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

?

-----Ursprüngliche 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?