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Showing posts with label 17 meters. Show all posts
Showing posts with label 17 meters. Show all posts

Wednesday, September 21, 2022

Nick's "Shelf-17" Al Fresco Homebrew Transceiver -- Frank Jones Would Approve!


This is a really wonderful video from Nick M0NTV.  

Some reactions:
 
-- Wow, a real celebration of Al Fresco!  And of the wooden chassis -- Frank Jones would be so pleased. 

-- Nick's description of the tales of woe caused by metal boxes is right on the mark, as is his description of the benefits of leaving the circuitry visible.  He's right -- this is an art and science kind of thing. 

-- That's a shelf, but it is FAR from being a shelf of shame! 

-- I am jealous of the S-meter.  I may need to include one of those in future rigs. 

-- Great to hear the shout outs to VK3HN, ZL2CTM, and N6QW -- we are are indeed the IBEW! 

-- I think we can see the N6QW influence in Nick's decision to use a steerable filter/IF amp board.  FB. 

-- I liked hearing Helio PV8AL in Boa Vista.   When I was building simple Direct Conversion receivers for 40 meters, I knew that I had it right when I could hear Helio's roosters in the morning! 

Be sure to watch this video, and to subscribe to Nicks Channel: https://www.youtube.com/c/M0NTVHomebrewing
He has done many other videos providing more details on the various stages that make up this rig. 

I hope to work Nick on 17 HB2HB soon. 

Thanks Nick! 

Wednesday, May 25, 2022

HF Bandsweep with the Hammarlund HQ-100 (video)


It has been a while since we last did a bandsweep.  Too long.  Here is one using my recently fixed up Hammarlund HQ-100.  Repair details are in recent videos. 

For this bandsweep we cover most of the HF band and even briefly dip down into the AM broadcast band: 

Demonstration of the Hammarlund HQ-100: Radio Marti, 40 meter AM, 40 Meter SSB, 40 meter FT-8, 40 meter CW with and without the Q multiplier, classical music on WRMI, WFAX 1220 kHz AM, WWV 20 MHz, CB!, 17 meter SSB, the 20 meter BS position, the effect of AVC and the Noise Limiter, SSB with the internal BFO and with the Q multiplier as BFO. CW with the internal BFO AND the Q multiplier. 

Be sure to subscribe to the YouTube channel.  

Monday, April 25, 2022

75/20 - 17/12 Two Homebrew Rigs in Scrap-Wood Boxes

 



I moved the 17/12 Rig off the workbench and placed it (as planned) atop the Mythbuster rig.  Now I have four bands easily accessible.  In these pictures you can see all four bands being displayed on the San Jian Frequency Counters. 

I found a kitchen drain screen that is an ideal cover for the 3 inch speaker in the 17/12 rig. 


I reconfigured the Low Pass filters in the CCI .1 kilowatt amplifier.  I put a 12 meter LP filter in there in place of the 40 meter LP filter (that I haven't been using much). 

I have been working a lot of DX on both 17 and 12.   

Wednesday, April 13, 2022

The 17 & 12 SSB Transceiver -- Circuit and Build Info -- Video #4


I REALLY LIKE THIS RIG. IT IS LIKE A MAGIC CARPET THAT CARRIES MY VOICE ACROSS THE SEAS.

Cutting Display Hole sets off smoke alarm. Reverse Polarity Protection. IF and Crystal Filter at 21.470 MHz 50 ohms! TRGHS! Amp for VXO Carrier Oscillator/BFO. Mic Amp from uBITX. Transmit/Receive switching from mic connector. VFO: NO DIE CAST BOXES! HT-37 Variable Cap, Frequency Shift. BP filters from QRP LABS designs (G0UPL). TIA amp boards from K7TFC. Needed RF amp to hear band noise. BITX40 PA design, but RD006HHF1 instead of IRF510. Should I run receiver input through LP filter? Frequency Readout Story: How to use one San Jian counter on two bands.

Sunday, March 20, 2022

17 - 12 Dual Band SSB Transceiver On-The-Air

 

It is still completely al-fresco, with all the guts exposed, but I got it on the air this morning.  I was 17, running it through my CCI  .1kW  100 watt amp to a tuned doublet.   Four QSOs so far: HP3SAM, K5BM, N4ZUL, and II3WRTC.   

The structure of the rig is basically BITX. 

The blue boards you see are TIA boards developed by Todd K7TFC. 

No major problems to report.   I will try it out on 12 meters  soon.  The receiver was working well on that band. 

Sunday, March 13, 2022

Video #3 17/12 Transceiver -- Receiver is Working on 12 and 17 meters (Listen! Video!)


Here is an update on the 1712 transceiver project. The receiver circuitry is done and I can listen on 17 and 12 meters. In this video I was using my 75 meter doublet tuned to 17 meters (reception on 12 was pretty good using this antenna). As you can see, I found a temporary solution to the VFO dial problem -- I am using the cardboard tube from a coat hanger super glued to a knob. The tube fits snuggly over the shaft from the VFO assembly.

Hans Summers' QRP Labs Bandpass Filters:



Thanks Hans!


Wednesday, March 9, 2022

Video #2 17/12 SSB Transceiver -- Receive RF Amplifier Needed?


Lots of progress to report on the 1712 rig. 

With just two TIA amps (one on either side of the 10 pole filter) and the AF amplifiers, I now have it inhaling on 17 meters.  But nothing heard so-far on 12. On both bands I can hear the band noise, but just barely.  So I may try some RF amplification ahead of the mixer. What do you guys think about this? I think the two TIAs and the crystal filter are providing 30 db of gain.  

I want to get the receiver circuitry working well on both bands before I build the T/R and transmit amplifier circuitry.
  
It is nice to have a project on the bench!  

I am trying to find a shaft extender or adapter for that big beautiful HT-37 main tuning cap.  The shaft on the capacitor has a width of 1 cm or 0.393701 inches.  I need something that will grab onto that and allow for the connection of a tuning knob.  Please search your junk boxes!  

Wednesday, February 23, 2022

An Analog LC VFO for my 17/12 Meter SSB Transceiver (VIDEO #1)


Here's my initial work on a VFO for my 17 meter -- 12 Meter Single Conversion Dual Band SSB Transceiver. The IF (crystal filter) will be at 21.4772 MHz. On 12 meters the VFO will run from 3.5128 to 3.4528 MHz. On 17 the VFO will run from 3.3092 to 3.3672 MHz.

The transistor I am using is an SK3050 Dual Gate MOSFET. I bought a bunch of these years ago in a panic when I heard that 40673's were getting scarce.

I forgot to mention another important reference: Joe Carr's Popular Electronics VFO articles:

Thanks again to Dale K9NN for the bags of NP0 capacitors. And to Pete N6QW for the suggestion on the HT-37 main tuning cap.   Thanks to Mike WU2D for the great VFO videos, and to Frank Harris for his wonderful book on homebrewing.  And we can't forget the great reference books that guide so many of our projects: Solid State Design for the Radio Amateur and Experimental Methods in RF Design -- thanks to Wes Hayward W7ZOI and all of his co-authors.  

Thursday, February 3, 2022

Exorcism Lite -- Spur Suppressed on 17 meter Transmitter -- Split TX/RX Station On The Air


I spent most of January in the tropics, away from my workbench.  This seems to have had a good effect on my 17 meter split TX/RX project.  As I was leaving, heading south,  I was thinking about several difficult options to deal with my spur problem (see previous blog posts). I thought about turning the transmitter into a transceiver by building a receiver board.   I thought about putting San Jian frequency counters on both the transmitter and the receiver, then doing a visual numerical "netting" by just putting the two devices on the same frequency (I actually ordered 3 San Jian counters).   The counter option was even more complicated than it at first seemed -- I would have to build a converter to shift the RX VFO frequency up.  VK2EMU suggested a tube type "Magic Eye" (interesting idea, but also complicated).   This was getting out of hand. 

When I got back home, I took a new look at the problem.   I decided to take one more shot at suppressing the 8th harmonic of the carrier oscillator.  I had already built a new oscillator and buffer using the circuit from Farhan's BITX20.  And I had put it in a metal box.  Now I decided to do three things: 

1) Tighten up the low pass filter at the output of the buffer by moving the cutoff frequency lower (to around 7 MHz) thereby getting a bit more suppression at 41 MHz

2) Try putting a series LC shunt circuit tuned to 41 MHz  at the output of the carrier oscillator (between the oscillator and the buffer). 

3)  Reduce the voltage to the oscillator/buffer.  I have this on a pot, so I can adjust it down to the point where the remnant of the harmonic is no longer audible, while keeping the main carrier osc signal sufficiently strong. 

It seemed to work.  I could now hear the desired frequency for spotting, without the confusing tone from the spur.  

Why had I been able to do this back in 2002 in the Azores using a simple trimmer cap to ground?  My guess is that I was using my Drake 2-B as the receiver.  The trimmer cap to ground may have reduced harmonic output.  And I was probably cranking back the RF gain on the 2-B to the point where I could hear the desired signal but not the remnants of the spur.  I have no RF gain control on the Barebones Barbados receiver that I am using in this project. 

So, what's the lesson from all this?  Well, if you are faced with a serious technical problem, and you find yourself considering complicated and difficult solutions,  go to the Dominican Republic for about a month (especially if it is January or February), and then take another look at the problem when you return.  If you are unable to travel this far or for this long,  taking a walk or taking a weekend break from a troublesome problem will likely have a similar mind-clearing effect. 

The video above shows part of a February 1, 2022 QSO with Gar WA5FWC using the split TX/RX 17 meter rig.  Gar is an amazing long-time SSB homebrewer who got his start with phasing rigs back in the day. 

Wednesday, February 2, 2022

The NCDXF/IARU Beacons (very useful website)

 

So there I was, innocently checking the lower end of the tuning range on my now 17 meter SSB Barebones Barbados W4OP receiver.  I had it tuned to the bottom of the 17 meter phone band.  All of a sudden I hear YV5B in CW.  It was obviously a beacon transmission. 

I had forgotten about these beacons.  Some quick Googling brought me to a very up-dated web site: 


The site shows exactly which station is transmitting at any given moment.  There is also a very handy map display giving beam headings and distance from your location.  

So far, I'm only hearing YV5B and VE8AT.  I hope to hear more once the Coronal Mass Ejection is behind us. 

Check it out.  Leave your receiver on 18.110 MHz.  Let us know what you are hearing.  

Three cheers for the NCDXF and the IARU! 

Monday, January 10, 2022

Exorcism Not Quite Complete -- Thinking of Other Options

As often happens, I may have jumped the gun in declaring the exorcism of my 17 meter transmitter to be a success. As readers of this blog will recall, my problem was that when trying to "net" my separate 17 MHz receiver and transmitter, at around 18.116 MHz I could hear more than one tone as I tried to get to zero beat.  The 8th harmonic of my 5.176 MHz carrier oscillator was mixing with the 23 MHz VXO signal and producing a spur.  I could probably knock the level of this spur down below FCC limits, but -- and here is the problem -- I probably could never knock it down to the point that it would not be audible in the sensitive receiver that sits right next to the transmitter.  So this is really a netting problem, not really a spur problem. 

I don't want to try another filter frequency -- I have VXO crystals that really work only with a filter at 5.176 MHz.

So here is my current idea:  Build a receiver board and turn this thing into a transceiver.  Switch with relays the input and output of the 5.176 MHz filter, and use relays to switch to the receiver board the VXO and carrier oscillator signals. 

Making this thing a transceiver would eliminate the need for netting.  This should solve my problem. 

What do you folks think? 

73  Bill 

Tuesday, December 28, 2021

How to Fix the Spur Problem in my 17 Meter SSB Transmitter?

 

I built the transmitter almost 20 years ago.  It is in the larger box, which originally housed a Heathkit DX-40.  There is a lot of soul in that old machine.  Details on this construction project are here: https://soldersmoke.blogspot.com/2021/12/junk-box-sideband-from-azores-2004-qst.html  (The smaller box is a Barebones Superhet receiver set up for 17 meters.) 

In the 2004 QST article I discuss a problem I had with "spotting" or "netting."  This is something of a lost art, something that you had to do back in the pre-transceiver days, when running a separate transmitter and receiver.  This was how you got the transmitter on the receiver's frequency.  Essentially you would turn on the carrier oscillator and the VFO and let a little signal get out, enough to allow you to tune the VFO until you heard zero beat on the receiver.  My problem was that around one particular frequency, I would hear several zero-beats.  This made netting the receiver and the transmitter hard to do.  

Important note:  This is really just a problem with the "netting" or "spotting" procedure -- the problematic spur does not show up in any significant way in the output of the transmitter.  I can't see it on my TinySA.  But it is strong enough to be heard in the unmuted receiver sitting right next to the transmitter. And that creates the netting problem. 

In the QST article, I said that I noticed that the problem seemed to be centered around 18.116 MHz.  As I approached this frequency, the tones -- desired and unwanted -- seemed to converge. That was an important clue.  In the article I said I thought that I could eliminate the problem with just one trimmer cap to ground in the carrier oscillator, but looking back I don't think that this really fixed the problem. 

I recently took a fresh look at it.  Exactly which frequencies were causing the unwanted signals that appeared in my receiver? 

I used an Excel Spread sheet to find the culprits. 


The first column shows the carrier oscillator and its harmonics.  The second column shows the VFO when tuned for a signal at 18.11668 MHz (23.2927-5.17602), along with its harmonics.  Check out the 10th harmonic of the carrier oscillator and the third harmonic of the VFO: 69.8781-51.7602 = 18.1179.   Those two harmonics would produce the problem I had been experiencing. 

I turned to one of Wes Hayward's programs for confirmation.  Spurtune08 came in the EMRFD software package. Here is what I saw when I plugged in the above frequencies:    


You can see the little spur off to the left of the main signal.  In the program, as I tune the 23 MHz VFO frequency, the spur moves closer to the main frequency as I approach 18.116 MHz, just as it does in the real rig.   Note that I have only turned on the 10th harmonic of the carrier oscillator and the 3rd harmonic of the VFO.  Spurtune08 is very useful.  Thanks Wes! 

So, what is to be done?   For now, I am just restricting my operations on 17 meters to above 18.120 MHz.  (I worked several DX stations with it on December 27.)  But obviously I need to fix this. This rig needs an exorcism.  I think I only need to get rid of one of the harmonics, and the 10th harmonic of  the carrier oscillator seems easier to kill.  I'm thinking of putting the carrier oscillator in an Altoids box, and then adding some filters to knock down the 10th harmonic. 

Here is the G3YCC schematic that inspired this rig.  I used G3YCC's carrier oscillator and balanced modulator circuits, just using a 5.176 MHz crystal and changing the tank circuit in the collector: 


How would you folks knock down that 10th harmonic? 

Saturday, December 18, 2021

On 17 meter CW from Santo Domingo with a uBITX



We are up on the 12th floor of a building in Santo Domingo. I brought my uBITX and managed to check in as baggage a 16-foot crappie fishing pole. I figured I needed to get the 1/2 wave antenna away from the building -- last time I was here I was unable to make any contacts from this location with the antenna stretched along the balcony. Last time I was QRP with an SST transceiver. 

The fishing pole worked well, but I operated with fear that it would fall or that the neighbors would complain). Today I got on 17 CW with the uBITX (more power than the SST), put it on 17 CW and promptly worked W4A, a special events station commemorating E. Howard Armstrong.  Turns out that today is Armstrong's birthday.  TRGHS.  

On the Reverse Beacon Network my CQs were heard by KO7SS in Arizona (very cool skimmer station at 8100 feet!) and by W2NAF (interesting operations in Antarctica, Svalbard and Virginia Tech). 



Tuesday, November 30, 2021

Putting a Barebones Superhet on 17 Meters with an NE602 Converter (Video)


Armed now with a NanoVNA, I took a look at the passband of the 5 MHz filter in my Barebones Superhet (BBRX)  W4OP built it on a Circuit Board Specialist Board.  He put a 5 MHz CW filter in there;  I broadened the passband for phone by changing the values of the capacitors. Here is what the passband now looks like in the NanoVNA: 


This is what DeMaw would call an "LSB filter."  You would get much better opposite sideband rejection by using it with an LSB signal, placing the BFO/Carrier Oscillator slightly above the passband, in this case near 5.002 MHz. 

When I first built the down converter to get the 18.150 MHz signal down to the 7 MHz range (where I had the receiver running) I used an 11 MHz crystal for the NE602's local oscillator.  But this created a big problem:  18.150 - 11 =   7.150 MHz.  That is in the 40 meter band, but note:  NO SIDEBAND INVERSION.   Then in the BBRX  7.150 MHz - 2.150 MHz = 5 MHz  (the filter frequency) but again:  NO SIDEBAND INVERSION.   The signal started as a USB signal and remained a USB signal. 

I briefly tried shifting the BFO frequency to the other side of the filter passband.  If I could get it to around 4.985 MHz, it might work, but because the filter passband was so large, and because the crystal frequency was so low, I was unable to shift the crystal frequency that far.  In any case the results would have been less than ideal because of the "LSB" shape of the filter.  Back to the drawing board. 

I decided to cause one sideband inversion. 

At first I put a 25.175 MHz crystal module in my down converter.  This shifted the 17 meter phone band down to the 40 meter CW band.  It worked, but I cold hear strong 40 meter CW  signals being picked up by the wiring of the receiver (the box is plastic!).  I went back to the module jar in search of frequency that would move 17 meter phone to the 40 meter area (so I would not have to re-build the BBRX front end) but outside the actual 40 meter band.  

I ended up using a 25 MHz crystal in the down converter. 25 MHz - 18.150 MHz = 6.85 MHz WITH SIDEBAND INVERSION.  After checking on the NA5B Web SDR to see that there are no strong signals in the 6.835 to 6.89 MHz range, I retuned the output circuit on the converter and tweaked the input capacitor on the Barebones.  I shifted the VFO frequency down to 1.835 to 1.89 MHz and put the BFO at 5.002 MHz.   The receiver was inhaling on 17 meter SSB.  

One more change to the BBRX:  in his June 1982 QST article, DeMaw warned that trying to get speaker level audio out of the 741 op amp that he used would result in audio distortion.  And it did.  So I put one of those little LM386 boards I have been using into the BBRX box.  I just ran audio in from the wiper of the AF gain pot.  It sounds good.  

In effect this is my first double-conversion receiver.  I usually prefer single conversion, but this project has highlighted for me one of the advantages of double conversion for someone like me who eschews digital VFOs:   Starting with a crystal filter at 5 MHz,  with double conversion I could keep the frequency of the LC VFO low enough to ensure frequency stability.  That would have been impossible with a 5 MHz IF in a single conversion 17 meter rig.  But if I were starting from scratch for a 17 meter rig, I could stick with single conversion by building the filter at 20 MHz,  keeping the VFO in the manageable 2 MHz range. 

Now, on to the SSB transmitter.   The Swan 240 dual crystal lattice filter from the early 1960s needs some impedance matching. 

Thursday, September 16, 2021

The HBR-13C Receiver and the Poetic License of Homebrewers

I've been hanging out on 17 meters with my homebrew VXO-controlled BITX transceiver.  The antenna is my 75 meter doublet fed with window line through a homebrew tuner made from dead ( I swear) DX-40s and DX-60s. I can tune it up just fine on 17 meters, but I realize I probably have lots of nulls and lobes in the radiation pattern.  Apparently one of the lobes is over my old stomping grounds in Panama.  Almost everyday I talk to either HP9SAM or HP3SS. 

Robby, HP3SS, is using SDR gear now, but he was a real homebrewer back in the day.  Years ago he built an HBR-13C receiver. That's quite an achievement. 

Robby -- formerly VY2SS -- told me that he sold his HBR-13C to none other than Joe Walsh, the rockstar from The Eagles.  FB. 

As I was talking to Robby yesterday, I came across this wonderful web page about the receiver: 

https://sparcradio.ca/wp-content/uploads/2015/12/Restoring-a-HBR-13-Amateur-Receiver.pdf

Robby told me that his receiver looked almost exactly like the one on the SPARC site, but he didn't recognize the small box with what looked like a speaker on the chassis.  I told him that my guess was that this was a crystal calibrator in an oven. 

I also told Robby that I feel an affinity with the HBR project, not just because I like homebrew superhets, but also because my call in the UK was M0HBR.  

There are some great quotes in the SPARC pdf: 


The SPARC page led me to the amazing website of Kees K5BCQ: 

https://www.qsl.net/k5bcq/HBR/hbr.html

Here is Kees's QRZ page: 

https://www.qsl.net/k5bcq/

Friday, August 27, 2021

SolderSmoke Podcast #232 -- Mythbuster, Pete's Tube CW Rig, Pete's DC RX and Simple SSB Rig, NanoVNA and TinySA, Very FB Mailbag


SolderSmoke Podcast #232 is available -- Crank it in Robert!


Featuring a guitar intro by Pete "Bluesman" Juliano,  playing his own composition: "Juliano Blues." 

Upcoming GQRP convention and the N6QW rig
Frank Jones and the FMLA -- Possible Victory?
IBEW Stickers:  NASA, Johns Hopkins APL....
Cycle 25 Lookin Better Today:  SFI 93   SN 47
 
Pete's Bench:
Toobular!  A Tube Transmitter
SR-160
Simple SSB rigs around the world! 
KI7NSS's Pacific 40
 
Bill's Bench
The Mythbuster and the Struggle Against the Urban Legend
W2EWL's Cheap and Easy SSB
W4IMP's IMP. Articles in ER by Jim Musgrove K5BZH and Jim Hanlon W8KGI
The Spirit of Homebrew SSB. From Electric Radio K5BZH December 1991
Reduced Front End Gain on the DIGITIA
Back on 17!  HP3SS sells HBR receiver to Joe Walsh
Maybe another Moxon?
 
SHAMELESS COMMERCE DIVISION
 
Test Gear
NanoVNA -- Alan W2AEW helped solve mystery of why NanoVNA not providing accurate readout of circuit impedance.  Over driving.  Need attenuator. 
TinySA -- Limited Resolution Bandwidth.  But you can listen with it!  See video on blog.
 
MAILBAG
-- Google Feedburner to end e-mails from the blog :-(
-- Paul VK3HN -- TIA AGC? Farhan and Paul looking into options 
-- Ciprian's Romanian Mighty Mite
-- Dino KL0S SolderSmoke GIF and graphical presentation on sideband inversion
-- Allison KB1GMX helped me on 24 volts to IRF 510 issue.
-- Dave K8WPE Wabi Sabi and Martha Stewart. And thanks for parts!  40673s!
-- Steve N8NM building a 17 meter rig with 22.1184 crystals in a SuperVXO and a 4 MHz filter.  
-- Dean KK4DAS restoring an old Zenith.  One hand behind your back OM. 
-- Pete Eaton debating SSB or DSB for 17.  Go DSB Pete!
-- Richard KN7FSZ a FB HBer.  Asked about my solid-stating of Galaxy V VFO.  
-- Walter KA4KXX on benefits of no-tune BP filters like Farhan's   FB. 
-- Jack 5B4APL on Time Crystals and Homebrewing in the 4th dimension.  FB OM!  
-- Moses K8TIY listens to the podcast with his young son Robert.  Crank it in Robert! 
-- Farhan and the SBitx on Hack-A-Day
-- Also Tom's receiver from junked satellite rig on Hack-A-Day
-- Todd K7TFC sent in beautiful message about the spirit of homebrewing. On the blog.
-- Grayson KJ7UM was on Ham Radio Workbench with George Zaf
-- AAron K5ATG running a uBitx with a  homebrew tuner and antenna.  Hope I can work him 
-- Heard Mike WA3O last night on 40 DIGITIA.  Water cooled amplifier

Saturday, December 19, 2020

A Very Clever Way to Build a Moxon for 17 and 20 meters



Jim AB9CN sent us Dan Zimmerman N3OX's page in response to my plea for help in SolderSmoke #227.   I think this is a very clever and attractive way to cover both bands with a single Moxon.  

http://www.n3ox.net/projects/2017moxon/

Of course there are other ways to do this -- other listeners wrote in with confirmation that it is indeed possible to nest a 17 meter element inside a 20 meter Moxon (as is done routinely with Hex beams), but this requires a lot of cut-and-try tuning of both antennas.  More in this in future posts.  Thanks Jim, and thanks to all who wrote in. 

I kind of like the N3OX approach.  I think his design makes it more of a workbench electronic project, as opposed to a mere wire and coax antenna project. But hey, that's just me. 

Tuesday, December 15, 2020

SolderSmoke Podcast #227: Solar System, SDR, Simple SSB, HA-600A, BITX17, Nesting Moxons? Mailbag

SolderSmoke Podcast #227 is available: 




Travelogue

Mars is moving away.  Jupiter and Saturn close in the sky.  And the Sun is back in action – Cycle 25 is underway.  Also, the earliest sunset is behind us.  Brighter days are ahead.


Book Review:  “Conquering the Electron”   With a quote from Nikola Tesla. 


No real travel for us:   Hunkered down.  Lots of COVID cases around us.  Friends, relatives, neighbors.  Be careful.  You don’t want to be make it through 10 months of pandemic only to get sick at the very end.  SITS: Stay In The Shack. 


Pete's Bench and Tech Adventures:  

 Backpack SDR  keithsdr@groups.io

 Hermes Lite 2

 Coaching SSB builders

 G-QRP talk  

 A new source for 9 MHz crystal filters


 Bill's Bench: 

Fixing the HA-600A Product Detector.  Sherwood article advice. Diode Ring wins the day.  Fixing a scratchy variable capacitor.  Studying simple two diode singly balanced detectors.  Polyakov.  Getting San Jian frequency counter for it.

 

Fixing up the 17 meter BITX.  Expanding the VXO coverage.  Using it with NA5B's KiwiSDR. 


Resurrecting the 17 meter Moxon.  But WHY can't I nest the 17 meter Moxon inside a 20 meter Moxon?  They do it with Hex beams.  Why so hard with Moxons? DK7ZB has a design, but I've often heard that this combo is problematic.  Any thoughts?   I could just buy a 20/17 Hex-beam but this seems kind of heretical for a HB station.


Suddenly getting RFI on 40 meters.  Every 50-60 Hz. Please tell me what you think this is (I played a recording).  


MAILBAG:  

Dean KK4DAS’s Furlough 40/20

Adam N0ZIB HB DC TCVR

Tony G4WIF  G-QRP Vids.  Video of George Dobbs. 

Grayson KJ7UM Collecting Radioactive OA2s. Why?

Pete found W6BLZ Articles

Rogier KJ6ETL PA1ZZ lost his dog.  And we lost ours. 

Steve Silverman KB3SII -- a nice old variable capacitor from Chelsea Radio Company. 

Dave K8WPE thinks we already have a cult following.

Dan W4ERF paralleling amps to improve SNR. 

Jim W8NSA -- An old friend. 

Pete Eaton   WB9FLW    The Arecibo collapse 

John WB4GTW old friend... friend of: 

Taylor N4TD HB2HB  


And finally, we got lots of mail about our editorial.   No surprise: Half supportive, half opposed.  Obviously everyone is entitled to their opinion.  And we are free to express ours.  It’s a free country, and we want it to stay that way. That is why we spoke out.


Yesterday the Electoral College voted, finalizing the results.  All Americans should be proud that the U.S. was able to carry out a free and fair national election with record turn out under difficult circumstances. And all loyal Americans should accept the results. That’s just the way it works in a democracy.


We are glad we said what we said. It would have been easier and more pleasant to just bury our heads in the sand and say nothing.  But this was a critically important election and we felt obligated as Americans to speak out.  We'd do it again. And in fact we reserve the right to speak out again if a similarly important issue arises.  

Saturday, December 5, 2020

Adding 10 kHz of Coverage to My BITX 17

 
Solar Cycle 25 is underway.  The Solar Flux Index and Sunspot numbers are up considerably.  I have dusted off my old BITX17 transceiver.  This time around I am using it in conjunction with a waterfall display provided online by NA5B's KiwiSDR receiver, which is located about 9 miles east of me. This SDR receiver allows me to see the entire 17 meter band.   It was this panoramic display that made me pay more attention to the fact that the Variable Crystal Oscillator (VXO) that I am using in this rig prevented me from tuning the lower 10 kHz of the 17 meter phone band (18.110 -- 18.120 MHz). 

I use two crystals switched by a relay to cover the band. One is at 23.149 MHz, the other at 23.166 MHz.  The crystal filter is at 5MHz.  With a coil and some caps I could move the frequencies of the oscillator enough to cover 18.120 to 18.168 MHz (top of the band). 

When I first built this thing, I kind of wrote off the lower 10 kHz of the phone band.  I couldn't get the oscillator to work that low, and I was already satisfied with the top 48 kHz.  But the NA5B waterfall often showed SSB stations in that lower part of the band.  I wanted to talk to them.  So I started thinking about how to do this.       

Looking at my schematic (above) I remembered that most of the frequency lowering was done by L1, a 3.2uH toroid.  I figured that to go a bit lower, I would just have to add inductance.  But I didn't want to lower the frequency provided by BOTH crystals -- I just wanted to bring the frequency with the lower crystal down a bit.  

In my junkbox I found a 1 uH coil.  I disconnected the lower lead of the 23.149 MHz crystal from its connection to the relay.  I soldered the 1 uH coil between the crystal and the relay (see picture above).  This moved the lower limit down to 18.087 MHz. 

Now crystal one provides 18.087 - 18.144 MHz 
         crystal two provides 18.137 - 18.167 MHz

So now I have the whole phone band.  Bob is my uncle. TRGHS. 

This was a very quick and satisfying little fix. As Pete says WYKSYCDS: when you know stuff you can do stuff.  Indeed.  And as I re-build and repair gear that I built years ago, I am often reminded that as time goes by, we learn more. We end up knowing more and being able to do more.   

I am also planning on rebuilding my 17 meter Moxon;  this time I will make it better and stronger.         

Saturday, October 31, 2020

SolderSmoke Podcast #226 The U.S. Election, Solar Cycle, uSDX, Hermes, HP8640B, SGC 600 Sig Gen, HA-600A, Mailbag

SolderSmoke Podcast # 226  

http://soldersmoke.com/soldersmoke226.mp3

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About the U.S. election

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Mars:  Setting early, will have to shift to evening observation.  Weather has been poor. 

Sunspot Cycle 25 is underway -- SFI 78, SN 32  

The Gliessberg cycle


Pete's Bench:  #49,  #50,  uSDX,  Hermes Lite


Bill's Bench: HP8640B,  Global Specialties Corp 6000 counter, Lafayette HA600A.


MAILBAG:

Peter VK2EMU Sent me copy of 1947 Handbook.  Thanks Peter

Brad W1BCC Spotted 10 S-38s for 80 bucks on Craig’s list.  What’s going on here? 

Dale K9NN sent both Pete and I care packages with very cool part, including DG Mosfets

Stuart ZL2TW sent me Les Moxon’s Antenna Book.  TRGHS. Moxon will be back! 

Alvin N5VZH got his receive converter with a little Tribal Knowledge from SS. 

GM4OOU The Bitsy DSB rig from Scotland

Peter VK3YE DSBto DC incompatibility SOLVED

Paul VK3HN's Digital SWR and Power Meter and Low band AM TX VFO/Controller FB Videos. 

VK2BLQ alerts us to article about Jac Holzman of Elektra Records. 

AA0ZZ great message on assembler language and writing software the hard way. 


Designer: Douglas Bowman | Dimodifikasi oleh Abdul Munir Original Posting Rounders 3 Column