Color Code Violation -- Almost as Bad as Breaking Ohm's Law!

A cautionary tale:   How would you read the color code on that little resistor?    It was plucked from a strip marked 2.2 ohms.   And indeed it is red-red-gold.  2.2 ohms, right?   But no,  my friends. On the DVM it reads 2.2 kilo ohms.  2200 ohms.  Believe me, that makes a big difference when it is in the Vcc line of your driver!  It took me a while to find out WHY that driver wasn't driving very well.  

This turned out to be one of those very satisfying trouble-shoots --  the problem was elusive and it wasn't all my fault.  But I should have MEASURED the resistor value before soldering it in. 

Here is the scary part:  The next resistor from the same strip was marked the same way, but measured 2.2 ohms.  Be careful out there. 

How LCD Displays Work (Video)

8 Bit Guy does a great job de-mystifying the LCD displays that we have been using.

An Old but Cool DiFX: The Epiphyte

I've been hearing about this rig for many years.   It first appeared in the September 1994 issue of QRPp, the journal of the NORCAL QRP club. A condensed version of that article appeared in SPRAT 81 (Winter 94-95). The designer is Derry Spittle VE7QK from Vancouver, British Columbia.

The name always puzzled me.  Here is the explanation:  It started with the Neophyte: A very simple direct conversion receiver that many of us built.  The Neophyte was mostly an NE602 and an LM386.  In the Epiphyte, a crystal filter and a second NE602 were added, turning the Neophytes into a superhet receiver and -- with some additional circuitry -- an SSB transceiver.  The Oxford English Dictionary reportedly defines an Epiphyte as "a plant that grows on another plant"(see picture below).   The Epiphyte grew out of the Neophyte.

And this plant grew in British Columbia, which seems -- like Australia and New Zealand -- to be fertile ground for simple phone rigs.  I'm pretty sure the "Wee Willy" DSB rig also came out of BC, and it may have had a similar purpose:   allowing for portable contact with the BC Public Service Net on 75 Meters.  

There are many features of the Epiphyte that I like:  There is a simple 455 kHz filter and a ceramic resonator BFO/Carrier oscillator. The original design featured a VXO-like circuit using a ceramic resonator at 4.19 MHz.  And it ran off AA batteries (as did the NE602 DSB rig I took to the Dominican Republic).

Unlike my NE602 rig, the Epiphyte made an artful use of the fact that NE602's can be set up to have TWO inputs and TWO outputs.  Where I used DPDT relays to switch inputs and outputs from both NE602s,  OM Spittle left all the inputs and outputs connected, and simply switched the VFO and BFO signals.  Ingenious.  

There were updates and improvements.  The Epiphyte 2 and 3 featured increased power out (5 watts vs. 1 Watt).  Version 3 has an IRF-510 in the final, driven by a CA3020A chip.  That chip is capable of 70 db gain.  Wow. 

In 1996 NORCAL and G-QRP donated 50 EP-2 kits to radio amateurs in third world countries. Very nice.

In 2000 NORCAL did a kit of the EP-3 -- it sold out in 24 hours.  Here is a nice article on the EP-3:
http://www.norcalqrp.org/files/Epiphyte3Mnl.pdf

And above we have a video from Japan of an EP-3 in action.

Video (Audio) of N2CQR (me) on 40 Meters with BITX DIGI-TIA

This was the icing on the cake.  Ruben AC2RJ up in New York was monitoring as I called CQ with my BITX Digi-Tia last night on 40 meters.  He recorded the contacts that ensued.  I was really glad that he recorded VE3XBO describing his experiences with a BITX 40 Module at his local radio club -- The WAX Group of the Barrie Radio Club in Ontario. 

Farhan's module is really starting to show up more often on the band. On the 19th of April I talked to Bruce KC1FSZ -- he was on his Peppermint Bark BITX 40.  And on March 30 I talked to Josh KE8CPD on his BITX 40.

Click on the arrow (above) to listen to Ruben's recording.  Ruben has a nice YouTube channel here:
https://www.youtube.com/channel/UCXClX_GBzFQIiqTwgnt8qxA

DiFX! My New NE602 Rig is On the Air

Pete would call this a DiFX:  a transceiver that is Different from a BITX.  This started with my effort to get an Si5351 working with a little 1 inch square OLED screen.  Tom Hall AK2B helped me with the software (thanks Tom). Once I got that done, I figured I could build a simple receiver with a homebrew 11 MHz crystal filter, two NE602 chips, and an LM386 AF amplifier.  That was working great, then Pete told me to turn it into a transceiver.  I used some of Pete's boards (thanks Pete).  

The Epiphyte transceivers also use two NE602's, but they ingeniously switch the BFO and VFO between the two chips.  I didn't switch the oscillators -- instead I switched the inputs and outputs of the two chips using two DPDT relays (thanks Jim).  A third DPDT relay switches the antenna between T and R, and turns on and off the PA stage and the AF amplifier.

This is a DIFX, but there is some BITX circuitry in there.  The power amplifier stages are right out of the BITX Module, as is the AF amplifier (thank again Farhan).

The only real problem I ran into had to do with the very low power out of the NE602 VFO mixer on transmit and the impedance matching between the NE602 and the PA chain.  I had to increase the gain on the first RF amp (pre-driver) using ideas from Steve Weber's 40 meter SSB CW QST contest rig (thanks Steve).  I experimented with various connections between the NE602 and the BP filter.  Finally I got it going.

The heat sink on this one is different too:  it is just the chassis.   The IRF 510 is bolted (insulated) to the aluminum box.

I fired it up this afternoon and in spite of horrible conditions on 40, quickly had a nice rag chew with KJ4ZMV in Indiana.  I haven't even built a mic amp yet!  I am running the D-104 right into the NE602 balance modulator.  There are no signs of unwanted modulation or spurs.

FB!   TRGHS!   VIVE LA DIFFERENCE!

  

VFO Tribal Design Wisdom from Joseph Carr K4IPV (SK)

I had in my files somewhere this great article by Joseph Carr K4IPV about the design of ham band VFOs, but then I lost it.  Yesterday I found it, but the paper copy was in bad shape.  Internet to the rescue!  Here it is.  Go to page 79.  
http://www.americanradiohistory.com/Archive-Poptronics/90s/93/PE-1993-07.pdf

There is a follow-up article the following month, on page 78:
http://www.americanradiohistory.com/Archive-Poptronics/90s/93/PE-1993-08.pdf

Something I heard on 75 meter AM this morning may have gotten me thinking about VFOs: I hear that International Crystals is going out of business.  That might be the last manufacturer willing to make bespoke crystals.   If that is true, that has big implications for homebrewers.   We will now have to build stable VFOs or succumb to the siren song of the digi synthesizers.  "L and C FOREVER!"

Joe Carr K4IPV mad so many contributions to the radio art.   I have several of his books.  He had a real talent for explaining circuits.  Sadly, I find very little information about him on the internet.  I know he lived in the same Virginia town that I live in.  Does anyone know anything else about Joe Carr? 
http://forums.qrz.com/index.php?threads/joseph-carr-ki4pv-silent-key.50027/

HB2HB! BITX40-BITX40 with KC1FSZ

This was very cool.  I got on 40 SSB this afternoon with my trusty Digi-Tia.  I heard a station saying he was running 5 watts... Hmm, could that be a BITX40?  Indeed it was.  And it was the Peppermint Bark BITX 40 of Bruce KC1FSZ that we featured a few weeks ago.   He was up in Boston.  K3MY was kind enough to let us have the frequency.  Bruce and I had a nice contact.  He told me he is working on a completely scratch-built BITX.  FB.  TRGHS.   

Pete Juliano's Expulsion from the QRP Hall of Fame

First, I'd like to thank the many, many radio amateurs who sent in e-mails demanding that our friend Pete Juliano stay in the QRP Hall of Fame.  Their outrage at his expulsion was palpable.  They were angry and fired up.  Many compared Pete Juliano to baseball great  Pete Rose (who also got expelled from a Hall of Fame).   They wrote to us from all around the globe.  Several saw the action against Pete as yet another example of the deep divisions that are affecting modern society -- several saw it as being connected to our recent Presidential election, and/or BREXIT. 

Some writers took a diplomatic approach and tried to suggest ways that this ugly conflict might be ended -- one fellow suggested that Pete try to redeem himself by agreeing to enter some kind of QRP 12 Step Program.  Others got legalistically combative and said we should just "lawyer-up."

A number of our correspondents took note of the seasonal nature of these kinds of events. Who can forget the April  move a few years back by the New Jersey State Legislature to ban the use of soldering irons in the home?   "This kind of thing always seems to happen in the Spring-time!" said one irate Juliano surrogate,  "It is like Shakespeare wrote:  'Beware the Ides of March' -- only two weeks later!" Another ham also spotted the seasonal nature of these stories and quoted from T.S. Elliott's poem "The Wasteland":  "April is the cruelest month, especially the first day!"

We must point out that not all those who wrote were opposed to Pete's expulsion -- one writer said, "It is about time that that Pete "KW" Juliano got what he deserved! Good riddance!" (We have sent this e-mail to one of Pete's Italian-American relatives in New Jersey for, uh, action.)

Several of those who wrote in support of Pete are prominent members of the amateur radio community (they will -- if they follow our instructions -- remain anonymous.)

One activist supporter said that Pete's expulsion should lead to a street protest movement called "Pete's Award Matters" and that the chant at demonstrations could be "NO JULIANO, NO PEACE!"  Kind of catchy don't you think?

Anyway, we sincerely hope you have ALL figured out what was going on here. For those who have not, and for all those who wrote in, let me complete the tradition by saying it: "April Fool!"   

We'd like to thank all who participated in this long-standing amateur radio tradition.  Special thanks to Preston Douglas and the QRP-ARCI for putting up with all this.  (Tony Fishpool told us that he knew this couldn't be real, because someone as nice as Preston Douglas would NEVER expel anyone.)     

Micro-Shocks (and QRP Power?) from Nearby High Voltage Lines (video)

I spotted this on Hack-A-Day.  It caught my attention because many time, while riding my bike along the Washington and Old Dominion bike path, I have felt electrical shocks from the handlebars. 
Now, before you all conclude that OM Bill is losing it and start suggesting that I wear an aluminum foil hat, realize that the bike path is directly under some seriously high voltage power lines.  And that esteemed UK newspaper "The Daily Mail"  confirms that these shocks are, as the kids say, a thing.
http://www.dailymail.co.uk/news/article-2655190/Cyclist-told-grab-metal-bike-time-rides-overhead-power-line-gives-ELECTRIC-SHOCK.html
So think these Russian dudes are onto something.  How long will it be before the QRP community starts exploiting this power source?   (Please be careful about where you put the antenna!)

Another Thermatron Receiver (video)

Thanks to Steve N8NM for sending this along.   He said it seems to be crying out for a synthesized VFO -- I disagree,of course. 

I like the filter arrangement -- one crystal at 455 kHz,  two tune-able IF cans and a phasing control.  This seems like a good way to get both AM selectivity (broad) while still having the ability to narrow the bandpass for SSB. 

The builder did a great job. Does anyone know who he is?