ELecraft K2 DATA port IMPORTANT update

[Jean-François Ménard-5]

Hi everybody,

Since my first prototype of the K2 DATA port implementation, I did some
extensive test today during an outdoor portable operation.

I found that ground loop can occur on lower band... 40m or lower... And the
problem come from the PTT line.... that goes to ground during TX. Even if
the line IN and OUT are both isolated with an audio tranformer.

I also test today my DATA port with my SCS PTC-IIe modem and had the same
problem.

I finally found the problem and solved it !!

Like SCS (PTC-IIe manufactuer) said in their user manual. If you tranceiver
have an external power option, like found on Yaesu FT-8XX data connector,
YOU SHOULD USE IT. Do not power your modem from another power source, but
from the transceiver port itself. Like for the NUE-PSK, PTC-IIe or any other
TNC... always power your device with power from your transceiver.

This way, you will avoid ground loop that will harm your signal quality for
sure.

I just add one wire inside my K2 to the DATA port. I took the 12V line from
the AUX 12V connector inside the K2. This way, you will not have any more
problem and finally have an universal DATA port ffor almost any kind of
external device.

I will post a revised schematic on my website this week.

Like my previous modification, I always use RG-174 for inside wires. It does
prevent RF pickup during transmit and keep the signal as clean as possible.

I will also post a few more pics.

Another tip, apply acrylic coating spray on the back of the amplifier board
before applying the two way tape. It will prevent short circuit with any
electronic part with the chassis.

Best 73,

de J-F VA2SS
===

de J-F VA2SS

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[w7aqk]

I have used the Palm paddles, and many other small sized paddles.  In fact, I brought my Palm paddle with me on this weekend's trip to Ozarkcon.  The Palm is well made, and fairly easy to use.  But like almost all small paddles, it has issues.  For one thing, like most small paddles the Palm is very hard to secure or hold firmly because it is so small.  It's just hard to find a good place to hold on and stabilize it while you send.  But it's easier than some because it's longer, and you can hold it without interfering with the mechanism itself.  The levers feel a bit mushy to me, but again that's what you get with many smaller paddles.  What I like most about the Palm is that it seems very durable.  I like how it folds up for transport.  I don't think you will damage a Palm unless you really abuse it.  Overall, I'd say it's definitely one of the better small paddles.  

The small paddle that I like best for "feel" is the Porta-Paddle by American Morse.  It's also well made and durable.  It's a little harder to secure comfortably, but maybe you won't find it as difficult to do as I seem to.  The mechanism is fairly simple, but effective.  And I like the way it looks.  My version of this is one of the older, original ones Doug Hauff made some years ago.  It looks much the same as those sold currently, but not exactly.  But I've handled a newer one, and it feels much the same.  

I'm still looking for the "ideal" small paddle, but until I find it, I'll take one of the above.

Dave W7AQK




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[Mike Fitzgibbon]

I have a set of these and, for a base, had my kid cut a piece of steel
out of 10/12 gage sheet that is slightly larger than the paddle
base...rounded the corners a bit with a sander and it holds down well
with the magnets.  I do, however, set my paddles for a very light
touch...  I'm sure any metal shop could cut a base for a small
compensation...

I had the early model Paddletts(sp?) with the springy brass arms and
thought they were nasty...the newer ones are maybe better, but the
original ones were kinda lame...in more ways than one...

    Fitz  N0MF


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[Don Wilhelm-4]

Jean-Francios,

Congratulations on identifying and resolving the ground loop problem.

For those situations where a separate power supply is either required or
desirable, the use of an optoisolator instead of the more simple
transistor PTT/KEYING arrangement can also cure the ground loop
problem.  However, one must be careful not to unintentionally power the
optoisolator in such a way to make that 'sneaky' gound loop path
re-appear.  In most cases, the optoisolator should be powered from the
same supply that powers the device on the 'transistor' side of the
optoisolator.

73,
Don W3FPR

Jean-François Ménard wrote:

> Hi everybody,
>
> Since my first prototype of the K2 DATA port implementation, I did
> some extensive test today during an outdoor portable operation.
>
> I found that ground loop can occur on lower band... 40m or lower...
> And the problem come from the PTT line.... that goes to ground during
> TX. Even if the line IN and OUT are both isolated with an audio
> tranformer.
>
> I also test today my DATA port with my SCS PTC-IIe modem and had the
> same problem.
>
> I finally found the problem and solved it !!
>
> Like SCS (PTC-IIe manufactuer) said in their user manual. If you
> tranceiver have an external power option, like found on Yaesu FT-8XX
> data connector, YOU SHOULD USE IT. Do not power your modem from
> another power source, but from the transceiver port itself. Like for
> the NUE-PSK, PTC-IIe or any other TNC... always power your device with
> power from your transceiver.
>
> This way, you will avoid ground loop that will harm your signal
> quality for sure.
>
> I just add one wire inside my K2 to the DATA port. I took the 12V line
> from the AUX 12V connector inside the K2. This way, you will not have
> any more problem and finally have an universal DATA port ffor almost
> any kind of external device.
>
> I will post a revised schematic on my website this week.
>
> Like my previous modification, I always use RG-174 for inside wires.
> It does prevent RF pickup during transmit and keep the signal as clean
> as possible.
>
> I will also post a few more pics.
>
> Another tip, apply acrylic coating spray on the back of the amplifier
> board before applying the two way tape. It will prevent short circuit
> with any electronic part with the chassis.
>
> Best 73,
>
> de J-F VA2SS
> ===
>

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