Circuit variations WA1QIX vs KD1J O-C / PTT board

diagrams and such...

Circuit variations WA1QIX vs KD1J O-C / PTT board

Postby Glenn K2KL » Mon Feb 24, 2003 12:22 pm

Hi Folks;

I'm still busy collecting parts and have just received my PC board set from Kevin KD1J. Included with the boards are schematics drawn by Kevin. I'm sure I'm not the first one to notice differences from Steve's original schematics to the one's from Kevin. :?

The most obvious are the differences on the Over Current/PTT schematics.
Last night during a QSO on 75m, Brent and I were discussing the overload sensitivity trim-pot which is shown on Kevin's schematic as "R2" "1K"
On Steve's original schematic that pot is shown as a 100ohm. Fortunately Steve was on freq and commented that the pot should in fact be a 100ohm trim pot.

Some other observations and questions... :?:

The overload reset button, is it Normally open or normally closed?. Steve's schematic shows it as normally open, Kevin's normally closed.

Steve is using a combination of 110v and 12v coil relays where Kevin is using all 24v relays, not a big deal but since I'd also like to use the 110v ac PTT switching line presently on my dowkey changeover relay, Steve's arrangement will be more practical for my setup. If you use Steve's arrangement, you can power the two (12v) relays on the OC/PTT board from the ground referenced +/- 12v supply board/circuit. Kevin's arrangement will require an additional 24v supply source.

Please check me out on the following... (Steve? Kevin?)

If you want to use Kevin's PC board but with Steve's voltage/relay/switching setup you would.....

1) Connect your the 110v PTT line to the "24VDC Relay Supply" pins as marked on Kevin's schematic ??

2) Connect +12 from the Ground referenced supply to "D3" instead of "+24v" as marked on Kevin's schematic??

3) Use 12v coil relays instead of 24v relays on Kevin's pc board.

It appears, even if you do all this, you still need to provide an additional PTT contact closure at the point on Kevin's schematic marked "To PTT switch" in addition to the 110v PTT line on Steve's arrangement. :cry:

Now that I've confused myself and probably others, maybe this will open up some discussion and clarification.. :lol:
Glenn K2KL
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Schematic differences...

Postby Kevin » Mon Feb 24, 2003 6:22 pm

Hope I can enlighten you, Glenn, with some answers:

Use a 100 ohm Pot on the OC board- that 1K Pot was a leftover from
my early breadboarding. You'll notice I updated my schematic on
the website.

My Overload reset is NC. Allowed me to use one less relay in the
design. I show this on the supplied schematic.

Yes, I am using ALL 24 volt relays throughout. Of course you may
use other value relays, with matching coil supply voltages.

====

1) Connect your the 110v PTT line to the "24VDC Relay Supply" pins as marked on Kevin's schematic ??

You can connect ANY voltage here. They are just relay contacts.

====

2) Connect +12 from the Ground referenced supply to "D3" instead of "+24v" as marked on Kevin's schematic??

Yes. Whatever voltage relays you use on this board, that is the
value of voltage to supply at D3.

====

It appears, even if you do all this, you still need to provide an additional PTT contact closure at the point on Kevin's schematic marked "To PTT switch" in addition to the 110v PTT line on Steve's arrangement.

Not sure what you mean here. The PTT terminals on the board go to
my microphone PTT (NO) terminals.

====

Hope I've clarified all this for you, Glenn
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Re: Schematic differences...

Postby Glenn K2KL » Tue Feb 25, 2003 9:42 am

Thank you for taking the time to respond to my questions Kevin. After looking at the schematics again and reading your comments I realized most of my questions were pretty dumb! sorry 'bout that! :oops:

My comments about the trim-pot were based on the schematic you sent with the PC boards, I've since downloaded the latest drawing off your web site (did you mean to update the drawing rev to "B" ?)

Again, sorry for my confusion, on Steve's arrangement the PTT is acomplished by external switching of the 110v relay supply voltage. On your's the relay supply voltage source is always on and the PTT switching is done on your board through contact closure. I see!!! :D

Thanks for the help!!

PS... Your power supply panel looks fantastic! Lets see the insides when it's done! :)


Kevin wrote:Hope I can enlighten you, Glenn, with some answers:
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Schematic differences...

Postby Kevin » Tue Feb 25, 2003 10:26 am

OK, Glenn very good.

I guess the confusion was that I use 24 volts for relays, panel lamps etc...
everything, because thats what I had.

---

:!: One should be aware that the ground-referenced +12 volts supplied by
my Dual +/-12V board should not be used to power an endless string
of relays. It is not heat-sinked for >~200mA; enough to supply the
analog circuitry and the DIP relays on the OC/PTT board.

---

My project is not going very quickly. A lot of my hobby time has gone
into these PC Boards, of course. Hope to get something running
before the summertime activities de-rail me... 8)

I've always had more fun in the hobby "building rather than blabbing",
but I'll get this Class 'E' stuff up and running one day! :)
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Postby Glenn K2KL » Wed Feb 26, 2003 9:03 am

Hi Kevin;

Actually, you've got me thinking about using all 24v relays as well :lol:

I located some pretty heavy duty 24v relays in my junk box, to use for the four off-board power power supply relays, should make a pretty hearty "ker-chunk" when thrown into xmit! 8)

Since we want to go easy on the +/- 12 supply board regulators, and 24v transformers are a dime a dozen... :wink:

I'm always amazed at how a project can be driven by what's in your junk box!! :lol:
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