K3 - qsk keying loop

[Barry N1EU]

K7GT obviously has the same concerns.  Over the past decade I've used
a slew of Ten-Tec and Yaesu xcvrs interfaced to Ten-Tec, Alpha, and
Acom amplifiers via plug 'n play keying loops with uniformly excellent
performance.

The lack of QRO QSK with the K3 may be a big issue with some
prospective K3 contesters.

73,
Barry N1EU


>Don, in the email below, says that the time delay in the K3 will accommodate
a QSK amp. That is only partially true. The problem is in setting it
up. I could,
of course, put in a LONG delay but then QSK is gone. If I crank the delay down,
at some point I am relying on the RF sensing circuitry in my QSK amps to hold
the relays closed until RF is really gone from the input. That may work but I
would really prefer the sure-fire solution of a keying loop. This allows a QSK
amp to be set up optimally by just plugging in and does not require a scope
and a bunch of fuss. The QSK of my Tentec transceivers coupled with
either the Titan or Hercules II QSK amps is plenty fast for me as I
never go above 50 wpm anyway.

>For what it is worth, the Yaesu transceivers and their Quadra QSK amp use a
keying loop. It works great also. We used it in SS this year and had a ball.

I> am sure that the K3 will key perfectly with the yet-to-be-available Elecraft
amps, but it would be nice if interfacing with existing QSK amps could be
done in the obvious way.
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[Eric Swartz - WA6HHQ]

Hi Barry,

There is a lot of confusion and mis-information about the need for CW
keying loop feedback from the amplifier to the rig in the amateur
community. While certainly it was necessary on some older rig and amp
combinations, it is not necessary with a properly designed rig today
that has sequenced amplifier key-out to RF output. As an example, I run
both my K2 and K3 in full break-in with my Alpha 87a amplifier with no
timing problems or reduction in break-in performance.  A large number of
our customers run full break-in with our rigs in this manner using a
wide range of full break-in amplifiers. There is no degradation of rig
break-in performance when using the K2 or K3 in this manner. A large
number of our K3 Field Testers are break-in CW ops with amplifiers and
none have had any issues with running our rigs with their amps.

I think that since some are used to using a keying feedback loop on
other rigs and amps that it is necessary on all. I guess I disagree :-)
. RF sensing in the AMP is absolutely not needed with proper key-out to
RF sequencing from the rig. And excessive delays are -not- needed.

But, if it can be shown that we actually can increase K3 break-in
performance with an amp by doing something like this, we'll certainly
look at doing it.

73, Eric   WA6HHQ

_..._

Barry N1EU wrote:

> K7GT obviously has the same concerns.  Over the past decade I've used
> a slew of Ten-Tec and Yaesu xcvrs interfaced to Ten-Tec, Alpha, and
> Acom amplifiers via plug 'n play keying loops with uniformly excellent
> performance.
>
> The lack of QRO QSK with the K3 may be a big issue with some
> prospective K3 contesters.
>
> 73,
> Barry N1EU
>
>
>  
>> Don, in the email below, says that the time delay in the K3 will accommodate
>>    
> a QSK amp. That is only partially true. The problem is in setting it
> up. I could,
> of course, put in a LONG delay but then QSK is gone. If I crank the delay down,
> at some point I am relying on the RF sensing circuitry in my QSK amps to hold
> the relays closed until RF is really gone from the input. That may work but I
> would really prefer the sure-fire solution of a keying loop. This allows a QSK
> amp to be set up optimally by just plugging in and does not require a scope
> and a bunch of fuss. The QSK of my Tentec transceivers coupled with
> either the Titan or Hercules II QSK amps is plenty fast for me as I
> never go above 50 wpm anyway.
>
>  
>>    

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[Ed Muns, W0YK]

> K7GT obviously has the same concerns.  Over the past decade
> I've used a slew of Ten-Tec and Yaesu xcvrs interfaced to
> Ten-Tec, Alpha, and Acom amplifiers via plug 'n play keying
> loops with uniformly excellent performance.
>
> The lack of QRO QSK with the K3 may be a big issue with some
> prospective K3 contesters.

Could be, although I've used Alpha 87As with each of my K3s in SS CW and
many other CW contests, full bore QSK, for four months now.  KEY OUT from
the K3 to the 87A has worked great, as far as I can tell.

73,
Ed - W0YK

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[Vic K2VCO]

Barry N1EU wrote:
> K7GT obviously has the same concerns.  Over the past decade I've used
> a slew of Ten-Tec and Yaesu xcvrs interfaced to Ten-Tec, Alpha, and
> Acom amplifiers via plug 'n play keying loops with uniformly excellent
> performance.

There is a delay built into the K3's amplifier keying output, both
before RF is produced and after it stops. Perhaps all Elecraft needs to
do is publish this specification and it will be possible for you to feel
more comfortable. I have used the K2, which has about 15 ms pre-RF delay
  and adjustable after-RF hold with homebrew and modified amplifiers
that use vacuum relays as well as an Alpha with PIN diodes, and in all
cases there has been no hot switching (checked with a scope).

The K3's "semi-QSK" setting allows you to adjust the hold time from the
same as "full QSK" to a much longer delay than you will need. So as long
as the pre-RF delay is long enough, you should have no problems.

In my opinion, keying loops add unnecessary complication.
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco
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