Amplifier Woes! Instability at Low Drive Levels! (Video)

I have to keep reminding myself:  This is not "plug and play." These are not appliances. 

After I got my 40 meter problems squared away,  I was doing some testing on my beloved 17 meter BITX.   I noticed something weird:   With the CCI EB63A amp feeding my 17 meter Moxon antenna, as I raised the output of the BITX17 driver, at one point (at about half the max input power) the SWR would suddenly spike. Then, as I raised the drive level above that point, the SWR would go back to normal. 

I looked at it on the 'scope.   I can see the signal go very ugly at the mid-level drive point.  In the FFT display, I can see that there is a strong signal at around 435 kHz.  The 18 MHz signal seems to be riding along on top of it.  Take a look at the video above.

Additional clues: 

I see no signs of the 435 kHz signal at the output of the BITX 17.  It seems quite clean.

This problem disappears if I replace the Moxon with a dummy load. 

This problem does not show up if I feed the EB63A with my almost identical BITX20.   And I use the same LP filter on both 20 and 17 in the CCI amp.

Any suggestions?  Has anyone had this kind of problem? 

Allison and Pete have been helping me with this.  Thanks to both of them.  

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The 1Watter

There are currently only 2 in the universe.  And they have been talking to each other.  Soon there will be more.  Many more.

http://www.kitsandparts.com/1watter.php

http://www.1watters.com/

http://www.k7qo.net/onewatter.html

Chuck Adams explains (via the qrp-tech mailing list):
 

Aug 3 at 7:07 PM

 

Gang,

I and Diz have been playing on 20m with 1W.
OK, I've been playing. Diz has been working night
and day.

He has a kit coming out in two weeks or so. Don't rush
him. 

He has S/N 0001 and I have S/N 0002. These are the
only two 1Ws in the Universe. Yesterday (local time)
but 0000UTC today, I went to the lab to put a WWV
atomic clock above the desk for logging purposes.
I turned on the rig to listen while I put the screw into
the side of the shelf to hang the clock on. No warmup
drift. I'm tuned to 14.059MHz, the freq both Diz I start
out on and low and behold I hear him calling CQ. I pound
the paddle to call him and he went back to AF5XF in NTX.
Darn.

At 0031UTC I call him and I get a 229 and later a 339 and
he was a 539 here in AZ. So all the 1Ws in the Universe
have talked to each other. :-) The race is on, when and if
you get one to work us all. Or work us with the rig of your
choice and the power level of your choice....

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

Amateurs and the Search for Extra-Terrestrial Intelligence

Interesting article.   The author mentions a connection between SETI and the Homebrew Computer Club:

http://motherboard.vice.com/read/aliens-in-the-backyard-how-amateur-astronomers-will-help-find-et

We had a SolderSmoke "SETI at Home" team.  Anybody know how are we doing?   

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

Video of Curiously Strong Altoids Tin Frequency Counter

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

Pete is Having Antenna Project Problems -- Can you Help?

Our friend Pete, N6QW, has run into some difficulties in his antenna project.   The push-up/tilt-over mast he is working with doesn't seem to be up to the task.  Just look at what this is doing to him!  

Does anyone out there have suggestions on how Pete might easily get his 2 element beam up to about 30 feet without spending kilo-bucks?

The project is described on Pete's blog:

http://n6qw.blogspot.com/

You could leave suggestions or ideas on Pete's blog, or in the comments section here, or e-mail them to soldersmoke@yahoo.com

Thanks.

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

An Earlier Use of "Basta!" (MUCH earlier)

It turns out that Pete and I may not be the first homebrewers to make use of the word "basta!"  At lunch time, while sitting near the Einstein memorial in Washington, I found a short article in SPRAT 83 (Summer 1995).  In it, Robert PA3BHK presented some ideas for reverse polarity protection, and noted that his friend Peter PE1MHO had discovered an interesting phrase from antiquity:

"SPIRITUS TRANSISTOR BASTA"

According to Peter this was the diagnosis of a classical Roman engineer when checking a transistorized PA that went dead after an accidental reversal of the polarity of its supply. Above we see that same engineer, obviously setting up a 2 meter Moxon.  

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

Pete Noodles a New Antenna

Big doings at the Newbury Park Lab of N6QW.  A new antenna is in the works.  Lots of noodling underway.   Much tribal knowledge is being dispensed (FREE!) via Pete's blog:

http://n6qw.blogspot.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

A "Curiously Strong" Frequency Counter

I got a six digit San Jian frequency counter for use with my BITX20.  I was trying to figure out how to put it in a box and mount it on the rig when I realized that the counter fits almost perfectly in an Altoids tin.  THE RADIO GODS HAVE SPOKEN. 

I found the counter on Amazon.  I use an eight digit version with my BITX17.  But I think the six digit version is better (it fits in an Altoids tin!)

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

Pete has a Blog!

Check out the new blog from Pete, N6QW.   We hope he continues to post.   Please link to his blog and help spread the word.    Here it is:

http://n6qw.blogspot.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

Mikele's Croatian Belthorn Transceiver

Mikele's rig is a real "International Brotherhood of Electronic Wizards" kind of project.   The Belthorn design is out of England.  N6QW has added a lot of California influence.  The Nokia screen adds a bit of Finland.  And of course Mikele's excellent construction makes this a profoundly Croatian rig.

We love seeing rigs in their "out in the open " phase.   Thanks Mikele!  


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

Dongle Update -- Dongles, FUNcubes, Meteors, QRP, and SPRAT

Hi Bill, Pete,

Ken Marshall G4IIB here the guy that wrote the SDR Primer in Sprat 162. I have been listening to your excellent podcasts. You guys cover a lot of ground in the May issue and touched on to the SDR dongle, its potential for future developments etc. I noted that you where going to buy another to cover VHF. Well if it ain't too late consider this New version by Newsky they are already getting difficult to get a hold of and are only available in the USA. It uses an R820T2 tuner (better LNA) an upgraded and stable crystal oscillator, a reinforced antenna coax and socket. The one I managed to get hold of also had a modified PCB with solder pads for the the Q channel (pins 4&5) to connect the toroid. Incredable at 22 of your Bucks. See the pictures and read all about it on amazon.com.

http://www.amazon.com/gp/product/B00QFCNNV0/ref=as_li_tl?ie=UTF8&camp=1789&creative=390957&creativeASIN=B00QFCNNV0&linkCode=as2&tag=rsv0f-20&linkId=VNHED72IVHA5O2KT

All we need is for them to slot a 12 or 16 bit ADC in and we could have a truly great SDR receiver.

I noticed in your podcast you mentioned radio astronomy and satellite reception. Ironicaly back in 2013 this is how I started with SDR dongles. I read an aticle on the web on meteor scatter and started experementing with a dongle. Meteor scatter hunting is a bit like watching paint dry unless there is a known storm. So this led me on to the Funcube satellites. The signals from which although QRP 200mW are very stong and you can receive them on almost any antenna. The funcube dashboard software is available for free from AMSAT and alows you to download telemetry. You can also listen to amateur SSB an CW transmissions. There are lots of satellite tracking software available too. This then led onto weather satelite picture reception I built a 4 ele turnstile antenna for this but I found that I needed an LNA for reception at my location. I then started to listen to the amateur bands. Like you Bill I became interested in radio at the age of 11 and got licensed in the early 70's but work commitments  meant I had a 30 year absence from Ham Radio until I stumbled on these SDR Dongles. They got me back into the hobby and I joined the GQRP Club. I noticed that almost no one in the QRP fraternity was talking about RTL SDR hence I started writing the Primer  and submitted it to George in late 2014 for publication in Sprat. As you know it appeared in the Spring Sprat and seems to have generated lots and lots of interest in the QRP community. I am delighted by this response and look forward to lots more interesting articles and podcasts. Have fun with your dongle.

Ken G4IIB

PS I wrote another article on getting these dongles to work under Linux. Linux uses completely different architecture so that the software used is completely different to windows. I notice that the software I use for Linux is also available on Mac OS which uses similar architecture (UNIX) so in theory it should also work on a Mac. Quite a few people have expressed an interest in getting a dongle to work on a Mac. As I do not poses a Mac I have not tried this out.

Funcube Dashboard

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Ham Radio on the Kon-Tiki

Hi Bill

Just found a short Youtube QRP video which is quite fun. It's of the radio side of  Thor Heyerdahl's cross-Pacific Kon-Tiki raft expedition in 1947, operating /MM with 7 watts. I found a longer description of what they had and what they did - including a thrilling tale of drying components on coral reefs while they desperately tried to make contact having washed up on an island - but not of the unusual parrot incident with a hydrogen balloon-lofted antenna during the voyage. That's only in the video.

 

It's all gripping adventure radio stuff, and shows what HF and a bunch of tubes could do before the digital satcom age.

 

The video's here - https://www.youtube.com/watch?v=qEvM4HxQxSQ

and the write-up (excerpted below) is here - http://www.arrl.org/news/last-surviving-crew-member-of-i-kon-tiki-i-expedition-passes-away

 

"The expedition used call sign LI2B and carried three watertight radio transmitters. The first operated on the 40 and 20 meters, the second on 10 meters and the third on 6 meters. Each unit was made up entirely of 2E30 vacuum tubes providing 10 W of RF input. As an emergency backup, they also carried a German Mark V transceiver originally re-created by Britain's Special Operations Executive in 1942. Other equipment included a hand-cranked emergency set of the Gibson Girl type for use on the maritime bands, a special VHF set for contacting aircraft and two British Mark II transmitters. The Kon-Tiki also carried a National Radio Company NC-173 receiver. Dry batteries and a hand-cranked generator supplied the power."

73s

Rupert, G6HVY

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