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Thursday, June 29, 2017

Smoke Test Failure!


This is why you need fuses!  And reverse polarity protection!  Yikes! 

The Workshop at AA8V

Field Day was a big success for me this year.  I was in category "1E" which meant that I was home in the air conditioning, but doing my bit for emergency service by using a gel cell as my power source.  A SOLAR CHARGED gel cell.  So don't anyone call me a slacker, OK?

I was on my HW-8 and made a total of two contacts.  The second was with AH6AX.  I wasn't fooled -- I knew they weren't in Hawaii.  But the op gave me his home call:  WB8YYY.  Curt is a SolderSmoke listener.  In a follow-up e-mail he alerted me to the web site of AA8V.   Great stuff.  Thanks Curt.

Here is the AA8V workshop:

http://faculty.frostburg.edu/phys/latta/ee/workshop/workshop.html#electronics1

AA8V was on the QSO Today podcast not long ago. 

Monday, June 26, 2017

FDIM: Bob Crane Interviews Ashhar Farhan VU2ESE

At Dayton,  Bob Crane interviewed our friend Farhan VU2ESE.  Farhan shared insights on the BITX, the Minima and future rigs. 

Farhan was inducted into the QRP Hall of Fame at this year's FDIM event.

You can listen to the interview here:

http://soldersmoke.com/FDIM17VU2ESE.mp3

Sunday, June 25, 2017

Mod to Correct DESIGN ERROR in Heath HW-8

130k resistor inside heat shrink, across R-24
SPRAT 161 (Winter 2014/15) had a very intriguing article about the Heath HW-8 by Dave M0CEM.  Dave wrote about a possible design error in the active filter of the receiver.  The center frequency and gain shift significantly when you switch from "Wide" to "Narrow."   I was very interested because for many years I have noticed this problem in my own HW-8.  I just left it in "Wide" and never used the more narrow filter.  
 
Dave did some excellent circuit detective work and determined that the problem was R24.  He prescribed a change:  instead of 82k it should be 49.8k.  The placement of a 130k resistor across the 81k R24 would have the same effect.

Yesterday morning I installed Dave's mod.  I did as he suggested and put a 130k resistor across R24.  Brilliant!   What a difference!  In the past, I noticed a significant degradation in signal strength when I put the filter in the "Narrow"  position.  This doesn't happen now -- the response obviously does narrow, but the center freq stays the same.

It is really amazing to me that the Heath engineers made this error, and that it went uncorrected for so many years.  There have been many, many modification articles for the HW-8 over the years, but I haven't seen any that really address this problem. 

If anyone has more info on how this design error happened and why it went uncorrected for so long, please let me know.

Thanks to Dave and SPRAT for getting us back on the straight and narrow. 

Saturday, June 24, 2017

Straight Key QRP Homebrew Adventures -- TRGHS


Last Saturday I put the Tuna Tin Two Top together with my Herring Aid Five 38 (year) Special and the Indian key that Farhan gave me.   I discovered that some of my 40 meter CW FT243 crystals had disappeared into the entropy of the shack.  But I was able to find one for 7050 kHz. That was a bit of good luck because it turns out that 7050 is the frequency of a congenial group of operators known as the Straight Key Century Club.  I felt right at home.  I have been inducted.  My SKCC number is 17272.  Very QRP, don't you think?   It is almost a Vanity SKCC.  Clearly, TRGHS.

I have been having excellent luck with this 7 transistor rig.  I have had one contact each day since I put it on the air, all of them in response to my CQ calls.  I've worked:

K1PUG Hank in Connecticut (twice)
W8HOG  Jerry in Ohio
WA4GQG Kevin in North Carolina
WA2AAW Frank in New York
KM4FO Dwight in Kentucky

This morning I added a little piezo buzzer for sidetone.  I am thinking of adding a VFO to the Tuna Tin.

Friday, June 23, 2017

The Possible Inspirations behind "Juliano Blue"

Close in color don't you think?  Dave Ishmael WA6VVL noted the NC-270 receiver's color was "Cosmic Blue."  Indeed, National noted the unusual color ("outstandingly different") in its advertising.  This now-rare receiver was produced between 1960 and 1964, so it could have influenced Pete.  Of course, the CK-722's color could also have played a role...   


BTW, shouldn't we ask Pete to get out his guitar and give us some "Juliano Blues"?  We need some music to go with the paint.

Thursday, June 22, 2017

More "Canned Seafood" Homebrew CW, from KA4IBG

Bill:

My xYL hates sardines, but they look good together !

In the late 70's the community had a fetish for canned seafood and DC receivers. Do you remember the 80m Sardine Sender ? How about YL Special ? (QST Oct and Jan 1979.) I married them together in a kludged-together box made out of a bent rack-mount panel and defunct aluminum chassis cover.


The bottom board is the rock-bound transmitter. The upper deck is the receiver board. The little mini box contains VFO (so cute.) The 741 audio board is tucked under the scrounged ¼ inch jacks.



Super simple, but lots of fun. It's a handy rig for the week at the beach, although 80m propagation and beach week are 6 months out of phase.

Ed Hlywa
KA4IBG

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