Re: K3 for CW


Hi Martin,

On the issue of receiver latency compromising QSK operation, I don't think the T/R switching necessarily introduces any significant latency. (My RJ-1 vacuum relay switches in 1.4 ms!) Receiver recovery can be made fast enough by proper AGC design. However, a DSP unavoidably introduces delay, in addition to the inherent delay of any narrow filter. I think the DSP delay can be reduced by using a faster processor and/or sampling rate, but I'm not sure. Perhaps someone can fill us in.

Scott K9MA

On 10/4/2020 3:20 AM, Martin Kratoska wrote:
Hi Scott,

your observation is correct, at least in particular. I don't have now any ricebox to confirm this. Anyway some numbers can be measured with Keying Analyzer by Nick, WA5BDU (attached), of course some not. I agree, a separate RX and TX with a 6AH6 antenna switch is unbeatable stellar performer although it introduces some level of attenuation into RX path. The "processorless" were much better (speaking about QSK) than the modern DSP/DDS gear. AFAIK the RX "recovery time" is mostly introduced by firmware built-in delays. Manufacturers won't allow any artifacts on the receiver audio during the switching time, unfortunately no firmware allows to adjust it. Anyway, the K3 with new synthesizers KSYN3A is still the best QSK radio on the market - if you have other info, tell me, please.

My idea is to extend the WA5BDU gem to measure RX audio. It seems that it will need another channel detecting the presence of an audio signal. I plan to get in touch with WA5BDU to do this.

Martin, OK1RR

Dne 04. 10. 20 v 3:11 K9MA napsal(a):
Hello Martin,

I've been using QSK for many, many years, going back to the days of vacuum tube radios. The one thing that disappoints me about the K3 and other modern DSP radios is that the receiver latency is so long that even at 30 wpm or so, you can't hear between dots and dashes, only between letters or words. Even my old FT-1000D (no DSP) is much better. Have you noticed that? I really miss the transparency fast QSK gave us. I guess that's the price we must pay for the benefits of QSK.

Scott K9MA

On 10/3/2020 7:31 PM, Martin Kratoska wrote:
I am 99.99% on CW. I have 250-400-1k-1k8-2k8 8-pole filter set in both main and sub RX (10 filters total!). My K3 #7554 with new synthesizers is the best radio I used in my 50+ years of ham radio activity. Good QSK is a mandatory for me, I do often also QRQ up to 60 wpm.

Your choice of K3 is excellent.

Martin, OK1RR

P.S. I strongly hate clicking antenna relays, the fast & silent PIN diode switching (K3 and KPA500) is mandatory for any rig in the future.

Dne 02. 10. 20 v 17:39 SGS 126 napsal(a):
I have recently gotten back into CW and I want to get a K3 purely for CW. I have seen plenty of K3/100/AT for under $2000. My code speed is between 13-18 wpm, but I am trying to get proficient so that is why I am looking at the K3 to use for code and build up my proficiency. I presently have an Icom 7300 which I know would work fine but I like that the Elecraft uses PIN diodes for switching. Any recommendations on must-have filters?

Thanks, Ben KJ4CC

Scott  K9MA


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