Antennas and National Monuments

We started SolderSmoke 185 with a brief description of my recent ascent to the top of the Washington Monument.  A few days later I was visiting George K9GDT's wonderful web site
http://www.qsl.net/k9gdt/radio/radio.htm  and in the humor section came across the above Gil cartoon from 1959.  That is the general idea. 

Pete then sent me this:

Pete originally had a three element Yagi coming out of Teddy Roosevelt's head, but that just wasn't right.  I asked that it be changed to a 17 meter Moxon.  Thanks Pete.

I would like to note for the record that I have no intention of using the Washington Monument, the Statue of Liberty, Mount Rushmore or any other national monuments as supports for any Yagis, Moxons, Cubical Quads, Ray Guns, Lazy H's, Inverted L's or any other type of electromagnetic wave launcher.

75 and 40 Meter AM on my HQ-100 (Videos) + Digital Display

And here is how I sample the oscillator frequency for the digital counter.  I use an old trick:  I wrap some wire around the oscillator or mixer tube.  I made the coil out of an old coil form. I had to play around with the number of turns to get suitable pickup on both 160 and 40 meters.  The San Jian board allows for IF freq offset.  I use a similar arrangement on the transmit side with the DX-100.  By the way, the box that houses the two displays is the carcass of one of the Heath QF-1 Q multipliers from which I heartlessly pulled the nice reduction drive variable caps for use in my BITX rigs.  

Add caption

Sputnik Replica Transmitter, an "Error" in the Sputnik Schematic, and Why 20.005 MHz?

Mark K6HX pointed me to very interesting Hackaday article on Frank PA3CNO's Sputnik transmitter replica.  As blog readers will recall, we went through a period of Sputnik-mania a few years ago:  http://soldersmoke.blogspot.com/search?q=sputnik  Chief Designer Comrade Mikhail Rainey AA1TJ sent me some of the Russian tubes (like those pictured above). 

The Hackaday article pointed to our post reporting that Oleg RV3GM had found the schematic:

http://soldersmoke.blogspot.com/2013/04/sputnik-schematic-found.html   Stefan reports that PA3CNO found "an error" in the original Soviet schematic:

http://www.radio.cc/post/Franks-power-supply-for-sputnik    A mistake you say?   HAH, I say!  Hah!  This must have been part of a sinister commie plot to prevent the capitalist imperialists from ever being able to reproduce the glorious transmitter of the Soviet people.  They almost succeeded. 

Just kidding.  

In the course of looking through our old Sputnik posts, I came across a question I posted:

I have a question: OK so the crafty Soviets picked 20.005 MHz for some good reasons: Being so close to the WWV freq, it would be easy for hams and SWLs to find it with precision. In the November/December 2007 issue of "Break In" (from NZ -- thanks Jonathan-san!) ZL3DW notes that this frequency selection would allow a receiver set to exactly 20 MHz to "produce an audio tone plus or minus the Doppler shift without ever going through zero beat." But zero beat with what? Most of the receivers out there would not have had BFOs, right? So the Soviets wouldn't have been using ordinary CW, right? Were they using AM, with the beeps produced by an audio oscillator modulating the carrier? 

Was their diabolical plan to use WWV as the BFO for those using ordinary AM SW receivers?   If so, a 5 kHz separation from WWV seems to be too much right?  Especially when the Doppler shift on approach would push the frequency up a bit. Maybe they just chose this freq to make it easy for listeners to find -- just a bit above WWV.  Comrade Rainey surmised that they were keying the PA stage -- the oscillator "backwave" was at times audible on the ground.

What do you think Comrades?

DSW and 73.

The Power and Potential of Small Computers (Quad Copter Videos)

Start by looking at this one: 

https://www.ted.com/talks/raffaello_d_andrea_meet_the_dazzling_flying_machines_of_the_future

Then, for more details, look at these:

"Hot Iron" New Issue, Great Articles

I was very pleased to find Tim Walford's "Hot Iron" journal in my e-mail this morning.  Lots of great articles in this edition, including one by a fellow we know:  Pete Juliano!  Pete writes about our esteemed dual gate MOSFETS.  All hail the 40673!  There is also a nice article about superhet receivers using a 6 MHz IF and a very convenient analog LC (yea!) oscillator arrangement.  Another discusses how to use Huff and Puff stabilizers to take care of VFO drift. N4HAY describes his initial foray into the world of homebrewing and how EMRFD helped him.

Hot Iron is free.  Tim writes:  

"Hot Iron is published by Tim Walford G3PCJ of Walford Electronics Ltd. for members of the Construction Club. It is a quarterly newsletter, distributed by e mail, and is free to those who have asked for it. Just let me know you would like it by e mailing me at electronics@walfords.net"

Thanks Tim!

SolderSmoke Podcast 185 -- SPECIAL FEBRUARY ANTENNA SHOW

SolderSmoke Podcast #185 is available

22 Feb 2016

http://soldersmoke.com/soldersmoke185.mp3

Travelogue:  550 feet above Washington DC

Bench reports
Pete:  Simpleceiver update.  Adventures in Raspberry Pi SDR.
Bill:  A daring but failed attempt at divide by 2 I&Q.
Audio Mods on the Hammarlund HQ-100.
Dual Digital Readout for the AM station.

SPECIAL FEBRUARY ANTENNA DISCUSSION
Why we build antennas in February.
Why hams should concentrate on antennas.
The importance of noodling.
Pete's beam project.
Pete's Lazy H.
The pernicious influence of automatic antenna tuners.
Bill's Ray Gun Antenna.
Bill's Moxon and his 160 inverted L.

MAILBAG
Tom Gallagher NY2RF (new ARRL Exec VP).
Mike Rainey AA1TJ on the air with a unijunction transistor.
Dale W9DKB sends me 160 meter book.
Alan Wolke W2AEW builds a Mighty Mite.
Daniel HK4DEI builds a DSB rig in Medellin.
Chris KD4PBJ modulates an AD9850.
Charlie ZL2CTM Builds a Teensy Superhet.
Jim W8NSA -- a Tek 465 goes toes up.
Thomas KK6AHT has roof, needs antenna!
Grayson TA2ZGE homebrewing crystal filters in Ankara.
Ian G3ROO and I had QRP QSO in 2001!
Steven G7VFy sent me a box of VALVES.
Frank KM4AXA repairs a rig and thus adds SOUL to the machine.

Design Wisdom from Allison, KB1GMX

Allison KB1GMX has helped me out of numerous battles with recalcitrant amplifiers.  She provided an interesting contribution on the r2pro mailing list thread that I referenced yesterday:  

Interesting thread...

 I see Rick as having provided the basis and tools and it up to the collective 'US" to use them to 

create that next generation radio.  All you have to do is decide the performance and 

then go about looking at the means to do so.  All the blocks are there.

Dynamic range, how much is enough?  When I'm portable or mobile raw sensitivity is 

more useful as the antenna is usually a compromise.  Overload is easy to handle with

switchable attenuator.  The exception to this was a radio designed for contesting in a 

hostile environment (a KW user 800ft away) if you burn power you get overload 

performance.  Its not a battery friendly radio (RX power is over 1A for headphone output).

Look at what you need and not what you want.

TX power is just adding stages.  I've worked MOSFETs, LDMOS, GaN FETS and there 

are some pretty cool devices out there and some not designated for RF are cheap.

If all else fails the IRF510 gets both raves and derision.  At 12V its a tepid device

but at over 20V and at 24V it starts to wake up and really perform. I've run The WA2EBY

design for a few years at 45W level using two of those push pull at 28V and its clean and 

solid and the original pair are now over 6 years old!  I also run 8 of them  (4x4push pull) 

at 32V at 6M for a cool 210W  with good IMD.  I'd add all the good (high gain, low IMD) 

power fets perform better at 28  or 50V.   For those into CW consider class E as I've 

worked with this and using GaN fets have generated 15W with 82% efficiency at 

13.56mhz (includes driver and osc) and using the lowly IRF510 at 12V a full 10W 

with 85% efficiency. Class E can be amplitude modulated.

As to the thermionic FETs, a 6AU6 crystal osc driving a 5763 for 10W  gets a lot of raves

on 40M from a buddy that runs CW.  The same deal plate modulated can sound good 

at 5-6W AM on 75M.  For those that want more a 6C4, 6aq5, 6146 will get you over 

50W on CW and 25W AM.  Change the bias a little and inject IQ SSB into the driver grid

and be running 50-80W PEP.  A 12BY7 or 6CL6 driving a pair of 6146 will get you into 

the 180-200W DC input range for about 100W.   Remember the hybrid radios solid state 

low level and rugged tubes for the heavy lifting.  The Pi network (or Pi-L) will load anything 

from about 28 to 100ohms more if you use enough taps and variable caps.  That and DC-DC

converter for the HV are not terrible at 80% or better (even the 1960s transistor designs 

were better than 75%).

In the end it all starts with the receiver.  For that you can always start with a 1T4 RF and 

a 1R4 converter and a 1T4 as regen driving a 3V4 audio.  Power it with 45V (five 9V battery)

and a C cell and go portable.  It should run for a very long while.  Hollow fets run well at low 

drain currents.  :)

Allison