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Re: QCX 40 Woes

 

¿ªÔÆÌåÓý

Mike,

The first question is what revision of the board do you have? ?If it is 1-3 you need to replace the electrolytics C21 & C22 with 0.1 uF ceramic caps. ?That has worked on 5 radios I have built

72,

Chas - NK8O

On Apr 7, 2019, at 12:42 PM, Mike Corner via Groups.Io <mikescorner@...> wrote:

Just finished my QCX 40 kit and it went together well. Came right up with good alignment and output at 12-16v. Problem is cw sounds terrible through the headphones/speaker. I get a loud click at the beginning and end with about a one second delay on semi-qsk. There is no sideband on anything above 20wpm on full qsk.Rechecked output and alignment which is good. Kinda stumped at this point.

Re: Strange audio issue #qcx

 

¿ªÔÆÌåÓý

Try some freezer spray or a wooden cocktail stick to carefully prod connections.

On 07/04/2019 20:09, KT4RK wrote:

I agree, but I¡¯ve checked it and checked it. I guess I¡¯ll give it another once over.

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

 

On 07/04/2019 09:32, Hans Summers wrote:
It would worry me that for every Huff Puff stabilizer kit sold, there'd be on average 10 emails back and forth about how to connect it to this or that piece of equipment which was designed a decade or few before I was even born...
Am I being too pessimistic?
Hans,

Probably not. This sort of thing does have to be adjusted and interfaced to a particular radio. I could not build a stable VFO so used one of the PA0KSB design in a converted Decca Voyager, surplus many years ago. Maybe you had just been born.. but the radio was definitely designed long before that.
I do not think the Huff-puff was a kit but if it were it would really be best built by someone who did not need it to be. I mean someone who is happy experimenting. I'm sure I spent many frustrating hours getting it right.
In any case would such a kit really sell much? As mentioned there are many modern VFOs that with ingenuity would give better results.

73 Alan G4ZFQ
Re: Qrp-labs and a Huff and Puff circuit board

 

Henning,? this s something which deserves a photo!? or two.? It is a fascinating bit of history actually this whole huff'n'puff subject.? Hans himself did something very unorthadox but cool, in using a magnetic field created by current flow in a relay coil next to the VFO inductor to effect control of the VFO frequency by external magnetic coupling.? That was a clever way to isolate the control output from the reciever to avoid ground loops.? The X-lock used optocouplers.? The discrete hufnpuffs using delay logic and XOR gates can operate very vast but this introduces phase jitter which can broaden the spectral fingerprint of the local oscillator in multiples of the sampling clock for the phase measurement.? One of the later approaches to this used a PIC processor to do both the signal delay and XOR function in software which reduces parts count I thought was very interesting. If anybody is looking for source code (PIC assembler) for any of these let me know via PM and I can give it to you.? I have ported many of these from PIC16 to PIC18. I prefer to avoid the high refresh rate of this type of control technique? for something which measures the frequency and controls its isolated output only a few times per second.? This should keep the spectral purity of the local oscillator much narrower.

Best regards
Joe


On Sun, Apr 7, 2019 at 2:57 PM Henning Weddig via Groups.Io <hweddig=[email protected]> wrote:
All,
the second Version Arv mentioned reminds me to my Version which I build in 1972/1973? together with a frind of mine using TTL chips: a frequency counter using 7490 Chips + 7575 latches connected to a set of magnitude comparators 7485, plus a "prescaler subtracting the IF of 460 kHz. The wanted freqeuncy was Input via another set of latches which were driven by "Touch Input"? and a decimal to BCD decoder.
The outputs of the magnitude comparators triggered two 74121 monoflops which then charged or discharged a "big" electrolythic cap (1000 uF) The Radio was a "modified" portable (Nordmende Globetrotter) using a varicap insteead of the tuning cap.? We could receive shortwave Radio stations up to the 19 m band (set by the Radio).The receiving frequency was displayed using NIXIE tubes. At least I included a "sort of Punch Card Reader using some bulb lights and LDRs plus circuitry to convert this to TTL Levels.
The unit still exists--- but never "fired" on again.
We won second place plus an extra Prize in the "science fair" ("Jugend forscht") in? Germany im May 1973.....?
Henning Weddig
DK5LV
?

-----Urspr¨¹ngliche Mitteilung-----
Von: Arv Evans <arvid.evans@...>
An: QRPLabs <[email protected]>
Verschickt: So, 7. Apr. 2019 18:19
Betreff: Re: [QRPLabs] Qrp-labs and a Huff and Puff circuit board

Hans and Mike

I would encourage Mike to try building his own H&P frequency stabilizer.? Initial look at
the design may seem a bit overwhelming for such a trivial circuit, but it really is not
that difficult.? You need a stable LF reference clock.? This can be a divided-down crystal
oscillator, or can be the VFO itself divided down to LF and compared with a high-frequency
oscillator.? It works either way.? Key to H&P operation is edge comparison of an LF reference
signal with a higher HF signal.? If the HF edge leads the reference edge then add variable C
to lower frequency.? If it lags the reference then decrease C to raise the frequency.? There is
no lock state.? It is always hovering within a cycle or two of some multiple of the reference
frequency.? The LF reference sets the tuning step size so it will probably be in the 20 to 60
Hz range. ?

All this can be done with just a few components.? Hans famously designed? minimalist
H&P circuits that have been popular for a number of years.?

http://www.hanssummers.com/huffpuff/minimalist/1chip.html

http://www.hanssummers.com/huffpuff/minimalist/2chipfast.html

If your rig includes an Arduino board (or an AVR microprocessor) there may be another
way to do H&P-like stabilization and general tuning.? This would involve a pre-scaler
(74HC74...?) to lower the HF oscillator signal to where the AVR could count it reliably.?
The operator would use push-buttons to set a desired frequency in the AVR memory.
The AVR would count frequency and compare it with the registered value and add or
subtract C to bring the HF oscillator into match with the register value.? This is not H&P
but would work something like it.?

Sometimes we may be quick to criticize what another person wants to do.? Maybe we
should be encouraging them to experiment, learn, and contribute their experience
back to the ham radio community.?

Arv
_._


On Sun, Apr 7, 2019 at 3:32 AM Hans Summers <hans.summers@...> wrote:
Hi Mike

I love Huff Puff circuits. There's no doubt though, this technique is practically-speaking outdated now it is so easy to generate clean stable signals so cheaply with chips like the Si5351A.?

But that is not the only problem...?

The big problem with Huff Puff is the interface to the VFO being stabilized. Two interfaces in fact. Firstly the Huff Puff circuit needs to measure the frequency coming out of the VFO. You need a circuit that will convert whatever signal comes out of the VFO, into a 5V pulse for the Huff Puff circuit. Then the correction signal coming out of the Huff Puff circuit has to somehow be able to steer the VFO frequency. Which typically means a varicap/varactor diode. But how that is connected to the VFO and what frequency control range you decide on, depends on the type of circuit you're fitting it to. There's probably almost as many answers to these questions as there are models of equipment people may wish to use it with. Even at the best of times it requires some considerable amount of experimenting to get it all working sweetly...?

In one view, a kit in some way needs to be something repeatable, something people can build according to a prescriptive recipe. It would worry me that for every Huff Puff stabilizer kit sold, there'd be on average 10 emails back and forth about how to connect it to this or that piece of equipment which was designed a decade or few before I was even born...?

Am I being too pessimistic??

73 Hans G0UPL?
http://qrp-labs.com?

On Fri, Apr 5, 2019, 19:59 Mike Donovan <mdon01@...> wrote:
Any chance Hans, or someone else associated here of making a modern Huff and Puff kit for installation in older rigs using PTO ie Tentec rigs, Drake rigs, Swan....etc. ? Since there is no available units on the market, I thought I would ask

Mike Donovan. VE7EPQ?

Re: Strange audio issue #qcx

 

I agree, but I¡¯ve checked it and checked it. I guess I¡¯ll give it another once over.
Re: Strange audio issue #qcx

 

¿ªÔÆÌåÓý

Hi Rob
?
Just looked at the Bamatech case and it looks like there is loads of room around the headphone connector, so guess that's not the problem, coincidentally the case is almost the same as the one I use but mine has a sloping top panel.
?
Good Luck
?
Ian G4GIR
?

From: KT4RK
Sent: Sunday, April 7, 2019 7:30 PM
Subject: Re: [QRPLabs] Strange audio issue #qcx
?
Yes, it¡¯s in the Bamatech metal case.?

Re: Strange audio issue #qcx

 

Sometimes I find my QCX is ¡°deaf¡± on receive and it requires me to tap the side of the rig to get it to ¡°hear¡± signals. I also notice that tapping on the case gives a loud sound in my earphones and I also get a similar loud pop when I press the buttons. I¡¯ve checked for loose connections and can¡¯t find anything.
Thoughts?
Rob,

Seems obvious, although not obvious.
Must be a bad connection, solder joint, fragment of wire/solder, something shorting together or on the metal? case..

73 Alan G4ZFQ
Re: Strange audio issue #qcx

 

¿ªÔÆÌåÓý

Hi Rob
?
Well my problem was that I got a crackle/scrathcy noise in the headphones as I pressed a button turned a knob or moved the antennae cable at the BNC socket.
I never had it go deaf though.
?
I don¡¯t know the Bamatech case but will check it out.
?
My QCX¡¯s are built into a case that I had to drill machine etc to suit all the sockets pots and bits.
The problem was that the hole in the right hand side of the case where the headphone socket protruded was only a few thou larger than the metal ring on the headphone socket.
?
That ring doesn't appear to be grounded, so when ever the case touched the ring it induced the noise in the headphones.
?
I got over the problem by increasing the hole size so it couldn't touch the case.
?
I had this problem with 2 of my 3 QCX¡¯s. The good one was a larger hole!!
?
Hope this may help you.
?
73
?
Ian G4GIR

From: KT4RK
Sent: Sunday, April 7, 2019 7:30 PM
Subject: Re: [QRPLabs] Strange audio issue #qcx
?
Yes, it¡¯s in the Bamatech metal case.?

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

 

All,
the second Version Arv mentioned reminds me to my Version which I build in 1972/1973? together with a frind of mine using TTL chips: a frequency counter using 7490 Chips + 7575 latches connected to a set of magnitude comparators 7485, plus a "prescaler subtracting the IF of 460 kHz. The wanted freqeuncy was Input via another set of latches which were driven by "Touch Input"? and a decimal to BCD decoder.
The outputs of the magnitude comparators triggered two 74121 monoflops which then charged or discharged a "big" electrolythic cap (1000 uF) The Radio was a "modified" portable (Nordmende Globetrotter) using a varicap insteead of the tuning cap.? We could receive shortwave Radio stations up to the 19 m band (set by the Radio).The receiving frequency was displayed using NIXIE tubes. At least I included a "sort of Punch Card Reader using some bulb lights and LDRs plus circuitry to convert this to TTL Levels.
The unit still exists--- but never "fired" on again.
We won second place plus an extra Prize in the "science fair" ("Jugend forscht") in? Germany im May 1973.....?
Henning Weddig
DK5LV
?

-----Urspr¨¹ngliche Mitteilung-----
Von: Arv Evans <arvid.evans@...>
An: QRPLabs <[email protected]>
Verschickt: So, 7. Apr. 2019 18:19
Betreff: Re: [QRPLabs] Qrp-labs and a Huff and Puff circuit board

Hans and Mike

I would encourage Mike to try building his own H&P frequency stabilizer.? Initial look at
the design may seem a bit overwhelming for such a trivial circuit, but it really is not
that difficult.? You need a stable LF reference clock.? This can be a divided-down crystal
oscillator, or can be the VFO itself divided down to LF and compared with a high-frequency
oscillator.? It works either way.? Key to H&P operation is edge comparison of an LF reference
signal with a higher HF signal.? If the HF edge leads the reference edge then add variable C
to lower frequency.? If it lags the reference then decrease C to raise the frequency.? There is
no lock state.? It is always hovering within a cycle or two of some multiple of the reference
frequency.? The LF reference sets the tuning step size so it will probably be in the 20 to 60
Hz range. ?

All this can be done with just a few components.? Hans famously designed? minimalist
H&P circuits that have been popular for a number of years.?

http://www.hanssummers.com/huffpuff/minimalist/1chip.html

http://www.hanssummers.com/huffpuff/minimalist/2chipfast.html

If your rig includes an Arduino board (or an AVR microprocessor) there may be another
way to do H&P-like stabilization and general tuning.? This would involve a pre-scaler
(74HC74...?) to lower the HF oscillator signal to where the AVR could count it reliably.?
The operator would use push-buttons to set a desired frequency in the AVR memory.
The AVR would count frequency and compare it with the registered value and add or
subtract C to bring the HF oscillator into match with the register value.? This is not H&P
but would work something like it.?

Sometimes we may be quick to criticize what another person wants to do.? Maybe we
should be encouraging them to experiment, learn, and contribute their experience
back to the ham radio community.?

Arv
_._


On Sun, Apr 7, 2019 at 3:32 AM Hans Summers <hans.summers@...> wrote:

Hi Mike

I love Huff Puff circuits. There's no doubt though, this technique is practically-speaking outdated now it is so easy to generate clean stable signals so cheaply with chips like the Si5351A.?

But that is not the only problem...?

The big problem with Huff Puff is the interface to the VFO being stabilized. Two interfaces in fact. Firstly the Huff Puff circuit needs to measure the frequency coming out of the VFO. You need a circuit that will convert whatever signal comes out of the VFO, into a 5V pulse for the Huff Puff circuit. Then the correction signal coming out of the Huff Puff circuit has to somehow be able to steer the VFO frequency. Which typically means a varicap/varactor diode. But how that is connected to the VFO and what frequency control range you decide on, depends on the type of circuit you're fitting it to. There's probably almost as many answers to these questions as there are models of equipment people may wish to use it with. Even at the best of times it requires some considerable amount of experimenting to get it all working sweetly...?

In one view, a kit in some way needs to be something repeatable, something people can build according to a prescriptive recipe. It would worry me that for every Huff Puff stabilizer kit sold, there'd be on average 10 emails back and forth about how to connect it to this or that piece of equipment which was designed a decade or few before I was even born...?

Am I being too pessimistic??

73 Hans G0UPL?

On Fri, Apr 5, 2019, 19:59 Mike Donovan <mdon01@...> wrote:
Any chance Hans, or someone else associated here of making a modern Huff and Puff kit for installation in older rigs using PTO ie Tentec rigs, Drake rigs, Swan....etc. ? Since there is no available units on the market, I thought I would ask

Mike Donovan. VE7EPQ?

Re: 20m QCX RF Output Question #qcx

 

I installed new caps, removed turns from L1, L2, and L3. I checked the voltages on the IC chip (IC3 I things). Never did figure it out. Based on the other input I¡¯ve received, I¡¯m just leaving well enough alone and going with the 2.29 watts I have. The only downside is that I¡¯m getting less than a watt using a 9 volt battery.?

I finished my QCX-20 with a small mod that incorporated a momentary switch I had in my parts box to the panel of my enclosure so I could retain the straight key feature.?

Thanks to to everyone who took time to help out.?
Re: Strange audio issue #qcx

 

Yes, it¡¯s in the Bamatech metal case.?
Re: Strange audio issue #qcx

 

¿ªÔÆÌåÓý

Hi Rob
?
Is your QCX in a metal case? If so I may be able to shed some light as I had similar experiences, If it is not in a metal case then I don't have any solution for you!
?
Cheers
?
Ian G4GIR
?

From: KT4RK
Sent: Sunday, April 7, 2019 7:00 PM
Subject: [QRPLabs] Strange audio issue #qcx
?
Based upon advice from many helpful folks here, I decided to leave well enough alone on the low power issue and I have my QCX ready to go with a minor modification that added a momentary switch to the top of the case for use as a straight key. I have found one more problem that I¡¯m not sure about.

Sometimes I find my QCX is ¡°deaf¡± on receive and it requires me to tap the side of the rig to get it to ¡°hear¡± signals. I also notice that tapping on the case gives a loud sound in my earphones and I also get a similar loud pop when I press the buttons. I¡¯ve checked for loose connections and can¡¯t find anything.

Thoughts? Thanks!

Rob KT4RK?

WOOHOO ! My first 20m CW QSO using the QCX-17 is in the log !

n4qa at_hotmail.com
 

Many thanks to Greg, W7GA, for pulling my QRP sigs out of the mud on 14062 kHz, using my QCX-17 xcvr with external freq control...and external filtering :0)
72 / 73,
Bill, N4QA
Re: Keyer issue. #problem

 

I had problems when I ran it on iambic A, but finds mine works fine on iambic B. Not sure if that helps.
Re: Qrp-labs and a Huff and Puff circuit board

 

No Hans I think you are being quite a realist in your comment about a huff'n'puff kit.? Afterall there is a reason that Cumbria Designs no longer sells the X-Lock kit which I now wish to essentially duplicate.? Each application needs the interfaces to be specific and probably different.? It would be a headache for a kit producer and since it is only a few odballs like me who want one for some atypical need it wouldn't return much $$ for all the effort to produce and support it.? However for us few nutbars we will gladly make our own.? There are plenty of reference designs out there to learn from.? I've no doubt I can get good stability with this frequency counter approach, I am less sure I can keep the processor asleep for long enough that the average current draw will only be a few mA.

Best regards
Joe ve3vxo


On Sun, Apr 7, 2019 at 5:32 AM Hans Summers <hans.summers@...> wrote:
Hi Mike

I love Huff Puff circuits. There's no doubt though, this technique is practically-speaking outdated now it is so easy to generate clean stable signals so cheaply with chips like the Si5351A.?

But that is not the only problem...?

The big problem with Huff Puff is the interface to the VFO being stabilized. Two interfaces in fact. Firstly the Huff Puff circuit needs to measure the frequency coming out of the VFO. You need a circuit that will convert whatever signal comes out of the VFO, into a 5V pulse for the Huff Puff circuit. Then the correction signal coming out of the Huff Puff circuit has to somehow be able to steer the VFO frequency. Which typically means a varicap/varactor diode. But how that is connected to the VFO and what frequency control range you decide on, depends on the type of circuit you're fitting it to. There's probably almost as many answers to these questions as there are models of equipment people may wish to use it with. Even at the best of times it requires some considerable amount of experimenting to get it all working sweetly...?

In one view, a kit in some way needs to be something repeatable, something people can build according to a prescriptive recipe. It would worry me that for every Huff Puff stabilizer kit sold, there'd be on average 10 emails back and forth about how to connect it to this or that piece of equipment which was designed a decade or few before I was even born...?

Am I being too pessimistic??

73 Hans G0UPL?
?

On Fri, Apr 5, 2019, 19:59 Mike Donovan <mdon01@...> wrote:
Any chance Hans, or someone else associated here of making a modern Huff and Puff kit for installation in older rigs using PTO ie Tentec rigs, Drake rigs, Swan....etc. ? Since there is no available units on the market, I thought I would ask

Mike Donovan. VE7EPQ?

Strange audio issue #qcx

 

Based upon advice from many helpful folks here, I decided to leave well enough alone on the low power issue and I have my QCX ready to go with a minor modification that added a momentary switch to the top of the case for use as a straight key. I have found one more problem that I¡¯m not sure about.

Sometimes I find my QCX is ¡°deaf¡± on receive and it requires me to tap the side of the rig to get it to ¡°hear¡± signals. I also notice that tapping on the case gives a loud sound in my earphones and I also get a similar loud pop when I press the buttons. I¡¯ve checked for loose connections and can¡¯t find anything.?

Thoughts? Thanks!

Rob KT4RK?
Now looking for a 20m CW Q on my QCX-17

n4qa at_hotmail.com
 

Plenty of FT8 sigs...even a few JS8 sigs on 20m right now using the QCX-17.
The attached screen shot shows my 'app' ;0) and RBN spots of the QCX-80 and QCX-17 under external freq control.
BTW, some RBN skimmers are more freq-accurate than others...
Oh, and, I'm using appropriate filtering of the QCX's xmtr output...

72 / 73,
Bill, N4QA
Re: QCX 40 Woes

n4qa at_hotmail.com
 

Hi Mike.
I get that a lot when my rig, PC etc try to become part of my antenna system, especially when using an external 'amplified speaker'.
Could you describe your antenna & feedline...and any audio processing components.
72 /73,
Bill, N4QA
Re: Qrp-labs and a Huff and Puff circuit board

 

Hahaha yeah Bill you're right.? But did you notice my callsign?? A PTO is a new game for the kid after all the vxo stuff gets old.

Joe -VE3VXO


On Sat, Apr 6, 2019 at 8:20 PM Bill Cromwell <wrcromwell@...> wrote:
Hi Joe,

If you are concerned about current drain, drift, AND phase noise you
might consider a VXO. Obviously it won't tune from DC to daylight. So
many choices, -sigh-

73,

Bill? KU8H

On 4/6/19 7:03 PM, Joe Street wrote:
> Hi Allison
>
> All good points, however consider in the context, this is a PTO I am
> building for my Norcal 2030, a rig which has phenomenal dynamic range
> and large close in signal handling while sipping only 11mA of current
> from 12 volts!? Such an energy efficient design with such stellar
> performance begs to be taken out on field day, maybe somewhere far away
> where weight and battery life are important.? I wouldn't want to ruin
> the power efficiency with any kind of synth.? Also the phase noise of
> the PTO will be better than a synth and phase noise of the local
> oscillator is a factor in the large signal performance.? I'm trying to
> make this rig suitable for a changing temperature environment without
> ruining it.? I looked at fast huffnpuffs but fear these will have a
> negative affect on phase noise so I am now only considering the type
> that make a small correction no more frequently than a few times per
> second.? I hope I can make it work and not add more than a few mA to the
> overall current draw.? I will make it so it can be turned off as well if
> need be.
>
> Joe ve3vxo
>
> On Sat, Apr 6, 2019 at 6:23 PM ajparent1/KB1GMX <kb1gmx@...
> <mailto:kb1gmx@...>> wrote:
>
>? ? ?Generally with PTO radios of the tentec and Drake realm if the PTO
>? ? ?is drifting something
>? ? ?isn't right.? I start there.
>
>? ? ?Exceptions are Swan and Atlas plus a few older Tentec like the
>? ? ?Argonaut 505 and 509 as
>? ? ?they use a fairly high frequency PTO for some bands.? It doesn't
>? ? ?solve the problem of
>? ? ?dial calibration or drifting for narrow modes like JT8 or even PSK31.
>
>? ? ?Rather than going the huff&puff I just drop in a DDS or 5351 and
>? ? ?kill the problem cold.
>? ? ?The only one I've resorted to for that is one junker level Atlas 210
>? ? ?and that vfo was
>? ? ?not savable due to 11M mods the rig was subjected to.
>
>? ? ?Allison
>
>

--
bark less - wag more
QCX 40 Woes

 

Just finished my QCX 40 kit and it went together well. Came right up with good alignment and output at 12-16v. Problem is cw sounds terrible through the headphones/speaker. I get a loud click at the beginning and end with about a one second delay on semi-qsk. There is no sideband on anything above 20wpm on full qsk.Rechecked output and alignment which is good. Kinda stumped at this point.
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