Hey Adam,

When will a 80m/75m version of the CS-Series transceiver be released?

Thank you,

John

AA7US

---In CHINA_QRP@..., wrote :

• 80m/75m/40m/20m/17m/15m will be supported. 40m/20m is now available

 

Hi John and all

While replacing the final  FET I forgot to put the insulator under the nut holding it to the heat sink case so it was shorted s soon as power was applied and burn’t out the winding on T3.   I rewound it with 0.63mm wire on the original toroid and the wires fitted the centre hole without any problems.    I saw the info  about changing the toroid.    I wonder if it is becoming saturated when using digital modes.   I also learnt to put a 2 amp in the power supply lead , much easier to replace than the FET.    Also my local supplier did not have the original FET but a higher current rating and seems to work well. (IFR-540)  This was not my radio but will purchase one for myself.   Great project kit thanks Adam.

On 13 Aug 2017, at 9:08 am, landrjoh@... [CHINA_QRP] <CHINA_QRP@...> wrote:

Adam,

Is it acceptable to use a heavier gauge (larger diameter) wire when winding a larger toroid such as the FT50-43?

Thank you,

John

AA7US

---In CHINA_QRP@..., wrote :

This is why our recommendation is that you change the ferrite toroid from FT37-43 to FT50-43 or even bigger.

Bob Hudson

vk2aor@...

 

Hey gang,

In looking over the characteristics of the new weak signal FT8 digital mode, I noticed it has a sustained TX time of only 15 seconds (versus nearly 50 seconds for JT9 and JT65).  Presumably this is followed by a minimum 15 second RX period... probably a bit longer.

Wouldn't this new FT8 digital mode be a lot easier on the IRF510 final amplifier found in our KN-7QA and CS-series transceivers compared to JT9 and JT65?  It should cause a lot less heat buildup right?

The following excerpt is from the version 1.8.0 release candidate WJST-X software:

Brief Description of the FT8 Protocol
		-------------------------------------

WSJT-X Version 1.8.0 includes a new mode called FT8, developed by K9AN
and K1JT.  The mode name "FT8" stands for "Franke and Taylor, 8-FSK
modulation".  FT8 uses 15-second T/R sequences, provides 50% or
better decoding probability down to -20 dB on an AWGN channel, and 
maintains good performance on Doppler-spread fading channels.  An
auto-sequencing facility includes an option to respond automatically
to the first decoded reply to your CQ.  FT8 QSOs are 4 times faster
than those made with JT65 or JT9.  FT8 is an excellent mode for HF
DXing and for situations like multi-hop E_s on 6 meters, where deep
QSB may make fast and reliable completion of QSOs desirable.

Some important characteristics of FT8:

  - T/R sequence length: 15 s
  - Message length: 75 bits + 12-bit CRC
  - FEC code: LDPC(174,87)
  - Modulation: 8-FSK, tone spacing 6.25 Hz
  - Constant-envelope waveform
  - Occupied bandwidth: 50 Hz
  - Synchronization: 7x7 Costas arrays at start, middle, and end
  - Transmission duration: 79*1920/12000 = 12.64 s
  - Decoding threshold: -20 dB; several dB lower with AP decoding
  - Multi-decoder finds and decodes all FT8 signals in passband
  - Optional auto-sequencing and auto-reply to a CQ response
  - Operational behavior similar to JT9, JT65

We plan to implement signal subtraction, two-pass decoding, and use of
a priori (AP) information in the decoder.  These features are not yet
activated in v1.8.0.

We haven't yet finalized what the three extra bits in the message
payload will be used for.  Suggestions are welcome!

	-- Joe, K1JT, for the WSJT Development Team

 

Hi Adam,

Is the substitution of an FT50-43 toroid for T3 a recommended upgrade for any frequency band of KN-Q7A / CS-series transceiver if we want to try digital modes (long transmission times)?

Thank you,

John

AA7US

---In CHINA_QRP@..., wrote :

My first idea is that the final transformer T3 should be replaced by an FT50-43 toroid to avoid saturation.

My first idea is that the final transformer T3 should be replaced by an FT50-43 toroid to avoid saturation.