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Re: Qrp-labs and a Huff and Puff circuit board

Hans Summers
 

Hi all

Huff & Puff was a passion of mine. I was licensed in 1994, but for various personal reasons did not go on air. I did keep reading RadCom (monthly journal of the RSGB) and was fascinated by the Huff Puff articles which appeared in Pat G3VA (SK)'s monthly "Tech Topics" column. I collected everything I could find about Huff Puff and started making my Huff Puff library, eventually putting it online on my website that I created, initially just for this purpose, in 1999. So... everything grew from these roots!

In late 2001 David WN5Y emailed me and we started discussing Huff & Puff, he was using it in his "Electroluminescent Receiver" which he still to this day sells as a kit see http://www.pan-tex.net/usr/r/receivers/index.htm - and I actually finally purchased one of his kits a year ago but still have not finished building it! Anyway - as a result of that correspondence, I decided to also build my first Huff Puff circuit. It was also the first time I had built ANYTHING at all for 8 years. I wanted to try the magnetic field method of varying inductor core permeability that David used. The result was my stabilizer http://hanssummers.com/huffpuff/fast.html and I built a 14MHz VFO that was stabilized by this circuit. 

That then became, with a mixture of other circuits also from Pat G3VA (RIP)'s column - such as the Tayloe detector (Quadrature Sampling Detector) and Polyphase networks - my first amateur radio receiver which you can read about here: http://hanssummers.com/polyphase
Then I built my 1-valve (tube) CW transmitter http://hanssummers.com/cwtx which was also from G3VA's column. 
My ATU was built around 1984 and was also a RadCom project at some point see http://hanssummers.com/atu 

That was the station, in March 2002, that I used for my first ever QSO see http://www.hanssummers.com/cwtx/cwtxfirstqso.html 

So. This Huff Puff stuff is a very important part of my personal radio history. Later, the hanssummers.com website was expanded to include lots of old projects, and I started adding new ones... so really 2002 was the birth of my amateur radio life. 

Anyway I wanted to say a few things about Huff Puff. 

1. PLL vs FLL is a debate that raged on sometimes (PLL = Phase Locked Loop, FLL = Frequency Locked Loop). A Huff Puff circuit is not exactly like either. You can make a reasonably convincing argument for why it is not a PLL or why it is not a FLL. However if the assumption, from your proof that it is not a PLL, is that therefore it must be a FLL... or vice versa - then you probably start falling into difficulty. I think not everything is as simply classifiable into one of two categories. 

2. A Huff Puff circuit doesn't exactly lock a VFO precisely on any particular frequency. What it does is compare pulse edges and try to line up the pulse edges. One is a divided down timebase, the other is the VFO. Actually which one is divided down can be swapped. It is continually hunting, around a target frequency. There are multiple stable target frequencies, separated by typically 10, 20, 30Hz etc depending on how your circuit is designed. The Huff Puff circuit will try to steer the frequency to the nearest target frequency. 

3. One critical aspect of Huff Puff is that the correction power of the circuit must be sufficient to correct any drift occurring, but not so aggressive that it overcompensates or that it does not allow you to tune the VFO normally. This is quite hard to set up properly. If the correction capability of the Huff Puff is too weak, then the VFO my drift far enough before being corrected, that the Huff Puff circuit "jumps" to trying to move it to the next stable target frequency. If the correction capability is too strong then it would make it hard for you to manually tune the VFO; additionally it makes for large excursions around the target frequency (which if extreme, could also make it "jump" to the next target frequency. 

4. If correctly set up, the Huff Puff circuit does not add much in the way of any objectionable sidebands or phase noise. In the days when PLL synthesizers were often not well designed, leading to quite high levels of phase noise, the way a Huff Puff circuit retains the cleanliness of the underlying VFO was said to be one of the advantages. That and the inherent simplicity (low parts count, at least). 

5. As Allison KB1GMX said, and what Pat G3VA said before, something like: "A Huff Puff circuit does not turn a bad VFO into a good VFO; it turns a good VFO into a better VFO". Every effort should be made, to make the VFO as good as possible before trying to add a Huff Puff circuit to make it really perfect! 

6. The "Fast" style Huff Puff circuit developed initially by Peter G7IXH, is effectively like an array of ordinary stabilizers all acting in parallel on the same VFO. What it allows you to do, is
a) stabilize a worse VFO 
b) stabilize a good VFO better
Using it for a) is not a good idea, according to the make-the-VFO-as-good-as-possible-first principle. Stabilizing a good VFO better, means that you can make the Huff Puff corrections much smaller, it means that the frequency excursions become a lot smaller. The circuit is also a lot more forgiving when setting it up. 

7. Some practical and simple designs I worked on are here: http://www.hanssummers.com/huffpuff/minimalist.html , which are targeted towards minimalist implementations. The 1-chip version http://www.hanssummers.com/huffpuff/minimalist/1chip was an experiment to really see how far a Huff Puff stabilizer can be minimized. It is very inefficient and not easy to set up. I don't recommend it for other than curiosity value. The 2-chip "Fast" type http://www.hanssummers.com/huffpuff/minimalist/2chipfast.html with discrete-component XOR gate (though an ordinary XOR gate could also be used) is a good circuit, it works reliably and efficiently and isn't fussy to set up. 

Overall Huff & Puff circuits are a bit dated now but who cares, they are really fascinating to play with and very educational. 

73 Hans G0UPL

Re: QRP rags to riches #qcx

David Birnbaum
 

Started on IBM 650 with direct machine instructions.  Then FORTRAN (no #), FORTRAN II on IBM 70954, 7044, PDPs 1,5,6,7,8,9,10, CDC6600, C on various microprocessors and Postscript (yes it''s a programming language).  Now content with Linux on IBM PC, plus R-Pi and Arduino.

dave
k2lyv

Re: Listening to WWV & WWVH on 5000 kHz this morning, on the QCX-80

n4qa at_hotmail.com
 

Hello, Robert.
Okaaaaay...it's rudimentary as it now stands...

Currently, in the attached screen shot:

Using the app on the left with the QCX-series rigs.
Using the app on the right, (  ca 2000 ), with the SWL DSW-II-series rigs.
Someday, a modified version of the app on the right may replace the one on the left for use with QCX.

Happy to answer any questions which are compatible with my skill set.

72 / 73,
Bill, N4QA

Re: Qrp-labs and a Huff and Puff circuit board

Ed Kwik
 

If I had the time and a HG-10 to play with I would love to take the HG-10 circuit and put it into a modeling program. Then do an analysis to figure out which componets contribute the most to frequency drift and instability. Then see if there are any modern day components that could be used to improve the overall stability.
Ed
AB8DF

Re: QRP rags to riches/Fortran #qcx

jjpurdum
 

When I first got interested in programming microcomputers, I was teaching at Econ at Butler. There was no CS department there, so a colleague and I taught a one-day seminar for the business community on how small computers would benefit their businesses, using the funds to purchase and build 8 SOL-20 kit computers for a COBA computer lab (mainly stats and Lotus 123). Shortly after that, I applied for an NSF grant to study microcomputers in education and got to attend a week-long class with a small group of other professors. The class was taught by David and Peter (Rony). They taught us assembler on a KIM-1, a computer with 256 bytes of memory! Fun times!

Jack, W8TEE

On Wednesday, April 10, 2019, 8:41:49 AM EDT, n4qa at_hotmail.com <n4qa@...> wrote:


How could I forget David Larsen et al of the Blacksburg Group when mentioning the Bugbook series?!
Sorry Dave.
I remember when you guys would come over for a visit and a chat.
72 / 73,
Bill, N4QA

Re: QRP rags to riches/Fortran #qcx

n4qa at_hotmail.com
 

How could I forget David Larsen et al of the Blacksburg Group when mentioning the Bugbook series?!
Sorry Dave.
I remember when you guys would come over for a visit and a chat.
72 / 73,
Bill, N4QA

Re: Listening to WWV & WWVH on 5000 kHz this morning, on the QCX-80

rentwist@...
 

Hi Bill,

Like Ben perhaps, I am left with more questions than answers/understanding.  I am sure many would love to understand more about what you have been doing if you are so inclined to describe it in more detail.

73,

Robert, WA2T

Re: Well, it appears that the QCX-17 is getting out on 15m too...

n4qa at_hotmail.com
 

Thanks, Mike.
In fact, "Leave the low pass filter in place and just put the bandpass/band stop after the output." is exactly what I've been doing.
It's better than butchering the rig, I suppose, but there is that slight loss of signal...both ways.
72 / 73,
Bill, N4QA

Re: QRP rags to riches/Fortran #qcx

Steve in Okinawa
 

Ah yes, same Fortran IV era. 1971 MBA thesis "Counterculture and the Business World", predicting a softer, gentler capitalism (ha!). Hauled stacks of punchcards with survey data up to the Computer Center at Cal Berkeley, returning in about two days for the printout.

Re: Well, it appears that the QCX-17 is getting out on 15m too...

Mike Donovan
 

Consider either a bandpass or band stop filter.  You can use Elsie LC program (downloadable free) to test out the filter.  My bandpass filters matched the test circuit very well.

Leave the low pass filter in place and just put the bandpass/band stop after the output.

Mike.   VE7EPQ 

Re: Qrp-labs and a Huff and Puff circuit board

Mike Donovan
 

First step will be to get a PTO up and running.  I also am looking at a Vackar.  Very fascinating.  One reason to try the PTO is to see if it is quieter than an ARDUINO VFO.  It also draws significantly less current and doesn’t require programming.  Having said that, my first venture with my VFO for the Heathkit DX-60b is my Qrp-labs ARDUINO shield.

thanks Hans, for the great projects.  I have a qcx to build as well as a 5 band filter board for the ARDUINO shield.  Having a great time lately 

Mike.  VE7EPQ 

Re: QRP rags to riches #qcx

n4qa at_hotmail.com
 

Well, if my dad were still here ( W4MAI - sk 2006 ), he could tell you about how a single 8-bit accumulator would fill an entire equipment closet :0)
Many years ago, he worked for IBM  somewhere in upstate New York.
Eventually, he became a college professor, teaching a bunch of kids all about highs & lows and a whole lot more.
Anyone remember the Titus bros and the Bug Book series?...
72 / 73,
Bill, N4QA

Re: QRP rags to riches #qcx

John Kirby
 

  
Does mastering (= PHD) the 8088 count in the contesr?

: o ))
ham 1957
retired 1997
72 73
John
N3AAZ

Re: Listening to WWV & WWVH on 5000 kHz this morning, on the QCX-80

n4qa at_hotmail.com
 

Yes, "we" are.

Simply put, it was fun discovering the parameters of, and avoiding running afoul of Hans' encoder debouncing state machine as I experimented with the "My_encoder_de_N4QA" PC app.

72 / 73,
Bill, N4QA

Re: QCX Repair

Dave N3AC
 

And remember a few weeks ago a new build went thru this... with fried finals, the rx was deaf until finals were changed... receive signal was rf-grounded thru the damaged finals so "nothing" was left for the receiver to work with... Last report here was that it was alive and working after replacing finals.


On Tue, Apr 9, 2019, 15:20 Peter GM0EUL <gm0eul@...> wrote:
Hi Roger
Where about are you?  If its doing everything except transmitting then you're probably right that the output transistors have failed because of transmitting without a load on it.  I'd be happy to have a look if you can't find anyone closer or better qualified.  It is probably a matter of replacing Q1, Q2 and Q3 and confirming that the other transistors are OK.  I'm in south east Scotland.

All the best
Peter, GM0EUL

Re: Panadapter #qcx

Alan G4ZFQ
 

IC5 pins 1 and 7 and it did seem to be baseband audio at that point. I got at least 0 to 24kHz bandwidth
Simon, Michael,

They will be IQ signals but the QCX is not intended to be wideband.
I'd think C4,7,43-46 would really need reducing.

73 Alan G4ZFQ

Re: Panadapter #qcx

Simon Kennedy
 

Hi Michael,

I've tried it from IC5 pins 1 and 7 and it did seem to be baseband audio at that point. I got at least 0 to 24kHz bandwidth feeding my homebrew panadaptor. It was a little experiment into 'what if' rather than anything else so I didn't pursue it.  However, just looking at the circuit diagram it is meant to be DSB at that point so I wonder if it really is baseband audio there.

Be interested to know.

73 Simon
G0FCU.


On Wed, 10 Apr 2019, 04:54 Michael Bridak, <michael.bridak@...> wrote:
Hello, I was thinking that an add-on pan adapter would be a fun project to try.
And knowing just enough to know that I know nothing about this, I thought I'd ask what may be a "simple" question.
Can I get I&Q from pins 1 and 7 from IC5 of the QCX to feed an external pan adapter?
And is it Analog baseband at these pins?
And what's the bandwidth?
and is QSX coming out during hamvention or FDIM, Wink Wink Nudge Nudge say no more.
 

Re: QSX display #qsx

Michael N6MST
 

And with VNC (built into Raspbian) you can operate remote from anywhere! I'm honestly surprised I'm not playing radio from work every day 😅

Re: Panadapter #qcx

Michael Bridak
 

Hello, I was thinking that an add-on pan adapter would be a fun project to try.
And knowing just enough to know that I know nothing about this, I thought I'd ask what may be a "simple" question.
Can I get I&Q from pins 1 and 7 from IC5 of the QCX to feed an external pan adapter?
And is it Analog baseband at these pins?
And what's the bandwidth?
and is QSX coming out during hamvention or FDIM, Wink Wink Nudge Nudge say no more.
 

Re: QSX display #qsx

Michael Sharp
 

One thing I was looking at was using FLDIGI running on a RPi3 as a “front end” for the QSX. Hans says the QSX should interface nicely with JACK (Jack Audio Connection Kit). Coupled with a touch screen, such as the RPi Official Touchscreen, and this will be an awesome rig =)

73,
-Michael
KD9MED