Hamfests circa 2020

I went to the club near my second house, intention to retire to, down in Sierra Vista, AZ this weekend and picked up a couple of toys.. I should be selling... But no, I bought... I did manage to get a couple of decent deals.  I joined the club too, lucky them... 

Of course one of them was a Zerofive GP1040 antenna which is the smaller version... 27 ft radiator or 29 ft overall of the 43' vertical that I am building at the place, but with an elevated ground structure TIG welded to the base insulator.  It will be interesting to compare it with the many ground radial (so far 71 and I do intend to get to 120) also non resonant 43' vertical I have been building from tubing from an unfinished project in Iowa.  The difference from past HF ground mounted verticals with only 32 or less radials is pretty remarkable, honestly, so far and due to, I am not kidding, 40 MPH plus winds for the last 8 weekends or so, I only have 16.5' up for a 1/4 wave  (resonant) on 20m. The higher bands were cooperative the last few weekends so I know at least on 20m and up the radial field is a winner so far.   First and only contact so far on that and my Chinese Xiegu was of course Moscow because I do have that sort of dark sense of humor. 

Yes--the Zerofive is built like a brick outhouse just like everyone claims.  The sad thing is that the mounting pipe and concrete from the Home Despot will cost more than the antenna did at the 'fest.  

I want to see if the six 100" radius elevated radials are as good as so many NEC modelers claim (they haven't been in the past in my experience especially compared to what I now have).  And if not that thing will probably end up ground mounted and extended to 33' as a committed 40m antenna.  So the impulse buy of that antenna that I probably really didn't need was a good one likely long term.

Anyway though, I am 53 years old now and am trying to buy toys in advance of retirement.  I am starting to wonder if I will be the guy who turns off the lights with ham radio, and with many other good things in life.  I still am one of the youngest people at these events.  Radio to me is still black magic, and it's a lot like the railroads.  The utility will always be there.   So will the black magic... 

I just don't know if the hobby still will be there.  I don't know how to get younger people interested either.  It doesn't even give you the slightest bit of advantage now in hiring as an engineer like it used to.  It's probably a detriment now as that flags you as being old. 

So you OMs out there need to hold on a bit longer so I still have someone to work in 5 to 10 years, record inflation notwithstanding, maybe longer until I do retire. 

I love to build more than operate so that is largely what I have done in my limited free time.  Hopefully that can change in the next few to hopefully not several years. 

The hamfest was fun and good.  The club down there is extremely well organized and has a great spread for emergency comms and a clubhouse and antennas that are enviable. 

But I tell ya, it's no Peoria IL Superfest circa 1989... Not even Peoria IL was 15 years ago.

I can't imagine what they were like in the Golden days like the late 50s through early 70s.

Well, maybe I can.  A lot of the same equipment is still for sale at today's hamfests.

I am starting to resurrect my amateur satellite equipment, and also not like the golden days which I did experience, I kinda miss it but there really isn't a lot of interesting stuff up there now.  Enough to justify the project though.  

So I am starting to build a K3NG rotator control to replace the FODTrack (dates me right?  Not like the stuff YOU were selling at the hamfest, though!) that I had attached to the G-5500 control box.  I will have more on that mañana... Nice software but the sheer amount of compilation options gave me the tics... 

73 for now... Fred W0FMS/7

The internet is scary and so are 43' verticals

 I disappeared for about, what 11 years, and just looking at this, I was able to log in with my Google Account.  So hmm.. Maybe I will bring it back. 

My free time for ham radio, which was never a lot really slowed down around ten years ago. My now adult kids became most of my life around then, work got worse, and what little I did post ended up on Facebook groups.

Like many people, I started to get shadow banned and get periodic 24 hour bans for saying stuff that wasn't bad about a year ago. My political views by any norms are mostly harmless but still I started to get in trouble there.  The final straw for me was saying "If I told you I would have to kill you" to a comment, totally in a positive context too... In my line of work that's something you jokingly hear at least once a week. It got me the last 24 hour ban that Facebook will ever give me. 

They then a couple of weeks later tried to recruit me via LinkedIn.  It's the only time in my life I explained why it was a big no. 

I did try to get back on as a regular at AmateurRadio.com but despite Matt the editor saying he'd restore a login for me, it never happened.  Just as well, even that was about a year ago and right after that I had a year of major disasters.  You probably had a bad 2021, but I assure you that I had it worse.

About 5 years ago I moved to Southern Arizona for a new job, and have more or less been in HOA hell.  I mitigated it somewhat by becoming the HOA secretary and luckily we are in a subdivision that's not militant about it.

I also just bought what is a weekend place that hopefully I will retire to eventually about 45 miles SSE as the crow flies from my house in Corona de Tucson.  12 AC, enough for a 550' Beverage again if I desire.  I had enough Aluminum tubing to start on a 43' vertical. I actually have 71 radials down this time for the first time.  Various lengths.  Only 16.5' up because it's been windy every weekend for like the last 8, and I don't have rope guy points in yet.

Brought my Xiegu G90 there and finally hooked it up two weekends ago.  First qso on that rig and antenna (and it's not even done) was to  R5AJ in Moscow.  On a Chinese rig..10w pep SSB is what I set it to for "official QRP".  I do stuff like that because I have a dark sense of humor.  The bands are coming back.  I think cycle 25 is going to be at least 23 intensity, the current predictions are wrong... Too low.. 

I will detail that and some other stuff I am working on in the next several weeks.

Why is a 43' vertical 43 feet?  It's 5/8 wave on 20m, and long enough for 30m and 40m.  Without top loading of some sort its dicey on 80m. But you get some additional low angle gain on 20m and the pattern is quarter wave ish on 60m (it is almost a quarter wave there), 40m, and 30m.

With that antenna being so hyped its sometimes hard to get that basic information. It's non resonant everywhere except for 60m where it's "almost" resonant.

Where my build is different is that I am trying to mark the quarter wave points so with my tilt over base I built I can easily change it to a, quarter wave from 40 to 15m or so.  Anything higher than that a dipole on a stick would be better. 

I am not going to do a tower again.  And the scrub in the high desert is velvet mesquites.  They don't get very tall.  So for below 20m it's gonna be verticals this time for sure.

I have less land at the new place than I did in Iowa but I don't have to lease any of it out for farming which put a bigger cramp into the ham radio antenna field than I ever imagined.  It's why I had aluminum tubing in a bag and never up.

Ciao for now. 

Fred W0FMS/7

Expired beverage

Sad thing is that because of a bunch of crazy stuff in my personal life I've not had time to operate much or blog at all.  Around early December, I finally got a Beverage antenna up (with respects to the late Dr. H. H. Beverage).  I just took out the portion of it that crossed the rented land for the farmer.  I used it three times.  Apparently I have a strong noise source in my house somewhere that I have to debug (uugh), but I was able to phase it out with my modded MFJ-1025.  I had a bit over 1000' feet up in December...

Above is the portion of the plowed field.  I took that out last Sunday  :O(  But I still have about 700' left in the woods and it appears I can expand it out in another 200-250' year around.  :O)

My house and garage are oriented NE of the antenna, of course, so the two wire is needed.  With the local noise source that worked out well anyway.

Above is the section in the woods.  I can go farther.  If I can get my neighbor to agree to let me go into his land a little I can get back the 300' or so feet I lost in the field.  If not, I can go 800-900' permanently.

In  the Midwest, our ground is a little better than is posted in most of the handbooks.  It appears on better soil, longer Beverages work better than on either coasts.  My 1000' long one was FAR INFERIOR to my friend Jeff Woods, W0ODS 1/2+ mi long antennas on almost all bands.  I could hear Algeria on Long Wave with this antenna-- it was full quieting on his.  He's heard Commando Solo in Afghanistan at 3 MHz before on one of his Beverages.  It's cool stuff if you live in the country.

He taught me the appropriate method of constructing these to survive the rather windy Iowa winters..  That is 16 ga Aluminum electric fence wire.  Proper fence posts (cast, not "bent") and 1-1/2 PVC, no smaller.  Holes to run the wires through with slits cut in with a hacksaw (or in my lazy case a diamond saw from Harbor Freight with the holes Dremelled out).  Here is a picture:

This works out really well.  The transformers were homebrew.  I use "Balun" type cores, mix 73 because I had them... two cores wrapped together.  The MFJ antenna analyzer is very useful for proving them out before hooking them up.  I ought to post something about that but that'll take time I don't have now.

Anyway.. the sad thing is I used this 3 times during my Christmas break and that's it.  I miss ham radio and writing about it.  Maybe I'll get back to it again.

I can run a shorter one year around.  But the bad thing is that I need like 300' of RG-6 (times two) to get to the wood part of the Beverage.  Ideally, a remote controlled phase box with the Beverage pre-amped would be the ideal setup.  I don't think anyone makes one.  Yet..  Another project I can start and never finish... sigh.  But it would be cool to have a phase box at the beverage termination (at the right impedance w/o a transformer at the fed end even) and then amplify out the 300' of cable.. it's a receive antenna anyway so it's very possible.

In the mean time I'm going to post a few words about a relatively new hobby I can do at least 1x a day.. that's coffee.  I'm going to start a new blog, "Cheapskate Coffee" and write a little about the beginnings of Specialty coffee and home roasting but without spending a fortune.  I will eventually spend a fortune on that too I suppose.. but not yet.

Until next time.. hopefully not 6 months... 73

Arrgh....*poof*..

The DigiLite DATV project has taken me on an interesting (and kinda expensive) tangent in the last few days.

About 2-3 years ago, after years of doing small Micros and PIC processors, I decided to try out the AVR and the open source WinAVR GCC tool chain for the AVR's.  I never did get into Arduinos except for hardware-- I bought a few Sanguino boards which are an ATMEGA 644P version.  I got shipped 644's instead of 644P's and it wasn't worth shipping back (my order was correct, the shipment wasn't).. so I used those.

I decided that for the DigiLite DATV project to make my own programming board for the "Ultram Tech" PLL board rather than using the BATC Closed source or F1ACN "demo PIC basic" solution.  Initially, I didn't want to do the software work required to use WinAVR (see previous posts when I was working on the HF amplifier-- which I will get back to someday!), so I decided to see how "beneath me" the Arduino IDE actually is/was.

I'm actually fairly impressed by it because it does actually hide the GCC tool chain within it so the actual hit to the performance and RAM is minimal.  It is really well designed.  In the meantime I decided to order off a Chinese clone of a Arduino 2009 and  a LCD shield to go with it.  It cost $29 shipped for both.  It will be the "GUI" for the PLL project.   The physical packaging is nice.. it'll be nice and really that inexpensive PLL with the inexpensive control could also make a really nice "poor man's microwave signal generator".  The commercial Arduino 2009 version has a FTDI serial chip on it so ideally my version will have both a 2x16 LCD display and also USB (CDC serial emulation) control over the PLL.  I'm getting more functionality out of this unit for less work and $ than the two PIC based solutions.

I think I am going to post on Amateur Radio.com a "Zen of Arduino for Ham Radio" describing the potential uses of these little devices and a small quick tutorial (maybe here if it gets lengthy or too technical).  Anyway.. all is well with that project.. It took me about 20 minutes to build up a Sanguino and a HD44780 display and write 80% of the GUI for the PLL.  This was before I got the e-bay modules (which are quite nice).  To port off to the real Arduino (ok clone) took literally 10 seconds.

I'd have the whole thing done now.. but I need to figure out the control words for the PLL chip... this will be easier when I actually receive the PLL.

I can see the reasoning for "Arduino" even though those are slow, 8-bit processors that are a bit pricey for what they   are... but for someone who wants not to delve into programming these are ideal.

Anyway.. I also decided that I should use these to teach the older boys how to start programming rather than starting them off on Linux or MS Visual Studio.  So I got the "wild hare" up to dig out another old project--

About three years ago I bought a WizNet812MJ (W5100) module for about $35 with shipping (which was expensive IMHO) to do the DVB-S project on a FPGA.  The intent was to use Ethernet at the max 20 Mbps SPI rate the W5100 was more or less capable of.  I did get it to go with a small micro, but at the time the code to do the stack was substantial and I ran out of time.  In the closet that module went.

I decided, hey, the Arduino Ethernet Shield is basically the W5100..the arduino has a nice library for it.. no work, right?   So I made a breakout for the breakout, and put a L78L33ACZ 3.3V regulator on it and wired it into a breadboard.  What I didn't realize is that on the Sanguino board the SPI is currently "broken" on Arduino >-019 .. it's fixable but it's not a simple fix.

I almost had it.  (It has to do with the Arduino code not knowing the different pinouts of the SPI UART on the ATMega644)..

This is only a minor ARRGH.. though.. I was on my way to find out the issue with the module..  It is, by the way 3.3V but 5V tolerant for the inputs.  One thing that has to be done is resetting the chip.  I did this by tying into the RESET on the Sanguino.  I didn't yet (I'm getting some from...yes..e-bay china) have the little push button reset buttons.  So I have been resetting with a jumper wire.

Well.. guess what I did when I almost had the SPI issue resolved on the Sanguino/ATMega644/Wiznet?  I bumped the unregulated voltage when resetting it.  The Wiznet W5100 is 5V tolerant.. but it's not 8V tolerant!  :O(  The LCD was fine and the ATMega was fine.. no it couldn't have been something I had multiples of that is easy to get.

So it happens to all of us I suppose.  The bad thing here is that it costs about $25/module now with shipping (I did buy two more because I do have a couple of future projects and I want to teach the kids by making a little sensor driven Internet device-- weather station maybe?) and I also decided to buy an actual shield from.. yup... China.  I wondered why the lines on the Arduino shield are buffered on a 5V tolerant chip.  I now know.  So in a millisecond it cost me about $75.  OK the $25 for the shield was coming anyway probably.. but $50 for two more modules.. not so much.

Lesson:  don't do something that stupid.. or if you do put the chip reset on a GPIO line!

The good news (as it is) is I fired up the X-Tronic hot air gun and got the chip off without totally destroying the board.  (It looks good and I didn't drop off anything from the bottom!)  So if a place that charges reasonable shipping (Saelig is out, for example) and doesn't require minimum order of 5 of them (like WizNet direct or Jameco).. I can fix the module.  SparkFun carries them but are out of stock.  So if a SparkFun guy sees this I'd like the $6 solution to the $4 problem too to fix the module I have.  !

Like ham radio.. electronics is an expensive hobby.  But I do love it and I guess since it became my life and living I am blessed.

But boy do I feel downright dumb tonight.

DigiLite update...and SOAPBOX

I did go off and order about $150 total worth of parts for the DigiLite.. I'd guess to get to the "modulator stage" of a DATV DVB-S transmitter that one would need about $275-300 if buying all new.

I also ordered the $55 Ultram Tech (from Israel..e-bay) ADF4360-6 based PLL oscillator board.  I am going to write my own control that will use a $29 Arduino 2009 board and a 2x16 HD44780 based board with buttons from e-bay (China) rather than running the "5-button" PIC board hack-up the BATC is running.  I need to be able to set my own frequencies, so I need source!  I have most of the code done already (Arduino is sooo easy..) but I need to figure out some of the settings that the Analog Devices Integer-N PLL / OSC uses.. like "current setting" and "antibacklash".  I don't have the Arduino yet.. but I converted some of the Sanguino's that you'll see in earlier posts to actually be Arduino based instead of hacked with WinAVR as I had been using them.


And Yes.. If I do this, it would be a "bang up" poor mans signal generator for 1200-1400 MHz.  Code will be open source...   Note also that there is a French Ham doing a version and there appears there may also be  a board when the BATC CQ-TV 235 comes out in October 2011..  okay.. we are past that.. now.. so "soon."

I ordered $80 of parts from Mouser for the Chip Tantalums (expensive!** only one is really needed for the DSPic33) Bourns Surface mount trimmer pots.. weird SMT 3.3V regulator***, a couple of PICs, and adjustable regulators for the biasing of the IQ circut.. and other bits).. oh and the $27 FTDI module.  By **expensive-- I'd eliminate the stinking chip tants-- which I hate-- if the board was re-laid out and replace with common leaded electrolytics.. I'd use standard leaded pots, ***a leaded 3.3v 78L33 type regulator.. those little things would make the board an inch bigger in one dimension but probably cut the parts cost by $15.)  I'd also consider the four port FTDI module FT4432 instead of the FT2232 and use one of the extra ports for SPI programming of the Ultram Tech PLL Oscillator and .. maybe an extra RS-232 port with a line driver on the board?  Actually, why not put the PLL chip on the board as well and not have to buy the synth from Israel?  (No offense here to Ultram Tech.. good service so far)

All parts can be had from Mouser which is the cheapest overall source other than the Analog Devices modulator chip.. the AD8346ARUZ..  that is a Digi-Key or if you must Newark part.

I programmed my own DSPic and saved the BATC pre-programmed one for a second board.  I was going to also order another board from the UK and build it up for 70cm.  I can't do that.  I do NOT believe it is legal to do so in the US.  Many including N1ND who is the frequency rules guy at the ARRL disagree with me.  I'll briefly mention why I do not think that DVB-S/C/T or even ATSC is legal on the ATV frequencies on 70cm at the end of this post.   I might build a second 1255 MHz unit and loan to other local hams so we could do a two-way.. or maybe I'll eventually build up a 33cm unit.

Anyway.. interestingly enough.. the DIP adapter for the PICKit3 I bought to program DIP based PICs wouldn't work the DSPic33... but a breadboard did!  If there is interest I'll write up how to make the programming on the breadboard with the PICkit3.  Basically hook up the power to the right places and the ICSP lines and power from the PICKit3 and it works!  The lesson here:  the bread board is the UNIVERSAL dip adapter.. don't waste the money of the ZIF adapter board unless you are programming a lot of parts!

Anyway.. I don't want to ramble to much, so lets cut to the chase.  I don't have the Oscillator module yet, so
I fired the unit up with no LO drive and no MMIC pre-driver installed...

It works...  At least up to the modulator out from the DSPic33..  Here is a short video of a "government cheese" NTSC SD-box receiving PBS on the Hauppage PVR-150 with WinTV-6 and then streaming it out with the BATC's software to the PIC which at least thinks it's modulating the signal to QPSK (and would if I had a LO and properly adjusted the I/Q offset/drive).  So it's really close:

So yeah.. it works like greased snot.  It's slick.. and impressive.  There are a bag of tricks to make this happen like the MPEG-2 Conexant chip on the PVR-150 configured (in that case, for 3000 MSym/s and 1/2 FEC for 3 MHz wide signal) for a CBR MPEG-2 NTSC D1 video rate of 2222 and MP2 audio rate of 128K which is really quite sufficient for ham use.. actually.. I'd like to experiment with narrower signals!

At 2222/128 the null packets are very small and most times there is negligible PCR lag.. occasionally though the start-up seems to throw off the DSPic33 at this rate and a restart is necessary for a non negative PCR lag.  at 2112/128 this seems never to happen but null packets are about 4.5%.. so somewhere in the middle of the two is probably perfect if you want to run 3 MHz wide D1 Video with decent, but not-quite music quality stereo audio!  That's at least 1/2 the bandwidth of analog ATV.

<SOAPBOX>

Meaning this should be a shoe-in for the 70cm band!  Much better than 2x the quality and 1/2 the bandwidth! Super lets start using it?  Not in my opinion.  Part 97 defines image on Frequency and/or Phase Modulated signals as designator F2F or G2F only.  Commercial definition from researching license grants to commercial parties show that ATSC is 5M38C7W (or in ham speak C7W) and DVB-S as G7W.  No exceptions.. I did not find ATSC defined as C2F or DVB-S defined as G2F anywhere!   These designators are explicitally defined in Part 97 as "multiplexed data". "7" and "W" are excluded from Image!  So even though there is a clause that states that undefined or digital modes that are substantially the same as the analog equivalent in bandwidth for phone and image are legal.. Legally DVB-S/C/T and ATSC isn't IMAGE.. it's DATA.  And data is (WRONGLY!) limited in the 1980's rules as 56K baud (symbols per second per carrier) and 100KHz BW .. so even though NTSC video is not legal anymore anywhere else.. ATSC is mandated.. it's illegal in 70cm under current rules but NTSC isn't.

Yeah, would the FCC enforce this or care?  Nope.  The ARRL doesn't care either apparently.  It doesn't change the fact this is what the law says.  This is a warning, people.  The rest of the world is going digital and as hams we are not.  Are rules are a major reason why.  They were intentionally set up in the 1980's to make digital modes second class citizens on the ham bands.. or at least new digital modes.

If you disagree with me and run DVB-S/S2 or DVB-C and some have on 70cm... good luck and I wish you well-- I support you.. but I see it as not permissible.. which is really quite unfortunate.  It's legal in most other countries that don't have protectionist rules in their regulations.

End of my comments on this... </SOAPBOX>

One time rant, get it off of my chest.. then the DigiLite from BATC

Well, now that you can tell that I only am posting short messages once every three months or so, that life has gotten in the way of my other plans... including ham radio.

I've not been on the air since June or so, and had severe house and antenna damage in early July that-- although the monetary loss was minimal, took a lot of my SUMMER free time to fix.  I would often operate from the W0CXX club station at work, but they are re-roofing the building, and there are no usable antennas there either for quite some time.  So ham radio has been on hold.

I'm probably back to operational on 40m (at least with a low dipole), pretty sure I'm operational on 20-15-10m. My previously poor 75/80m tower feed can be fixed.. but with the 'spots being what they are lately I'm not in a hurry with that.

I want to complete my 12m/17m Moxon/Yagi combo that I've been building out of an old 10m Cushcraft beam. (When I prove that it works I'll post a 'blog entry on it here with an overview at Amateur Radio.com.)   I have a 6m 5 element beam ready to put on a roof tower on the opposite side of the detached garage from where I have the tower.  It will be a little lower in elevation but should be fine.  This has been in the works since spring.  I was also going to put up two verticals phased on 40m (and eventually load it for 80m) but I don't see that happening in 2011.  Sigh.. for a while there I was really productive with the hobbies.  I lost my wire 1/2 square for 40m when a tree fell through it, so it would have been nice to get the phased ones up.  Maybe next year.  If I don't move and put up everything for auction.  That's a different story though not related to the 'blog.  But it's sad.. I'm getting upset that I never have time for anything fun anymore.  I'll mention this once and try not to use the excuse I'm too busy anymore but it has been the truth.

The TS-590S I bought at Dayton has had ZERO transmit time on it.  And maybe a couple hours of RX.  BOGUS AND SAD!


I also started to gain some weight after hitting "bottom" with the gastric bypass.  It became obvious that I'd need to start working out to go from a "stick" (literally, people were telling me that I was looking bad) to at least gaining some inevitable weight back as muscle.  Okay, they *tell* you that 30-minutes of exercise a day is enough.. but it's not... really 4-5 times a week for about 1.5 hours at a time is what I found I need to benefit from it.

Rockwell Collins Rec Center Zagrata 5K 9/2011

But that's, what?, 8-10 hours a week less to do building and operating.  But it sure beats going back up to 350 lbs, .... that is for sure.

I even missed the Iowa QSO Party today because I couldn't get home early enough on Friday not to be exhausted with the 9AM start and everyone else in the family had other plans.  Only in Iowa would someone think that running a contest from 9AM to 6PM  on a Saturday was a good idea.  Hell, it would have been nice to have some after dark 40m/75m contacts, right?  I work 8AM-7PM during the week.  It's not fun to do that on Saturday.   If it would have been 9AM to 9AM or noon to midnight or something logical I would have done it.  But by the time I got home, and then got to bed at 3 AM I couldn't do the 9AM-6PM thing.. oh well.  I suppose the 3AM thing was my fault but as it is it was for a good cause..  I started on it well after 10 PM but I actually had the enthusiasm to do so for the first time in months.. maybe ham radio isn't over for me after all.

So maybe someone who has their crap together much better than I do can tell me how you can be a productive working age adult ham operator and work full time+, have four kids, a wife, and have to work out?  I don't want to quit but I starting to think I have to.  I now understand why ham radio is becoming a "retiree's" hobby.

Anyway, why was I up to 3 AM?  I received a care package via "Royal Mail"  on Friday.. and it's something that was designed almost the same way (actually more clever in many respects) that I had been thinking of doing for close to 10 years.  

British Amateur Television Club "DigiLite" DVB-S serializer and modulator, top side 3/4 done

Bottom side, probably more than 3/4 done

Anyway.. one comment of pride:  I haven't yet ordered parts for this board.  About a year ago I started to buy parts kits from (mainly China and Thailand but) all over and stocked up modern useful parts for a fairly low cost.  Needless to say I have the board 3/4 done from my parts kits.  I did identify an issue where I need to stock chip tantalum capacitors or chip electrolytic as I have had more than one case of not having them when I needed them.  Okay.. I cheated slightly in that I paralleled a couple of 0805 capacitors to make an equivalent of the called for 1206 value.. and I used 0805s for most of the capacitors (which fit) since it's easy to get good quality kits of 0805's from Sure in China but no one has or normally uses 1206/1210's in industry so you won't see cheap kits on e-bay.  I think I was lucky to find a US source for a 1210 chip resistor kit (which ultimately was from China).

Chip resistors are typically less than 1 cent bought that way.  Newark wants upwards of 15 cents/ea for one.  It makes sense to stock up on chip components for the coming apocalypse -- it's typically cheaper to do so than to order specifically for one project!

Chip caps, too.. maybe slightly over 1 cent.  The 0805 0.1 uF caps I bought a "lifetime" roll of 1000 of them for $20 delivered from China.. they are name brand and are good quality, too.  The "Sure" caps are of OK quality but at low RF levels and low DC levels they are perfectly fine.

 The DigiLite is based on the "Poor Man's DATV" by F4DAY.  The project has been updated for modern computers by using a 2 channel FTDI USB serial port chip (which is the "why didn't I think of it?" part of the design) and a closed-source (unfortunately) DSPic33 and Windows PC software to capture data from a "e-bay special" several year old Hauppage PVR-150, 250, 350 (and probably PVR-USB2) analog capture card.  Which are cheap now (about $30 for US NTSC) on e-bay since they only have analog tuners, and many were pulls from OEM PC equipment.  What is special about them for this project is an Conexant MPEG-2 encoder hardware chip.  Newer computers will soon be able to do MPEG-2 and H.264/AVC MPEG-4 in their CPU hardware, so these older chips for now are the only cheap way of easily and quickly doing digital video for this system.  Actually.. I wish there were hardware H.264 encoders out there for a reasonable amount.. but likely there will not be except for embedded stuff because the PC's will handle it in real time without the ASICs.

The BATC's solution of using an inexpensive PIC and the FTDI serial interface is a maybe slightly kludgy but awfully clever solution of inexpensively and simply pumping data to the QPSK modulator chip.  Coming up with an exact kludge like that kept me from this project for 8+ years.  The only disadvantage to it is that they can only do Symbol Rates (SR) up to about 6250Ksym/s.. but for ham use at this time.. that is more than enough!  It's an awesome start!

The modulation used is DVB-S, which is the older digital standard used by most of the world for satellite transmissions.  I've been playing with LEGAL Free-To-Air satellite for many years.  The majority of what is left unencrypted on C-band and Ku-band FSS satellite is receivable on an inexpensive (from $30 used DVB-S to $130 new DVB-S2 high definition PVR type units) set type box and/or PC receiver card.  This same receiver can take in 950-2150 MHz signals as an IF (with a converter and/or a LNA in front of the IF) in Amateur use.

The disadvantages to DVB-S for ham radio is that it is QPSK with Convolutional Encoding and Reed-Solomon FEC..  Meaning that it's about 3 dB "weaker" than the more "modern" BCH/LPDC codes used in DVB-S2 and that it's QPSK -- optimized for weak signals, but pretty weak when it comes to handling multipath.

Current Analog NTSC AM TV doesn't handle multipath well either ("ghosting").. so those who already do ATV are using Yagi beams other directional antennas for their front-to-back and front-to-side directivity more so than the secondary benefit of gain.  Experiments with DVB-S for terrestrial Amateur TV/Data links show that the same antennas work to fix many of those issues.  Hams will likely use beams at these power levels anyway.

One great advantage to DVB-S for ham use-- and overwhelming one in my opinion is that the bandwidth and data rates, even the video and audio coding the the MPEG-2 Transport streams are pretty much completely up to the link user.  DVB-T in Europe and ATSC in the US is only setup for 6/8 MHz channels and IMHO there is no reason for hams to use this much bandwidth in 2011 for ATV.

Experiments by the BATC and others show that the digital signal is much more usable and stable than equivalent bandwidth analog ATV and it just gets better with reduced bit rates.

They seem to do okay with D1-ish video quality (PAL is 625 lines so it's already "more HD" than NTSC) at 1.5 MBPS-2 MBPS with 1/2 FEC for a net of 1.5 - 2.0 MHz of bandwidth.  I will argue that eventually even this simple modulator could be redone to do the more modern DVB-S2 standard, with more advanced audio codec (more compression) and H.264/AVC type data.  We are not far off of that.  I could see with DVB-S2 and H.264 that 1 MHz wide studio SD (D1) could easily be possible and to boot the C/N ratio to decode these signals can almost be 3 dB less, or even more advanced modulation like 8-PSK could be used to further reduce the bandwidth for a 4dB or so hit over Mpeg-2/DVB-S.  Is it possible for 500 KHz FS video?  Probably but the consumer grade Set-Top-Boxes might not be able to support it.  Most can be coaxed to do 2000 Symbol rate or even 1500... I've heard of some doing 1000.

Ho, Hum?  ATV?  who cares?  Well.. see.. it's not really just that, is it?  The data on DVB-S is transmitted as  as Transport Stream (of 188 byte packets) but there are protocols such as DVB-IP that can do internet over DVB modulation.  There are $20 e-bay boards capable of receiving this as a native computer network interface.  If we can write a data driver to go the other way... half and full duplex multi megabaud links could be done for the price of a Digilite and a TwinHan or SkyStar (or even cheaper like old Broadlogic) DVB-S cards and the supporting RF amplifiers and preamps.  That would have to be a boon for things like emergency communications... and maybe even getting a packet radio network up again.

Oh, and supposedly the newer FET based Mitsubishi power modules seem to be much more linear than the older Mxxxxx series bipolar modules.. so generating a few watts of linear PSK seems to be quite doable for reasonable cost at 70cm (but is it legal in the US?  Our OUTDATED data rules on that band seem to say no even though bandwidth can be reduced by a factor or 6-8 for more reliable digital signals!), 902-928 MHz, 1240-1300 MHz and probably even beyond.

So this is the start of an interesting project for me that I've wanted to do forever.  Hopefully it will turn out well and can be revolutionary.

The bad thing here.. is going back to the rant.. the other project from last year will have to stay in it's current state a little longer.

Summer Blues

Just a quick post to verify that this blog is working.  I can't seem to comment on a comment on another page.

I am going to get back to posting at least once a month here and/or at Amateur Radio.com

Summers are pretty tight for me anyway (I do have a XYL and four young kids remember).. but I had storm damage this summer that also made me go QRT.  I'm starting to catch up.  I"m about at "the end of June" now.

I will be back and the projects that seemingly got abandoned in May will start back up.  Until then... 73