[Elecraft] K3 transmit/amplifier relay

[Scott Ellington]

If you look at sheet 1 of the RF Board schematic, you will see that Key Out is controlled by 7R, not 7T.   I'm pretty sure 7T is not the complement of 7R, as there are separate MCU outputs for them, T5 and R5.  This, no doubt, has to do with timing issues.  7R controls numerous switching diodes, so it just can't be disabled in PTT mode, or the monitor wouldn't even work.  AND, the MCU does not have a spare pin which could be used to gate Key Out.  So there is clearly no way a firmware change, even with a minor hardware change, can disable Key Out without also disabling the monitor, etc.  What firmware COULD do is completely disable transmit mode in PTT mode when the PTT switch is open.  That might be a useful option, but it wouldn't allow hearing the internal keyer in rx mode.

That's just the way it is.

73,

Scott  K9MA


On Mar 13, 2011, at 3:12 PM, Guy Olinger K2AV wrote:

> I am not so sure that this cannot be accomplished in firmware.
> 
> And I completely get what this causes if one has a complex pre-K3 setup
> switching tower-top preamps, etc., whose primary state-change signal comes
> from
> 
> Only the CPU knows that VOX is on or off.  There is no "VOX lead".  "Band
> down" and "VOX" share the same physical switch using "tap" and "hold".  The
> paddle states are interpreted in the CPU, there is no separate physical
> keyer circuitry.  Follow the /DASH or /DOT leads in the schematic and you
> will see it goes straight to the CPU.  Also there is no physical monitor
> oscillator which is keyed by 7T.
> 
> This gives me the firm gut estimate that firmware CAN clean this up.
> 
> HOWEVER...   And a BIG HOWEVER...
> 
> The same gut gestimates that the code that is touched is all over the place,
> would require a lot of testing because of everything that is involved, and
> therefore it goes on the priority list just like everything else, and
> weighted as "extensive".  And we want the big E to stay in business, so
> other development must go on.  Wayne might want to state whether this is on
> the list somewhere.  Then future queries can be answered: "It's on the
> list,"  and some day a firmware release will fix it.
> 
> BEYOND THAT, HOWEVER NUMBER TWO...
> 
> If the clanking relay while phantom sending is an issue, isn't the clanking
> relay in normal sending also an issue?  Don't blame the danging clanging
> relay on the K3.  Fix the $%&*(@!!@  AMP.  I modified all my amps with fast
> vacuum relays that are sound isolated by putting them on a blob of RTV.  End
> of the )()*(^%$##&*))!! clanging. For casual operating, I like to work
> without headphones, so the clanging is super-irritating.  The diversity is
> really pretty good through stereo speakers, even if not quite as "spread" as
> using headphones.
> 
> Since 99.999% of my operating is regular operation, the danging clanging
> (which I hate) is the AMP's problem.  Not the K3's.  For me that's a deal
> killer for some of the Alpha's.
> 
> 73, Guy.
> 
> 
> 
> On Sun, Mar 13, 2011 at 1:27 PM, Jim McCook <w6ya at cox.net> wrote:
> 
>> Ralph, VE7XF, took the words right from my own mouth.  This situation is
>> unique, extremely annoying, and I have not been able to get used to this
>> anomaly after several years.  Using my spare FT-1000D is a big relief in
>> that particular area.  I have asked for a solution to this for years,
>> but to no avail.
>> 
>> 73, Jim
>> W6YA
>> 
>> 
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Scott Ellington
Madison, Wisconsin
USA