N8NM's SAVED VFO 30 Meter Rig

In early December Steve Murphy N8NM picked up this "mystery box" at a hamfest.   Dr. Juliano identified it as an old CB VFO.  Even though Steve is deeply committed to the dark side of frequency generation (digital synthesis) I was able to convince him to put this VFO to legitimate and proper amateur radio use AS AN ANALOG VFO.  I mean just look at that dial!  It would be a sin to connect that beautiful mechanism to a rotary encoder.   We see the results below.

Bill: 

The 30m rig that I had hoped to have QRV for SKN is finally ready to hit the airwaves!  I still have a few odds and ends to tidy up, but it's essentially done.

Where I ran into problems was my original choice of IF and VFO frequencies: I'd gone with a 13.51 MHz IF because I had the rocks, but that put the 3rd harmonic of the VFO right in the middle of the band.  Oops.

Moving the IF to 13.56 fixed that problem, but I still had a spur from that harmonic that needed to be filtered.  At first, it looked like a trap on the output of the VFO would squish it, but it ended up requiring a few extra poles of bandpass filtering to get it below -40 dB/c.  Now we're legal.

Anyway, here's a few pics. The chassis are bent from 22 ga aluminum on my trusty Harbor Freight brake.  They're almost square, they look cockeyed because I still need to make brackets to hold the top and bottom together.  The heat sink is overkill for 5 watts, but it was cheap :-)

Electronically, almost everything between the audio and power amps is straight-up Bitx.  The power amp uses a RD16HHF1 driven by my spin on Farhan's RF-386, and the audio is an LM380 driven by an LM324, with gating between CW and digital mode input handled by a CD4066.  The CW tone generator is based on WB0RIO's "clickless" sidetone circuit, which, while a little complicated, creates perfectly formed CW elements that really sound nice.

I'm still amazed at the stability of the LC VFO; I was monitoring JT65 signals over the weekend and noticed zero drift after warm-up.  To keep it ready to rock, it's powered from the "hot" side of the on/off switch, as is the CW oscillator. 

I can't think of much else to say about it...  It is what it is :-)

73 - Steve N8NM

Of Waterfalls, SDRs, and Homebrew Analog Rigs: Words of Wisdom from W8JI

W8JI

It happened again today. Conditions were good and I was BOOMING into the NYC area on 40 meters.  40 over.  Everyone liked the signal and said it sounded great.  Except for one anonymous grump who chimed in to say that I was "9 kc wide."  I imagine he was basing this on a quick look at his super-dooper SDR waterfall, without any consideration of signal strength or the characteristics of his own receiver. Sigh.  The Waterfall Police had struck again.  

OM W8JI gives a great description of the pitfalls of this kind of "you're-too-wide-because-my waterfall-says-so" reasoning.  Check it out.  And keep it handy in preparation for your next encounter with the 40 meter Waterfall Police.  

https://www.w8ji.com/checking_bandwidth_with_receiver.htm

Wonderful "QSO Today" Interview with Ian Keyser G3ROO

N2CQR and G3ROO

I knew it was going to be a good Sunday morning in the shack when I saw that Eric 4Z1UG had posted an interview with Ian Keyser G3ROO.   This wonderful interview brought back memories of my visit to G3ROO's amazing facility in Dover.  (Thanks to Tony Fishpool who brought me out there.)

In this interview, you will hear Ian state -- in a very nonchalant English way -- that he built his first receiver at age 8.  And I really loved the story of how Ian got his call sign.  FB Ian.  

Ian is a very prominent member of the G-QRP club.  I was oddly relieved to learn that he is working on a LEGAL LIMIT LINEAR AMPLIFIER.  I hope he has special dispensation from Rev. George Dobbs.  I intend to cite this project if we ever have to defend Pete Juliano from charges of QROism.

Listen to the interview here:

http://www.qsotoday.com/podcasts/g3roo

That is a key designed for use aboard a hydrogen balloon.  This is the kind of thing that Ian has in his shack.

 

This is Ian's variometer -- mentioned in the interview.

That's me using one of  Ian's spy sets. 

Ian's antenna book:

http://www.lulu.com/shop/ian-keyser/practical-and-tested-aerial-systems/paperback/product-10904725.html

Here are the SolderSmoke Daily News posts about Ian and the Dover Construction Club:

http://soldersmoke.blogspot.com/search?q=Dover

BITX40 to BITX40 In Australia -- Both Rigs on the Beach, Video at Both Ends

There is so much great homebrewing going on down-under.   It makes me jealous.  And so much of it is for phone.  FB.

I really like VK3YE's sand graphic proclaiming to the world (or at least to the beach!) that a BITX40 to BITX40 contact had been made. 

Looks like both rigs were using VK3YE's ceramic resonator mod for the VFO.

Be sure to check out the BITX 40 Mods blog:
http://bitxhacks.blogspot.com

N6ORS's Franken-SDR Superhet

Of course, I love it.  MOSFETS!  NE602's!  10.7 Mc IF cans!  Cycles, not hertz! And a Tayloe Quadrature Sampling Detector made from junkbox parts from the Reagan administration. FB Keith.   And the frequency display is icing on the cake.  

Bill:

I thought the group might find my new Franken-SDR interesting.
It is an SDR with a superhet front end. 

I wanted to play with an SDR but I didn't want to get a kit or buy
parts, so I scrounged through he drawers and found a mux chip
cd-4016 circa-1980 some old 7400 logic that is probably per-1980.
This could make a QSD but only very low frequencies. Well I thought
how about at IF frequencies?

The frontend is a MOSFET mixer (1975) , the 10.7 IF is a dual gate MOSFET
(1975), the second mixer is a NE602, the IF cans are all stagger tuned to
give a bandwidth of 50kcs.
The only thing modern is the DDS but I old-time-ifyed it with BCD switches.

Keith N6ORS

VK6FTH did something similar: http://www.vk6fh.com/vk6fh/SDRradio.htm

Understanding the "O" (organic) in OLED

That's the one I'm using.  Less than 1 inch on each side.  No back light.  8 bucks shipped:
https://www.amazon.com/gp/product/B00KRZY7PW/ref=oh_aui_detailpage_o07_s00?ie=UTF8&psc=1

Here is a thorough description of the technology:

https://en.wikipedia.org/wiki/OLED

Boatanchors! HT-37 to HT-37 contact with W1ZB

Jerry W1ZB and I met up on 40 a week or so ago.  He was running a Hallicrafters  HT-37.  This spurred me to clear up the T/R problem that had knocked me out of the competition on Straight Key Night  (I'm sure I would have won!).  One spray of DeOxit D5 on the HT37 relay contacts was all it took.  Jerry and I set up a schedule for this morning on 40 minutes.   Above you can see a short video of the first part of our HT-37 to HT-37 contact.

Jerry has an amazing collection of beautiful old tube radios.  Check out his QRZ.com page:
https://www.qrz.com/lookup/w1zb

BTW:  Speaking of old rigs talking to identical old rigs:   Last night on 40 I worked TI2NF in San Jose, Costa Rica.  He was running a Collins KWM-2 to a Collins 30-L1.  It was real nice to talk to somebody who was using an unusual rig.  Right after we finished, VE3OCZ called  TI2NF.   VE3OCZ was ALSO running a KWM-2 to a 30-L1.   TRGHS.  

Great Interview with Farhan Re BITX 40 and BITX History

W5KUB has a really good interview with Farhan.  There are several spots where the Skype connection gets quite choppy, but hang in there -- it gets better.  Farhan provides a lot of good info on the history of the BITX rigs, his design philosophy, and the importance of the EMRFD book.  He also talks about how the BITX 40 Module is produced.  And he talks a bit about possible future rigs.  Great stuff. 

I was very pleased to hear that Farhan is trying to eliminate the need for his FT-817 (he currently needs it for its general coverage receiver) so that he can have a completely homebrew hamshack.  FB! 

NE602 Si5351 OLED "Whole Foods" Receiver

This is one of those projects that sort of just happened.  First I built an Si5351/Arduino synthesizer with a small OLED I2C display (program by Thomas LA3PNA -- thanks Thomas).  Tom Hall AK2B up in New York helped me get the Si5351 VFO and BFO going -- thanks Tom.  Then, over the holidays I decided to build a rig of some sort around the Si5351.  I started with a superhet receiver using an NE602 as the mixer and another as the product detector.  I power the NE602 with an 8 volt regulator from W8NSA -- thanks Jim.  I made a 4 crystal 11 MHz Cohn filter using crystals left over from a BITX project.  The software from AADE helped me design the matching networks to match the filter to the 1500 ohm impedances of the NE602s.   I built the circuits on a milled board sent to me by Pete Juliano N6QW -- thanks Pete!   I put a dual tuned circuit at the front end, going into a MOSFET RF amplifier.   For audio amp I have an LM386.  The whole thing is screwed down to a barbeque grilling plank from Whole Foods -- thanks Whole Foods!  (This seems appropriate -- the "O" in OLED is for "Organic"!)

It sounds nice.  I may eventually try to put some relays in to switch the NE602s and the filter around to make this a transceiver.

Straight Key Night -- Bandscan from WA6ARA (audio)

WA6ARA SKN Station

Mike Herr WA6ARA was on 40 meters with old gear this Straight Key Night.   Mike was receiving with a venerable Heath HR10B.  One of his favorite QSOs was with Keith W6SIY; Keith was running Conar twins that had the kind of "swing" that stirs up the kind of memories that SKN is all about.  FB.  Mike made a bandscan recording of what 40 sounded like, and he made another of W6SIY's beautiful signal.

You can listen by clicking on these links:  

http://soldersmoke.com/SKNBANSCAN.mp3

http://soldersmoke.com/SKNQSO.mp3

My own SKN effort was cut short this year by technical difficulties.  The HT-37's relays stopped doing their thing.  Probably the relay drive tube going soft.  But I did manage to make two great contacts on 40:

WA6URY is in Los Angeles.  This was a very timely contact -- my wife and I went to see the movie "La La Land" on New Year's eve -- the film features a lot of beautiful LA scenery.  Dan was running a kilowatt to a 2 element Yagi on 40.  He too owns an HT-37 and a Drake 2B.  He was on a straight key "with dirty contacts."  FB Dan, thanks.

And then I worked W1PID!  Wow! Jim is well known for his operations from field locations and for his intrepid participation in many of the radio adventures of Michael Rainey AA1TJ.  Jim was on the Maine sea coast expedition when Michael was attempting to cross the pond with his voice-powered radio.  On SKN Jim was in New Hampshire running 35 watts to a Windom off-center fed dipole.  His Morse key is a Kent.    TRGHS.   Thanks Jim.

Happy New Year!

W1PID Maritime Mobile