CRKITS KN-Q7A Manuel

KN-Q7A

Single Band SSB Transceiver

Kit Manual

Rev. D

CRKITS.COM

Mar 2, 2014

Written by Adam Rong, BD6CR/4

Email:

http://www.crkits.com

Thanks to the following people for their editing and help.

Shi Ke, BA6BF

Jon Iza, EA2SN

Junichi Nakajima, JL1KRA

Mark McNabb, N7EKU

Qin Ling, BD4AHS

Ed Durrant, VK2ARE

Revision History

Oct 23, 2011: Rev. A, first formal release.

Nov 1, 2011: Rev. A1, modified a typo in step 5. Thanks JG1EAD for pointing out.

Nov 26, 2011: Rev. A2, removed an extra 104 capacitor near microphone input in schematics, and

corrected the injected audio amplitude from 5 mV to 1.5 V peak-peak in TX alignment section.

Also, changed microphone modulator to DSB modulator in step 3.

Apr 30, 2012: Rev. B, modified the manual to be compatible with both V2.1 and V2.1a PCB, and

fixed the description of SET BIAS for final power transistor IRF640.

Sep 12, 2012: Rev. C, modified the manual to be compatible with both 40m and 20m versions.

Oct 16, 2012: Rev. C1, modified based on the feedback from VK2ARE.

Mar 2, 2014: Rev. D, rewritten for PCB V2.2 and 20m version

THANK YOU!

Thank you for purchasing your KN-Q7ASingle Band SSB Transceiver Kit. The kit was designed

by BA6BF, and is now supplied by CRKITS.COM and its worldwide distributors. The KN-Q7A kit

is an ideal candidate for field operation, back pack and emergency use.

In this revision of manual, we have rewritten for PCB V2.2 and 20m version. 40m version will be

also covered, but if you want to read the manual for PCB V2.1a or earlier, please download from

http://crkits.com/knq7amanual_old.pdf

Specifications

Dimension: 153 mm x 97 mm x 40 mm, not including protruding features

Weight: 500 grams or 1.1 lbs

Power Supply: 12~13.8 V, 3 A

Current consumption: about 40 mA in RX and about 2 A in TX @ 13.8 V

RF output: about 10 W PEP @ 13.8 V (5 W PEP for the 20m version)

Spur suppression: better than -43 dBc

Sensitivity: better than 0.5 μV at 10 dB SNR

IF filter: 6 pole crystal ladder filter + 1 pole post IF amplifier crystal filter

IF bandwidth: about 2.0 kHz

IF frequency: 8.467 MHz, 8.192 MHz, or 4.194 MHz, depending on the selected tuning range

Frequency tuning range: about 20 kHz in VXO type. Options: 7.050~7.070 MHz, 7.080~7.100

MHz, 7.110~7.130 MHz, 7.145~7.165 MHz, 7.200~7.220 MHz, 7.280~7.300 MHz or

14.200~14.230 MHz

Connectors:

Speaker output: 3.5 mm connector, mono output

Microphone input: 8-pin, can be configured to be compatible with electret microphones or

speaker microphones

Antenna connector: BNC type

Controls:

IF Gain Control: act as volume control

Tune Control

Disclaimer

We offer the kit as is and do not guarantee the assembled kit by yourself can meet your local

regulatory requirements, including safety, RF, environmental or others. As some parts used in the kit

are obsolete, we cannot guarantee that all the components in the kit are brand new, but we bear the

responsibility of providing them as good as possible.

Tools Preparation

The tools needed for the kit building are solder iron, solder sucker, clipper, tweezers, pliers, screw

drivers including Philips and slotted, and a multimeter of digital or analog type. Besides, you will

need an electric drill and a 3 mm drill bit, a 50 Ω, 20 W or higher power dummy load, an HF band

SWR/Power meter, a 13.8 V/ 3 A power supply, a personal computer running Windows, an amateur

radio transceiver with a general coverage receiver and calibrated frequency display, and other

ancillary instruments. It will be nice if you have access to a frequency counter, an audio signal

generator, a RF signal generator, an oscilloscope and a spectrum analyzer, but they are not

absolutely required.

Parts Inventory

Open the package and read the one-page quick guide thoroughly. Also, some volunteers have

translated some manuals for you. To download your local language documents, you can search the

CHINA_QRP group file section on Yahoo or go to the document archive section of

http://crkits.com. There you will find a list of all documents (Thanks EA2SN for Spanish

translations and JL1KRA for Japanese translations).

You need to download the complete part list and do the parts inventory carefully.

40 m version: http://crkits.com/knq7apartlist.pdf

20 m version: http://crkits.com/knq7a20mpartlist.pdf

We have put resistors, trimmers, potentiometers and 104 capacitors into one plastic bag so it will

make your work much easier. You may find some extra parts, and it is fine to keep them as backup.

It is okay to discard the original metal front panel, rear panel and the original 8x panel screws now,

because they have replacements in the kit. If you find problems or missing parts, please contact

your seller directly.

We offer several frequency ranges to meet different requirements (this list is subject to change

without notice):

7.050~7.070, LO 15.540 1 pcs (strong pulling capability), IF 8.467, for Asia, Canada,

Australia

7.080~7.100, LO 15.570 1 pcs (strong pulling capability), IF 8.467, for Europe,Asia,

Australia, covering the 7.090 calling frequency

7.110~7.130, LO 15.600 1 pcs (strong pulling capability), IF 8.467, for Europe, Asia

7.145~7.165, LO 15.360 2 pcs, IF 8.192, for North America, Asia and Europe

7.200~7.220, LO 15.418 1 pcs (strong pulling capability), IF 8.192, for North America

(General Class)

7.280~7.300, LO 15.500 1 pcs, IF 8.192, for North America (General Class), covering the

7.285 calling frequency

14.200~14.230, LO 18.432 1pcs (strong pulling capability), IF 4.194, for 20m worldwide

For the VXO crystal with strong pulling capability, the VXO range can be pulled much wider, up to

200 kHz by adjusting the VXO coil, but frequency stability gets worse and we don't officially claim

support.

Board Assembly

We will do it step by step, finishing one part of assembly at a time, and testing it to ensure final

success. We will provide partial schematic in each step to help you understand the theory of

operation, and make sure you install all the parts required to do the final testing of the block.

However, the partial schematic might not contain all the parts you should install in each step, so

don't get confused when you are told to install a part not shown on the schematic. Note that PCB

version is subject to change without prior notice and it may look slightly different from yours.

In the photo below, PCB version is printed on the PCB between two potentiometers. 1~8 means

building steps and A~D means:

A –BFO crystal marked by Xa’. The red dotted crystal should be installed here if your kit has one.

B –Only this DIY7-7 coil should be reworked to remove built-in tubular capacitor before soldering.

C –Install the only one light green 104 monolithic capacitor here

D –Preset this trimmer fully counterclockwise before you apply power supply. When you adjust the

bias voltage for the final PA, turn it clockwise very very slowly, or the final PA is easily damaged.

Step 1: Power Supply Circuit

Let's start with the power supply circuit. Should you want to study the whole schematic prior to the

building to have better understanding, you may find a copy of the circuit at the end of this manual.

Please study the partial schematic before soldering.

[ ] Solder 1x DC IN socket, and trim the pins flush to avoid shorts with chassis foot screws

[ ] Solder 1x speaker connector near the DC IN power connector; make sure you install it in

place

[ ] Bend the pins of 1x 1N5401 diodes as shown, and solder. For other diodes, always bend the

pins like this. If you kit comes with 1N5820~1N5822, it is an upgrade for lower dropout voltage.

[ ] Solder 1x 1000 μF capacitors; check polarity

[ ] Solder 1x 0.1 μF (104) monolithic capacitor near 7808. Remember that all capacitors

without marking are 104 ones.

[ ] Solder 1x 7808 as shown for test purposes now. If your kit comes with LM2940-8.0, it is an

upgrade for lower dropout voltage.

[ ] Plug in a 12~13.8 V power supply to the DC IN connector (center positive) and measure the

voltage on pin 3 of 7808 near to the 104 capacitor to see if it is within +/-5 % of 8 V; if not, check

power supply polarity and your soldering

[ ] Disconnect the power supply and proceed to the next step.

Step 2: Audio Amplifier

The core component of the audio amplifier is a TDA2822M. It is a dual channel amplifier but we

only use one channel here. Please study the schematic before soldering.

[ ] Place 1x 8 pin IC socket, paying close attention to the notch, and solder, then insert a

TDA2822M with correct orientation as shown on the photo

[ ] Solder 1x 1000 μF capacitors; check polarity

[ ] Solder 2x 100 μF electrolytic capacitor; check polarity

[ ] Solder 1x 10 μF electrolytic capacitor; check polarity

[ ] Solder 1x 8050 transistor; check PCB outline

[ ] Solder the remaining capacitors and resistors; when finished, it will look like the photo

below

[ ] Plug in a 12~13.8 V power supply and connect an external speaker of 8 Ω or higher

impedance to the speaker connector. Touch pin 5 of the nearby NE602A using tweezers to inject

some noise, and note if the audio amplifier works. If not, please check your soldering, and check the

pin 2 of the TDA2822M for the presence of 8V. If all is okay, disconnect the power supply and the

external speaker to proceed to the next step.

WARNING: It is not a good choice to plug in a headphone to the speaker connector, as the radio

does not have an AGC circuit and an abrupt strong signal or noise may cause hearing impairment.

Step 3: Detector/ Double Sided Band Modulator

The core component is a double-balanced mixer and oscillator NE602A. It acts as the detector in

the RX path and also as a DSB modulator in TX. Please study the schematic before soldering. Xa’is

a marking for BFO crystal. It is red dotted on the top for 20m version, but same as other IF crystals

for 40m version.

[ ] Place 1x 8 pin IC socket, paying close attention to the notch, and solder, then insert a

NE602A with correct orientation as shown on the photo

[ ] Pick 1x BFO crystal and solder. You don't have to place an insulator under the crystal or

ground the crystal case

[ ] Solder 1x 15 pF capacitor near VC. Remember the marking 22 uH/ 15 pF means for 40m

version install 22 uH inductor or for 20m version install 15 pF capacitor

[ ] Solder 1x trimmer capacitor VC as shown on the photo

[ ] Solder 1x SIP5 socket as on-board microphone connector as shown on the photo

[ ] Solder 1x relay. This relay is controlled by the PTT and switches 8 V RX/ TX power

[ ] Solder 1x 104 monolithic capacitor near 1000 μF capacitor. Remember that all capacitors

without marking are 104

[ ] Solder 1x 1N4148 near the relay. Remember that all diodes without marking are 1N4148 and

bend the pin near the bar marking on the body

[ ] Solder the remaining inductors, resistors, diodes and capacitors. When finished, it will look

like the photo below.

[ ] Plug in a 12~13.8 V power supply. Short the PTT pin to GND to see if the relay works. Use

a nearby general coverage SSB/CW receiver to hear the leakage of the BFO within +/-2 kHz range

of the marked frequency. Connect an external speaker to the speaker connector and touch pin 1 of

the NE602A using tweezers to note if the noise coming out of the speaker increases. Check your

soldering and the presence of 8 V on pin 8 of NE602A if it is not normal. If all is okay, disconnect

the power supply and the external speaker to proceed to the next step.

Step 4: RX IF Amplifier

The core component is an MC1350. There is no AGC circuit designed, and the IF gain is controlled

by a potentiometer (IF GAIN) and also used as volume control.A crystal filter is added after the

output network of the MC1350. Please study the schematic before soldering. Xa is a marking for IF

crystals. Don’t install means the capacitor is not required for 20m version. Always check PCB

marking for the difference between 20m and 40m versions.

[ ] Place 1x 8 pin IC socket, paying close attention to the notch, and solder, then insert a

MC1350 with correct orientation as shown on the photo

[ ] Pick 1x IF crystal and solder. You don't have to place an insulator under the crystal or

ground the crystal case

[ ] Pick the potentiometer marked B10K and solder it as IF GAIN control, making sure that the

shaft is vertical to the PCB side

[ ] Solder the remaining inductors, resistors and capacitors. When finished, it will look like the

photo below. Note that from PCB V2.1a, a resistor of 1.5k is added between pin 4 and pin 6 of

MC1350 to improve receiver audio fidelity.

[ ] Plug in a 12~13.8 V power supply and connect an external speaker to the speaker connector.

Turn the potentiometer to fully clockwise, touch pin 6 of MC1350 using tweezers and note if the

noise coming out of the speaker increases. Turn the potentiometer counter clockwise to note if the

noise decreases. If it is not normal, please check your soldering, and check the pin 1, 2 and 8 of the

MC1350 for the presence of 8 V. If all is okay, turn the potentiometer fully clockwise again, and

disconnect the power supply and the external speaker to proceed to the next step.

Step 5: IF Crystal Filter

This part includes 6x IF crystals, 7x capacitors and 2x relays. Please study the schematic before

soldering. Xa is a marking for IF crystals. Always check PCB marking for the difference between

20m and 40m versions.

[ ] Pick 6x IF crystals and solder. You don't need to place insulators under the crystals or ground

the crystal cases

[ ] Solder 7x 27 pF capacitors (for the 40m version, they are 7x 47 pF)

[ ] Solder 2x relays. When finished, it will look like the photo below

[ ] Plug in a 12~13.8 V power supply and connect an external speaker to the speaker connector.

Touch pin 5 of the uninstalled NE602A using tweezers to note a little noise from the speaker. If it is

not normal, please check your soldering. If it is okay, disconnect the power supply and the external

speaker to proceed to the next step.

Step 6: Mixer and VXO Local Oscillator

The core component is another double-balanced mixer and oscillator NE602A. It acts as the RX/TX

mixer and the local oscillator (LO). Please study the schematic before soldering. Xb is a marking

for VXO crystal(s). Always check PCB marking for the difference between 20m and 40m versions.

[ ] Place 1x 8 pin IC socket, paying close attention to the notch, and solder, then insert a

NE602A with correct orientation as shown on the photo

[ ] Pick 1x IFT DIY7-7, and use a small slotted screw driver to press and break the built-in

tubular capacitor, and remove all the loose fragments. The photo shows the original IFT on the left,

and the reworked IFT on the right. Place it on the PCB and solder

[ ] Solder the VXO crystal(s). You don't need to place insulator under the crystal or ground the

crystal case. You may need to solder 1x or 2x crystals, depending on the frequency range you have

selected for your kit. If you just need to solder 1x crystal, either slot will be okay

[ ] Solder the diode BB910. Place BB910's marking side to face the TUNE potentiometer and

away from the VXO crystal(s), and solder

[ ] Pick the potentiometer markedA10K and solder it as the TUNE control, making sure the

shaft is parallel to the PCB and vertical to the PCB side. Turning the potentiometer clockwise will

increase the frequency of the LO

[ ] Solder 2x 27 pF capacitors (for the 40 meter version, they are 2x 47 pF)

[ ] Solder the remaining parts. When finished, it will look like the photo below. Note that from

PCB V2.1a, a 10k resistor is added between the center pin of potentiometer and ground to help

improve the tuning linearity of high end frequency range.

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