ZL2PD Builds the KN-Q7 40m QRP SSB Transceiver
This handy 10W PEP SSB kitset transceiver
features a single-board design and fits in a compact aluminium case.
KN-Q7 is a low power (QRP) transceiver kit designed in China by amateur
radio operator BA6BF. New Zealand was one of the first places to
receive this kit. It was supplied locally by FutureTech.
Having built the kit, I felt there were a number of areas in which the
kit instructions could be improved. I noted down all the areas where I
had a few problems, and documented it all.
In addition, I think there are lots of possibilities to enhance the
design. Things like an antenna tuner, an SWR meter, a power supply,
additional bands, wider range VFO. The list goes on!
For the moment at least, this page includes:
1. My set of instructions on how to build this kitset, including hints
on some tricky areas
2. A corrected schematic
3. A picture of the board just before I mounting it in the chassis, and
4. Some specifications on some of key components used in the KN-Q7
Disclaimer: I have no
association whatsoever with either FutureTech or BA6BF
Why New Instructions?
Further down on this page, in the section titled 'Downloads', you can
click on and download a new set of instructions on how to build the
KN-Q7 transceiver kitset.
Why did I create a new set of instructions? Doesn't the kit contain
Well, yes. The kitset does include some instructions. It's just there
are quite a few little details that are not included. There were a few
errors in a couple of places, and the schematic was a little difficult
to follow... So, while the transceiver kit is quite
straightforward to build for experienced builders, these instructions
are intended to make the task easier for the rest of us. And besides,
why repeat my mistakes?
These new instructions also follows my preferred method of construction
-- One stage at a time.
Building the transceiver section by section, and testing each section
as soon as you've completed it, allows any faults to be located more
quickly. A fault is probably somewhere in that last set of parts you
just added. Now, this is in stark contrast to the instructions provided
with the kit. It suggest the opposite approach i.e. Build everything
all in one go, and then test it. Well, fine. Personally, I find that is
not the best approach. A fault can be very tough to find when you’ve
got an entire board of parts and connections to check!
Anyway, I followed my step-by-step approach, and it worked. It also
allowed me to break up the construction into a bunch of easy stages,
with breaks well-timed for coffee. But, hey, it's your kit, right? You
My instructions allow you to build the kit in the following stages:
1. Parts Inspection and Sorting
2. Surface Mount Devices - 3 chips to be soldered onto the PCB first
3. 8VDC regulator and rear panel sockets (Speaker and DC input)
4. Receiver audio
5. Second Mixer and BFO - Doubles as the transmit microphone
amplifier and carrier oscillator
6. Transmit-Receive Power Supply Switching
7. Receiver IF Amplifier
8. IF Crystal Filter
9. First Mixer - Includes the Variable Crystal Oscillator (VCXO)
10. Receiver Bandpass Filter
11. Coil Winding
12. First Transmit Amplifier and Transmit Bandpass Filter
13. Second Transmit Amplifier
14. Third (Final) Transmit Amplifier and Low Pass Filter
15. Final Mechanical Assembly
The transceiver PCB shown here is
almost complete. The next step is to mount it onto the base of the
enclosure and solder in the antenna connector. The chassis acts as the
heatsink for the transceiver. The required mounting holes for the three
power devices must be drilled by the kit builder. Not too difficult!
Right click the photo for a closeup
Some Component Specifications
For those interested in the inner workings of the transceiver, or
perhaps wanting to make some modifications to improve performance, I
have attached some specifications for a few of the parts used in the
KN-Q7. Just click on the component.
MC1350 IF amplifier
TDA2822 audio amplifier
2SC3357 1st tx amplifier
2SC1162 2nd tx amplifier
IRF640B Final tx amplifier
Thanks to the various vendors and alldatasheet.com
for many of these PDFs!
to download the latest version of ZL2PD's kit building instructions
(PDF file : 600k)
Click here to download the
latest ZL2PD version of the SCHEMATIC
(PDF file : 66k)
I have built a number of accessories to go with my new KN-Q7
An antenna tuner -
so I can use a variety of antennas when I take this transceiver on my
simple SWR meter - I shall probably eventually build this into the
TuneAid - This is documented on another page on this site
12V/2A power supply - I made two versions, and these are documented
on another page on this site
If I get a bit more time, and as I finish these off, I’ll put the
details up on this site. Stay tuned!
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