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.  

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

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