Using the RF Power Amplifier of the BITX40 Module

 

PA shematic from the BITX 40 Module

Click on the diagram for a better view

C.F. Rockey W9SCH (who alerted us in SPRAT 22 to the chicken sacrifice option) spoke of transistors that exhibit "quantum mechanical necromancy."  Rockey explained that when this happens, "The transistor simply turns up its toes and dies. Not even an Atomic Physicist can tell you why!"  

This often (very often!) happens with homebrew power amplifiers.  So when we find a good one, many of us stick with it, using the same power amp circuit in rig after rig.  I have done this with the power amplifier from the BITX40 Module. 

Mythbuster (75 & 20 Meter) version (early)  

Click on image for a better view. 

https://soldersmoke.blogspot.com/2021/08/mythbuster-video-13-rf-power-amplifier.html

Same amplifier built into Version 2 of the 15-10 Transceiver 

Click on image for a better view. 

In the build for the 15-10 transceiver you can see some changes.  I used an RD06HHF1 instead of an IRF-510.  I used an 8.1 volt zener diode instead of the regulator chip. I set the bias at around 5.5 volts DC on the gate of the RD06.   I used a smaller, metal can driver transistor (it works fine). I changed the input/output physical configuration between the pre-driver and the driver stages (I think it was kind of goofy the way I had it in the Mythbuster).  Finally, you can see how I used a small piece of copper tape (with conductive adhesive) to shield the line going from the driver transformer to the gate of the RD06.  The wire was too small to use a bit of shielded coax, but I think the copper tape and the copper clad board beneath it work just as well. 

Farhan provided me with some fascinating background on this circuit: 

Bill,

I just saw your post on the bitx40 power amp. The credit must go to Wes for this, it is from the Lichen transceiver described in 6.9 of the EMRFD. I merely copied it with some modifications for it to work with junkbox components.

It bears mentioning that at that time I didn't have a way of generating two tone signal or measuring the IMDR. Those came later when I built my own spectrum analyzer based on Wes and Terry White's spectrum analyzer. It was sheer luck that I picked this power chain that already had careful gain distribution.

For the output, the original build used and LPF with inductors wound on a ballpen shell and TV baluns cores instead of toroids. Again, it was incredibly lucky that they worked at all. 

- f

SolderSmoke Podcast #243 -- HI7/N2CQR, uBITX mods for 10 meters, High-School Direct Conversion Receiver Project Launched (Success!) Mailbag

 

DC RX and one of the PTO boards we built as demos last night. 

February 10, 2023

SolderSmoke Podcast #224 is available. 

http://soldersmoke.com/soldersmoke243.mp3

Video here: (32) SolderSmoke Podcast 243 (video) Hi7/N2CQR, uBITX, Success with High School Receiver Project - YouTube

Pete N6QW had technical difficulties this morning.  He insisted that the show must go on.  Pete will be back for the next episode. 

 

Travelogue: 

Bill in the Dominican Republic for all of January.  

HI7/N2CQR  Eastern tip of the island. uBITX and dipoles. 

20, 17, 10.  CW and SSB.  SSB was tough and I had reports of RF getting into the signal.

Went to CW. 

Worked VWS Mike KA4CDN, and Walter KA4KXX on 20CW.

Finally moved up to 10 CW.  Lots of contacts. Even though uBITX very QRP on ten.

I am modifying the uBITX now.  

Copper tape shielding to keep RF out.

 Low power out not the fault of the IRF-510s.  The problem is the 2N3904s.

Will replace with 2N2222 in To-18 cans.

Dean KK4DAS putting KD8CEC software into Arduino.  I gave up.

Who sent me this orphan uBITX?

SolderSmoke Shack South in final phase of construction.

 

SHAMELESS COMMERCE DIVISION:

Patreon!

Bezos Shopping!

 

DC Receiver Project

Local High School radio club. 

Simple:  Like Herring Aid 5 and Wes’s original.

Farhan’s four stages:

BP Filter, Diode Ring, PTO, AF amp. 

Simple Colpitts PTO SURPRISINGLY STABLE.

Simple and easy.  No chips.  No complicated circuits.

Guys have helped test out the design:  Rick N3FJZ, Walter KA4KXX,

Daniel VE5DLD, Stephen VK2BLQ and others. 

First session last night:  We demonstrated build of the PTOs.  

They worked (thank God).

 

Open Circuits book.

Envelope Detection Controversy

Save the Antenna – Book “Losing the Nobel Prize” K1JT

 

MAILBAG

--Dean KK4DAS 10 meter DSB!  Tiny SA ULTRA! FB

--John AC2RL on Elmer W3PHL DSB guy

--AC3K reports inventor of Fender Stratocaster guitar was a ham: W6DOE

--AF8E was doing POTA.  I worked him. He said my rig had presence. FB

--Alain F4IET FB DSB rig with mic in Cigar can!

--Daryl N0DP worked him on SSB.  He is homebrewing

--Steve N8NM was in for repairs but is on the mend.

--Rick G6AKG working with sub-harmonic mixers and logic chips

--Paul HS0ZLQ Built DC receiver but looking for something else to build. No DSB!

--Steve AB4I – Coherer, Jagadish Chandra Bose, and Marconi

--Eldon KC5U    Worked VK5QD right after me and mentioned SolderSmoke FB

--Todd K7TFC is building the DC RX.

--Tony G4WIF and Ian G3ROO using automotive relays for antenna switching. FB.

--Dave WA1LBP Great to hear from my fellow Hambassador (Okinawa)

Older post comments:

--Scott VO1DR was also in CF Rockey’s class! (Blog comment)

--Aurora Aug 4, 1972: Twelve people shared memories.  (Blog comment)

--Will WN1SLG Googled novice call and was led to my Novice log.(Blog comment)

SolderSmoke Podcast #238 -- SolderSmoke Shack South, Cycle 25, Chiquita Banana Radio, RCA, HQ-100, Mate Mighty Midget, Sony SWL RX , Mailbag

SolderSmoke Podcast #238 is available:  http://soldersmoke.com/soldersmoke238.mp3

TRAVELOGUE:  

Cathartic decluttering:  Bill preparing for future winter travel to Dominican Republic.  Will build SolderSmoke Shack South.  Dividing everything up:  Rigs, parts, tools, supplies, antennas, test gear.  Everything.  

OUR SPONSOR:  Parts Candy.  

https://www.ebay.com/usr/partscandy  Premium quality test leads! Hand cut, hand crimped, hand soldered, these will become your new favorite test leads GUARANTEED!

PETE'S BENCH:

-- Cycle 25 better? – Out here on the left coast – it is not evident

-- Chiquita Banana and the US Navy in early ‘wireless” operations.  Why RCA was created by the US Navy in 1919.

-- Update on the MAX2870 –someone has written the code to make it work with the Raspberry Pi and the QUISK SDR software

-- Field Day prep

SHAMELESS COMMERCE DIVISION:

 

Bill needs your help:  

-- Please watch his YouTube videos.  The longer the better!  Success based on hours watched. Great to have on while you are working in the shack. Just go to YouTube and search for the SolderSmoke channel. Or:  SolderSmoke - YouTube

-- Please put links to the SolderSmoke blog on your websites and blogs. 

-- How to USE the SolderSmoke Blog: Propagation, shopping, other sites... 

-- Please put comments under the articles on the SolderSmoke blog.  We like comments and dialogue. 

BILL'S BENCH:

-- Repair of the Sony ICF SW1 shortwave receiver.  Bad electrolytics.  Number Station receiving device? 

-- HQ-100   Q-Multiplier. BFO Switch. AVC.  Noise Limiter limitations.  Dave K8WPE: Old Radio Lessons.

-- MMMRX: Detector circuit. Alignment. Muting. On the air (40 AM with DX-100) 

MAILBAG: 

-- Bob Crane W8SX -- Great interviews at FDIM. On the SolderSmoke Blog. Thanks Bob! 

-- Dave Bamford W2DAB -- Stickers on the Upper East Side of Manhattan.  FB Dave! 

-- Farhan VU2ESE:  LADPAC software now available through W7ZOI' site.  

-- Lex PH2LB: Stickers in a Netherlands pub.  

-- Dave K8WPE Michigan Mighty Mite links.  Old Smoke idea. On the SolderSmoke blog. 

-- Rich WB4TLM was in the electronics class of CF Rockey W9SCH. FB. 

-- Dean KK4DAS Working on  his dad's HQ-170A. VWS maker group on mixers. 

-- Grayson KJ7UM -- Mixology article in ER. 

-- Pete Eaton -- Farhan's new analog rig: Daylight again!  Standby for more info from Farhan. 

-- Will KI4POV New HB Al Fresco single conversion superhet.  FB. 

-- Alvin N5VZH. Shep's "I Libertine."  Yes.  I laughed, I cried,  It changed me. 

-- Chuck KF8TI.  Mr. Wizard!  

-- Steve N8NM on the mend after some routine maintenance. 

-- Ben AB4EN is listening and likes the podcast -- Thanks Ben. 

May 1939 QST

"Dream It - Make It" -- Rich WB4TLM, Mrs. Filoramo, and C.F. Rockey W9SCH (aka The Rock)

 

Rich WB4TLM spotted my bog posts about famed QRPer C.F. Rockey W9SCH.  He followed up by sending me a link to the WB4TLM blog.   It is a lot of fun.  It describes his troubles in school and his subsequent participation in The Rock's electronics class. 

Rich's blog has some great inspirational quotes for ham radio homebrewers.  He is now teaching at Full Sail University. Their fabrication lab has a motto: "Dream it -- Make it."  And in a quote that made me think of my good friend Pete Juliano, Rich tells his internet-jaded students, "I've been there...done that... I can get you there faster." FB OM.  

Here is the link to Rich's blog:  http://richardarndt.com/about

Thanks Rich.  And thanks to Mrs. Filoramo and The Rock! 

Rich WB4TLM

From a Student of C.F. Rockey, W9SCH

C.F. Rockey W9SCH

We have discussed the monumental work of C.F. Rockey, W9SCH, SK before.  Yesterday a comment appeared under that post that is just too good to leave buried in the comments.  It appears below.   Jeff's comment also caused me to dig up my small collection of "The Five-Watter" issues from the Michigan QRP Club.  Rockey wrote a column for that magazine.  It contains a lot of tribal knowledge.  Here is Jeff's look back:  


This turned up for me in a Google search for "Charles Rockey QRP ARRL" during a phone call with a friend of mine who was bemoaning that he never got a novice license because he could not master Morse code (he is in his mid-60s, as am I). I was taken back to the communications electronics class I had my freshman year at New Trier East in Winnetka (not Wilmette) IL in 1971. That class was taught by none other than C.F. Rockey, known to us students as The Rock. I think about him fairly often because I grew up to become a very hands-on engineer and can recall parts of his class quite clearly, even at this remove. Somewhere I still have the reports we had to write (typed on a typewriter) each week. He was a huge influence on me and I was saddened to have his passing undeniably confirmed for me. I have the little chemistry book he authored beside me now *Electrons, Atoms and The World* and am glad to be able to read his obit. One thing needs to be added to it: He won the ARRL 5000 mile-per-watt award for working Anzio, Italy from his home north of Chicago on 5W. I am very lucky to have had him as a teacher and mentor for those years. Thanks for sharing. Cheers, Jeff Mizener, DFW-TX

Dead Chickens and Fake Transistors in Medellin Colombia: HK4DEI's Micro 40 DSB Rig

Daniel HK4DEI wrote to report that page 149 of the SolderSmoke book was providing some solace and comfort as he struggled to get his version of Peter Parker's Micro 40 Double Sideband rig going.  He was having problems with the amplifier.   He was almost at the point of sacrificing chickens to Papa Legba.  I wished him luck and told him to hang in there. 

Elisa saw my e-mail to Daniel and complained that I hadn't given him the solution to his amplifier woes.  I tried to explain to her that there are sometimes things in this universe that are just UNKNOWABLE.  C.F. Rockey W9SCH (who alerted us in SPRAT 22 to the chicken sacrifice option) spoke of transistors that exhibit "quantum mechanical necromancy."  Rockey explained that when this happens, "The transistor simply turns up its toes and dies. Not even an Atomic Physicist can tell you why!"  

But Daniel persisted.  And he won the battle:

Hey Bill

Did you kill some chickens already? If you did, THANK YOU!  If you don't, then please enjoy a nice sancocho de gallina for me.

But seriously... guess what?

FAKE TRANSISTORS!!!!

I knew I couldn't be screwing everything up so badly and VK3YE's circuit couldn't be so wrong.

I was getting nuts trying to understand why it wasn't working, changing a single inductor could fry the final instantly or not getting any power out at all (?) also my final BD139 was getting extremely hot, and many of them died with no apparent reason (Page 149!!!!).

I ordered a "good" deal of BD139's and BD140's combo for an incredible low price from [A WEB SITE], I've ordered many *apparently good components from that site with no problems so far... mainly resistors and capacitors. Having tried everything to get my circuit working and after some quick online search about fake transistors from china my suspicions grew considerably and I remembered some -other- BD139's I had ordered from Amazon some time ago.

I proceeded to solder the new transistors in place in my PA and Bingo! No more heating of the final and about the expected 0.5W out from my first DSB homebrew rig. I quickly reported to a fellow homebrewer in a local net and the report was amazing! 59 +10, the final transistor was comfortably warm to the touch and my mind could finally rest... lesson learned! What an electromagnetic achievement!

Just wanted to share my success Bill and thank you again for you book and you kind response.

Please say hi to Elisa and the Cristalinhos from a fellow Latin friend.

Clear Skies.

73/72 from Colombia!

Daniel

HK4DEI

SolderSmoke Podcast #149

Podcast #149 is now available:  http://soldersmoke.com/soldersmoke149.mp3

17 February 2012

IGY intro
Cappuccio turns off TV on New Year's Eve
Pre-inaugural day on the National Mall
The importance of audio bandwidth in DSB rigs
On 15 meters with the HT-37 and the Drake 2B
Q Killing and Swamping
Adding a Filter the Mighty Midget Receiver
Italian lessons via Echolink
Billy and the Raspberry Pi -- Three Cheers for Ada Fruit
Translate Button on the Blog page (upper right)
C.F Rockey SK
Mailbag: Kludge or Klooge?  

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

C.F. Rockey, W9SCH, Homebrew Hero, SK

In podcast # 148 I recounted how I had turned to one of his articles, "Prolegomena for QRP Transmitters" for inspiration.   Just Monday Brian,  N1FIY,  e-mailed asking for info on how to find the article.  Today, Mikey,  WB8ICN,  let me know that on December 23, 2012,  QRP Hall of Famer C.F. Rockey,  W9SCH, had become a Silent Key.  

I've been a big fan of Rockey's writing and projects for a long time.  I was sad to hear that he had passed away, but I know that through his writing his influence will be felt in workshops and on the airwaves for a long time to come.  

Here's a sample of Rockey's writing:  http://n4trb.com/AmateurRadio/QRPp_Vol01_No03.pdf

Here's Rockey's obit:


Charles Franklin "Rock" Rockey, Jr.,
Whitewater, WI (1918 - 2012)
June 21, 1918 - December 23,2012
Charles Franklin Rockey, Jr., known as "Rock", age 94, of Whitewater, died on Sunday,
Dec. 23, 2012, at Fairhaven in Whitewater. Rock was born in Oak Park, IL, on June 21,
1918, the son of Dr. Charles F. and Ada (Nichols) Rockey. At an early age, he became
interested in ham radio, earning his amateur radio license at age 16. Operating as W9SCH
for more than seventy years, he made contact with ham radio operators all around the world. In 1996, he
was inducted into the QRP Hall of Fame. Rock graduated from Oak Park-River Forest High School in
1937. He enrolled in Elmhurst College, but interrupted his studies in 1942 by enlisting in the U. S.
Navy. He served as an aviation electronic technician in Port Lyautey, French Morocco, and in Naples,
Italy. After World War II, he returned to Elmhurst College, graduating in 1947.
Rock worked at Walhenius Institute instructing brew masters, then in the early 1950's, taught at
Milwaukee School of Engineering. From 1955-1979, he taught chemistry, physics and electronics at
New Trier High School in Wilmette, IL. He was also the faculty sponsor of the student radio station
WNTH.
On retirement, Rock and his wife (the late Frances) moved from Deerfield, IL, to Albany WI. Rock
became friends with the local farmers in Green County as a milk tester for the Wisconsin Dairy Herd
Improvement Association. In addition to contributing many articles to radio and scientific magazines,
Rock wrote two books: "Electrons, Atoms, and the World: Chemistry for the Young in Heart" and
"Secrets of Homebuilt Regenerative Receivers." He greatly enjoyed playing polkas on the accordion.
Rock is survived by his son, Joseph (Jane) of Highwood, IL; and two grandsons, Jonathan (Meghan) of
New York City, and William (Alexandria) of Esparto, CA.
A Memorial Service was held at Fairhaven in Whitewater. Memorial contributions are requested to
Fairhaven Senior Community, 435 Starin Road, Whitewater, WI 53190.



Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Ham Radio Exam Day in Ireland: October 4

OK gang, it is time for us to do what we can to help a worthy Short Wave Listener transition into the world of amateur radio.  Chris will be facing the Irish radio examiners on October 4.  So please try to send some positive vibes in the direction of Ireland.  Cross your fingers (especially the ones with the soldering iron scars!)  Maybe melt some sacrificial solder. C.F. Rockey might suggest sacrificing a chicken to Papa Legba.   Say a prayer if you are so inclined.   Good luck Chris!  

Hi Bill,

Just wanted to say thanks for the great podcast and keep up the good work.

I’ve been listening for a good while now and following your subscriptions advice on things like Tim’s “Hot Iron” Constructors club and QRP/Sprat magazine.

I’ve got my Amateur Radio licence test in 2 days time (4^th Oct) over here in Ireland (Dublin’s Comreg Offices) so please give all the candidates a mention and wish us luck.

Great book as well…  When I’ve had my fill of studying I switch over to your book for a while to relax a bit and read your thoughts on getting to grips with it all.

There’s only one licence here in Ireland so it’s Full or nothing  so it’s going to be tough! My brain is well and truly fried!!

I’m determined not to be a (can’t even remember what you call them in your book ha ha) “User” and go out and buy everything I need so I’m looking forward to lots of construction projects when (IF!) I get my licence J

Best Regards (I don’t think I’ve earned my right to use 73’s yet),

Chris

(EI1628 SWL/qrz.com)

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20