[Elecraft] K2 K2 QSK?

[Don Wilhelm]

Jerry,

Your K2 #1 DOES have AGC - it is built into ALL K2s.
There are 2 possibilities - 1) the AGC has been turned off - that is a 2 
button function of PRE/ATT button and the AGC button pressed at the same 
time.  Normally just using the AGC button changes between FAST and SLOW.

2) The AGC threshold is not correct.  If the serial number is 3000 or 
above, there is a pot (R1 on the Control Board) to adjust the threshold 
- see the K2 manual for where to measure while setting it.

There are 2 VFOs in the K2 although only one is displayed at a time.  A 
simple tap of the A=B button will sync the 2 VFOs

It sounds like you  might benefit from downloading the K2 Quick 
Reference from my webpage www.w3fpr.com.  Look near the bottom of the 
homepage.  There is a lot more function to the K2 than meets the eye.

You will have to get the answer to your QSK on the K4 from someone else, 
but I expect it to be superb - I know both the K2 with the K2 Keying 
Waveshape Mod (SN 4660 and above) and the K3/K3S have excellent QSK 
keying, and I expect the same with the K4.

Unfortunately, the K2 Keying Waveshape Mod is not available from 
Elecraft, but Dave Van Wallaghen W8FGU was talking about providing a kit 
for it.  If your K2 does not have it, I would recommend contacting Dave.
To check your K2 for the presence of that mod, remove the bottom panel 
and look at D36 - if it is a clear PIN diode or a PIN diode mounted on 
and SMD carrier board, the mod is installed.  That mod is important for 
preventing keyclicks which are not noticeable for the QRP K2, but become 
obvious with the KPA100 (or other amplifier).

73,
Don W3FPR


On 10/24/2021 3:52 PM, jerry wrote:
> So:   Somehow I wound up with two K2s.  I bought the first one because 
> it was small - multiband - and QSK.  I have
> become enamored of transparent, conversational QSK - the kind where 
> your transmitted signal just sounds like all the other signals.  The 
> K2 alas is not that, although it is PIN diode switched.  I don't think 
> any commercial transceiver is.
>
>   Got K2 #2 to get the KPA100.  Moved the KPA100 to #1, because #1 has 
> all the good mods - the PLL mod, the volume control mod, the upgraded 
> crystals, etc.
>
>  The closest I have been to really good QSK is a QRP-labs QCX+ kit.  
> But it's only one band, and the receiver is probably not as good as a 
> K2 with a crystal filter - and K2 #1 even has the DSP audio filter.  
> AND it lacks AGC.  I was operating field day, a local came on and 
> nearly blew me out of my chair :).
>
>   So here's my idea for perfect QSK:  I use the two K2's as a 
> transmitter receiver pair.  One on transmit, the other on receive.  
> Connect them to the antenna with a custom PIN diode switch.  W6JL has 
> a lot of info on that in his QRZ page.
> Arrange something like 130dB attenuation.... or whatever 100W ( or 
> 500w if I use a linear ) down to a microvolt or two.
>
>  HOWEVER... I really don't want to be synchronizing VFOs all the 
> time.  So I find some sort of open source transceiver
> control program.  And modify it so it tunes TWO radios at the same time.
>
>   How good is QSK on the K4?  Smooth/transparent?  Or 
> clicky-choppy-AGC-pumpy?
>