Monday, 12 October 2009

HB-1A QSK delay

There is a hardware method to extend the qsk delay but I wonder as the keyer is separate from the main control PIC if it might be possible to alter the timing of MUTE signal from pin 6 of the Keyer PIC (12F629) (or the main PIC (16F73) pin RB6) if, and that is the key, no pun intended, the asm became available to do this. That both are F types and not C types means they could be reprogrammed, although in circut programming support does not exist that would mean removal for reprogramming. But both are non SMD devices.
That said as the keyer PIC is separate from the main control PIC and the button S3 (CQ/SET) is used for the CW CQ message I suspect another option might be to roll your own keyer. I wonder if there is enough PCB 'space' to use a small daughter board and say SMD PIC16F628 if so then a lot of the 16F628 keyers out there (code and pin number dependant obviously) might be possible.

Maybe other possible keyer chips might be used?

4 comments:

N1RX said...

Looking at the HB-1A3 rev 2009-08-05 schematic, it would appear that increasing the value of one capacitor in the mute circuit, and adding another would accomplish this. C19 is now 0.1 uF. Increasing this one, and adding one from the base of Q12 to ground of similar value would result in a slower return of RX audio, if that is your goal. I would probably start by doubling the value, by paralleling another 0.1 uf across C19, and possibly adding a 0.1-0.22 at the base of Q12.

One of the things I will probably do eventually is completely replace the keyer chip with a more capable one (like the Picokeyer by N0XAS). Unfortunately, every other keyer chip I have looked at so far uses the pins differently. This means that modifications will have to be made to the PC board to do this.

I will save this mod for later, but I will do it eventually. 73, Bruce N1RX (waiting for my kit to arrive)

M1KTA said...

Bruce,

Thanks for comment.

I am wondering about this with two maybe three options:

if a little 8pin dil daughter board might be used then you could build a SMD version of the N0XS et al keyer with the correct pins.... or obtain the code and chnage the in/out pins to maych those used with HB-1A.

Dom

N1RX said...

HI Dom.

Agreed that using a small DIL daughterboard would avoid having to modify the board. That is certainly an option, if the substituted keyer chip is available in SMD. I just started looking over other keyers based on the 12F629 that I am familiar with. None of them are either available in SMD, or have opensource code. That's the reason for my initial suggestion that board modification may be the "easiest" way to get a more capable keyer unit in there.

There are always options, however... 8-). -Bruce

M1KTA said...

Bruce,

I think given might not be easy to modify the board directly a daughter board might be an easier way to go. As for SMD I meant but didn't say it... using perhaps a PIC16F628 or similar. These are available in SOIC/SSOP and QFN packages too. That way there might be lots of alternative keyer options, the DL4YHF for instance http://freenet-homepage.de/dl4yhf/key_circ.html. BTW I have asked Dale (N0XAS) if it might be possible to recode, bespoke as it were the PicoKeyer for this pin config, if it is then you might be able to just drop it in as a replacement.

Of course if the HB-1A PIC12F629 source were available recoding the keyer might be easier?

Bit off topic but current frequency coverage, I spoke with Martin Lynch at RSGB 2009 Convention this week end where they were selling the imported built radios and I said thought 80m might for the UK anyway be a good addition or become 80m, 40m, 20m, that would be pa and LPF/BPF dependant of course.

72
Dom
M1KTA