My new HF home made QRP transceiver – first sight

Here it is – our home brew transceiver is alive.

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Die plastic mold is not ready yet so we ordered CNC machined aluminum panel.

All the plastic knobs are 3D printed (waiting for the plastic mold)

FSTN display is super nice -bright and sharp in all viewing angles. We approved the 5 samples sent by the manufacturer and now wating for the first production batch.

Stay connected for future news!

73, LZ2JR/AC9IJ

Weighted knobs MAIN and SUB for Elecraft K3

Elecraft K3 is a super performer HF radio and has been sitting on my bench for many years but the knobs need to be improved. To add some more precise movement and better aesthetic effect we made these heavy bronze knobs MAIN and SUB. When the friction between the knob and  the textile ring is proper adjusted tuning is fast & easy and you will like your equipment even more.

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BITX multiband metal enclosure

I purchased ready made metal enclosure – EM series

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Here is how it must look after making the front panel:

front panel silk screen

front panel silk screen

 

 

 

VFO /variable frequency oscillator/ by sdr-kits.net

Here I will share my experience with PA0KLT VFO kit.

VFO kit based on Silicon Labs digital synthesizer chip Si-570 arrived too fast from UK with ordinary post service /a week or so/. I purchased new version with implemented additional buttons for RIT and FAST functions .. also with ability to exchange the main mechanical tuning knob with optical encoder. Building the unit is not difficult at all and passed straight forward… even placing Si570 chip is not a pain.

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The unit comes to alive from first attempt. I’ve used it for two months now with my multiband BITX – home made transceiver.

I like that it has rock solid frequency stability and accuracy. It has well organized config and memory menu for calibration, writing in memories, assigning IF /intermediate frequency/. Mode selection – CW, USB, LSB and AM. Two VFO’s and memories

What I dislike is:

1. It cannot memorize the last position of the VFO when shutting down… After switching power supply on again it always runs from VFO A?!

2. Band decoding is not correct according the manual. The table in the manual is not correct. Then I decided to contact PA0KLT directly so he did send me correct band decoding tableHere I suggest another table which is more suitable for BITX multiband transceiver.

3. IF shifts for CW/USB/LSB cannot be adjusted separately. For LSB/USB it is assigned to be ±1.5kHz and for CW ±0.75kHz which is not flexible and limits the use of different crystal filters /wide and narrow/ .. also different positions of the carrier crystals. In those cases the frequency shown on LCD would be incorrect!

4. The microcontroller used in the VFO does not support other type encoders with more PPR /more than 25ppr/ … so the tuning speed is way too slow so use of X5 rate or ‘< ‘ ,  ‘>’ buttons are mandatory.

My BITX Multiband transceiver

Recently I decided to join this interesting project and purchased semi KIT from Sunil – VU3SUA. Kit consists of all three boards – exciter, LPF and BPF and parts for the exciter board. Multiband concept of the BITX transceiver has been developed by Andy – G6LBQ. Further I purchased toko inductors from Spectrum Communications – UK and PA0KLT Si-570 VFO kit from sdr-kits.net.

Here is how it looked in the begining:

Some hard to find parts as double balanced mixerADE-1 I supplied from ebay.co.uk and other internet sites.

Si-570 is excellent chip and gives pretty much signal at the output… so it must be conditioned to suit 7dbm level requirement for diode DBM mixer ADE-1. Also suitable low pass filter should be added in order to achieve good sinusoidal signal. As seen on the photos I used an old KVG 2.4kHz crystal filter XF-9B with carrier crystals.

As seen on the photos  I placed some tin shields between the stages of the exciter board and some additional grounding on the bottom side. This and placing low pass filter on BFO output completely cured so called BIRDIES problem. Also this improved carrier attenuation on transmit.

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