO microphonics.  

When using this, or ANY Pixie that is using the LM386, a few things must be adhered to for the best possible performance.  For starters, using a power supply is not recommended, as you WILL HEAR HUM.  Write it in stone.  Battery power is where it's at with this rig.  And many like the idea of being able to use a 9V battery due to size, but the 9V doesn't supply enough current for the Pixie to both transmit enough power AS WELL AS not current starve the LM386.  Many hams complain of the buzz or motorboating sound when attempting to debug a misbehaving Pixie...and sometimes it's BECAUSE of not enough voltage/current.  Secondly, a good antenna is essential.  I was able to hear QSOs in progress and even be reported on the Reverse Beacon Network while connected to my Opek HVT-600 portable antenna, but with a proper antenna such as a dipole or an end-fed (such at the antenna I sue at home), the audio really wakes up.  

At my home QTH, I am 9.5 miles away from WGR550 AM's transmitting tower.  I was able to hear it when I had my HW-7, and occasionally I can hear it through the Pixie.  Some cures for it are to ground Pin 7 of the LM386 via a 10 uF capacitor.  I have done this and it works very well to mitigate the BCI interference.

On Monday night, December 1st, I made a few CQ's and was answered by N2BHA in Rome, NY.  We had a nice QSO, while I tried to contain my enthusiasm.  Sure, it's only 165 miles from point-to-point, but the fact still remains that it IS a radio capable of REAL communications.  I know that I will be installing this into a typical "Altoids" style box (although mine is a blue Newman's Own box...I like to be different) and also will be adding a a K1EL K-16BAT kit so I can use an Iambic A single-lever paddle.

In summation, this is a nice, BASIC, NO-FRILLS radio.

PROS:
-COST
-AVAILABILITY
-EASILY EXPANDED

CONS:
-BCI OVERLOAD IF IMPROPERLY GROUNDED, ETC
-LACK OF INSTRUCTIONS
-EXTRA AND MISSING COMPONENTS

73/72 de KB2HSH


Tuesday, June 10, 2014

The COMPLETED Chinese Super Rockmite/Octopus Clone


In the photo above, you see the finished result of all of the pieces and parts...fit together just right.

I originally went looking for Dupli-Color DE1618 to give it the "Heathkit" look, but settled on Ford Cayman green.  It resembles the Heathkit green, with a little extra gold sparkle to it.  The case accepted the primer and paint very well, and it has a smooth finish...much better than the raw aluminum case.

I even painted the MFJ CWF-2's box to match it.  They are roughly the same size...so they look pretty neat sitting next to each other.

Also, I re-crystalled the board, as stated before, for 7.030.  There is MUCH MUCH more activity on 7.030 than 7.023 MHz.  Just yesterday alone I made 5 QSOs at random times during the afternoon/evening.

So...all together, I spent $40 for the radio...$22 for the case, $11 for the crystals (from QRPme.com), and $7 for the paint.  Grand total: $80.

Next step is to build the "CT1IAO" portable single-lever paddle to use the internal keyer:

http://youtu.be/euuQJ-DXrgo

Next step...take 2:  Testing it portable with the Opek HVT-600 antenna.

Thursday, May 29, 2014

The Chinese "Super Rockmite" Clone

Recently, I was perusing my Twitter feed, which I have to admit I haven't been keeping up with.  Recently, my Twitter friend Matt, W2MDW posted a link to an eBay page showing the "Super Rockmite Clone" radios.

These radios are available in either kit form OR fully assembled...but that's not what makes them unique.  I have written before about the Chinese versions of Dave Benson's (now Rex Harper's) "Rockmite", known in the PRC as the "Octopus".  The Octopus is LOOSELY based upon the Rockmite...and the Super RM clone is even more of a departure.

I bought one of these radios for portable operation with an Opek HVT-600 antenna while at the YL's house.

The BEST part of this radio is the WHOPPING amount of power that it emits.  The CRK-10 was a stout little performer with its 3 Watts....but the Super RM Clone is an EIGHT WATT RADIO (@12V DC).  

YES....8 Watts.

There are some interesting upgrades with this particular radio, as well.  There is a DB9 port on it for what the website calls "PC Keying", but the software is difficult to find, as is the cable required to make it happen.  After quite a bit of navigating around ENDLESS Chinese websites, I was able to find the software, schematics, and instruction manuals for the rig.  


The Super RM is far from perfect, mind you.  The audio is anything but pleasant to listen to IF you are using regular (a.k.a. CHEAP earbuds....or "walkman" style headphones).  It is SO LOUD and SO HARSH as to not be comfortable for very long.  And, without a little tweaking of the sidetone pitch (via button 1 and 2 on the top of the circuit board), your keying sounds will drive you CRAZY.

The solution was fairly simple for me, since it had worked with the MINT CONDITION Heathkit HW-7 that my ex-wife bought for me last year:  1945 vintage Telephonics Corporation TH37 headphones and an OLD MFJ-CWF2 filter.


The old heapdhones in conjunction with the filter (when needed) really take the harshness out of the audio.  Your mileage may vary, but it is an ABSOLUTE improvement for me.

There ARE a few significant downsides to this radio in the "assembled" state:  ALL of these radios are coming from China with crystals for 7.023 MHz.  Extra Class license holders are the only ones allowed to use this frequency.  ALSO...the Super RM Clone uses THREE of the these crystals.  Two are for the filter, and the third is for the oscillator.  But, affordable crystals can be had by contacting Rex Harper via QRPme.com.  

I QSY'd mine to 7.030...the QRP "watering hole" for 40m CW.

And there is no case with the radio.  However, the matching aluminum box can be obtained by a quick trip to eBay.  

All in all, I paid $40 for the assembled kit, and another $15 for the matching aluminum box.  And when you purchase from the MANY eBay sellers, shipping from China is USUALLY free...another perk.  Arrival to the US is typically 7-15 days....mine came in 11.

More of these rigs can be seen on China's domestic shopping website, Taobao.


Make sure you are using a GOOD web browser, such as Google Chrome, so you can have the page translated into "Chinglish".

As I make changes and improvements to the radio, I will be posting them here.





Friday, December 13, 2013

The Capabilities of Weak Signal Digital Modes

Since the beginning of the "Amateur Radio Service", we hams have almost constantly sought out news ways of doing one thing: communicating.  We switched from spark to CW for many reasons...but namely, CW was vastly more efficient.  AM is still with us, but primarily, we use SSB.  Why?  Single-Sideband "goes farther".

The same is true for the soundcard digital modes.

Some modes are better in adverse conditions than others.  Some are more efficient, and are able to convey the same amounts of information, while sometimes using less power to do so.

The following is a list of popular digital modes, and the typical minimums of signal-to-noise ratios that allow their transmitted information/signals to be copied:

JT9-30..............................-42 db ("QSOs" can last 3 hours or MORE!)
JT65...................................-30db
Jason Turbo (Fast)...............-25db
FT8.....................................-20/22db
PSKAM10..........................-20db
PSK10............................-18db
MFSK4............................-16db
Contestia 500/32.................-15db
DominoEX-4 ......................-15db
FEC-31...........................-15db
THROBX-4.........................-15db
Olivia 1000/32...................-14db
Olivia 500/16....................-14db
THOR11...........................-14db
MFSK16...........................-13db
Contestia 500/16.................-13db
CW 20 WPM......................-13db
RTTYM 500/64....................-13db
THOR16...........................-12db
MFSK31........................-12db
Olivia 500/8.....................-12db
DominoEX-8........................-11db
MT63 500Hz BW....................-10db
Olivia 500/4.....................-10db
PSK31........................... -10db
CHIP-64...........................-8db
DominoEX-11.......................-8db
MT63 1K...........................-7db
PSK63.............................-7db
Feld Hell.........................-7db
CHIP-128..........................-5db
RTTY 45...........................-5db
PSK125............................-4db
PAX2..............................-2db
PSK250............................-1db
HFPacket (300baud)................+1db
PSK500............................+3db

Right away, we see that the old-timer's MYTH that "CW gets through when no other mode will" no longer applies.  At -13 dB under perfect conditions, we see that there are AT LEAST 15 other modes than can do the job BETTER.  If a simple signal report is all that is needed, JT65 is EXCELLENT when used with QRP power, or when faced with QRM, QRN, and QSB.  Quite simply...there aren't many that are better. JT65 can be copied with almost over-lapping signals.  (JTDX 18.1.30 is arguably the most capable of the few suites that CAN do JT65).

But how about times when you want to have an actual conversation with another station...or you need to convey more than "WX1XYZ KB2HSH -12" ?  For "rag-chewing" during poor/weak-signal conditions, Olivia 500/16 or 1000/32 and Domino EX-4 are able to copy at signal levels 2 to 3 dB LOWER than CW.  This can be handy for that elusive QSO.

A few years ago, I was having a QSO with a German station on 30 meters.  We were using Olivia 500/16.  When we began the QSO, the signals were audible as well as visible on the waterfall.  As the band began to close, 30 had deteriorated to where we could no longer see or hear the signals, but we still had solid copy throughout.  It was that QSO that convinced me that digital modes were not only superior to the older, ANALOG modes, but with the QRP power levels I use...they are VITAL.

During periods of good band conditions, many use the faster modes.  There is nothing wrong with that...but when using modes such as 300-Baud Packet, or PSK125, you will simply not get the distance that you might otherwise obtain with the slower, narrow modes.  Case in point: the IS0R DX-Pedition to Sardinia recently.  Now, Sardinia isn't exactly exotic, but on 80 meters, this would have been great for my 80 meter DXCC total.  80 was in decent shape, but they were using PSK63.  I had 80-90% copy on them...and I stood a good chance of working them, IF they had used a better mode.  Instead, they switched to PSK125, and the game was over.  By the time they switched to PSK31, it was too late.  The band had gotten lousy, and the pile-up was growing larger.  The error made was when they switched to a mode that was wider, faster, and capable to -4 dB S/N.  Too bad they didn't use PSK10!

It should be noted that many of these modes are only found in MultiPSK. 

With the aid of this list, it should give the digital operator a big boost when trying to increase their DXCC totals.  Granted, some of these modes aren't very popular, and finding another station that is using them may be difficult, but using the right mode for the right time, conditions, or needed applications can be the difference in successful QSOs...or none at all.