[Elecraft] FW: K3: CW in SSB mode broken?

[Oliver Dröse]

Hi Don,

indeed one of the sequencer outputs could also be applied to the TX-INH pin. 
When we first designed the FA station manager I did not have my K3 yet so 
did not know much about TX-INH (and never thought about that on my old Yaesu 
radios, hi). Besides the solution should be usable with *any* available 
transceiver that's why we chose to go for PTT (or to be more precise: 
MIC-PTT, Digimode-PTT and CW, depending on the trigger).

Yes, TX-INH is quite comfortable as you can still use the K3's internal 
voice/cw-keyer and do not need to use some external devices before the 
sequencer. One of the reasons I designed (and use it myself) another 
sequencer exclusively for K3 use (including the needed pull-up, etc.). But 
that only works reasonably well as long as the switching times of LNA/PA are 
not too high as you will loose/truncate the first cw signs when you need 
higher switching delays (and thus need to prevent K3 output using TX-INH for 
longer time then the first cw sign needs). Then it would be better again to 
use the FA-SM with it's built-in CW buffer that will just send the dits and 
dahs after everything has switched.

But well, isn't it nice to have choices? ;-))

Vy 73, Olli - DH8BQA
http://www.dh8bqa.de/

PS: Also see my comment in my reply to Joe - thanks for your great knowledge 
sharing, guys! :-))




----- Original Message ----- 
From: "Don Wilhelm" <w3fpr at embarqmail.com>
To: "Oliver Dröse" <droese at necg.de>
Cc: <elecraft at mailman.qth.net>
Sent: Friday, February 03, 2012 1:53 AM
Subject: Re: [Elecraft] FW: K3: CW in SSB mode broken?


> Olli,
>
> While your intention may have been for PTT use, and your documentation may 
> be directed at PTT, the output from the sequencer is effectively an open 
> circuit (sequence not complete) or a circuit closure (sequence complete). 
> That is simply a signal - it can be applied to the K3 TX INH input just as 
> easily as being applied to the K3 PTT.
>
> If you have an example of how your sequencer output is better applied to 
> PTT than to TX INH, please tell us.  IMHO, the use of TX INH offers a much 
> greater range of control over the switching events and the emission of RF 
> from the K3.
>
> 73,
> Don W3FPR
>
> On 2/2/2012 7:17 PM, Oliver Dröse wrote:
>>> While it might be possible to modify control to allow CW in SSB with
>>> PTT if PTT and CW were activated at the very same instant (by adding
>>> diodes from key in, dit in and dah in to PTT In), that would not fix
>>> your issue with a sequencer since the sequencer (and foot switch) will
>>> generally set PTT some fraction of a second *before* CW in any case.
>> Well, it actually depends on the sequencer, I'd say. ;-))
>>
>> Within the "FA station manager" 
>> (http://www.dh8bqa.de/fa-sm/fa-sm-en.html) I
>> designed the sequencer to only switch input trigger = output trigger. 
>> That
>> means if you trigger the sequencer by PTT (i.e. from the mic) it will 
>> switch
>> all stages for pre-amp, amp, etc. and then PTT to TRX as the last stage. 
>> If
>> the trigger is CW then it will switch all stages for pre-amp, amp, etc. 
>> but
>> *not* PTT to TRX but just opens the CW interlock to TRX so the radio will
>> not see a PTT signal, only the CW signal. Therefor CW in SSB with the K3
>> works perfectly well even using a sequencer. ;-))
>>
>> Nevertheless using TX-INH is probably the easier solution for K3's that
>> already have a DVR built in (plus CW anyway). I've designed a solution 
>> for
>> that case, too, but not yet up on my website.
>>
>> Vy 73, Olli - DH8BQA
>> http://www.dh8bqa.de/
>>
>>
>>
>>
>>
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