DB4020 Prepper material ?

Started by on6uu, July 11, 2020, 06:53:46 am

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on6uu

Hi, 
In May I got the EA3GCY newsletter in which the announcement was made of the availability of a new kit for 40 and 20mtrs,  the DB4020.
EA3GCY is Javier Solans who already had the EGV and ILER kits,  in 2017 he also made the MFT20 and MFT40 available,  both DSB transceivers, the 2 radio's kits have good performance and low current usage.
The main kit consist of the SSB part with all components but also with connectors and switches,  potmeters and encoder.  The kit also holds an electret microphone element to make your own microphone.  All components are well packed and the manual is well written with clear indications and a 252 square page to find back where everything needs to be soldered on the print.
The radio covers 7.0-7.2MHz on 40mtr and 14.0-14.35MHz on 20mtrs,  it has different tuning steps,  RIT function without freq limit,  LSB on 40,  USB on 20.
The promised 8W on 40mtr and 4W on 20mtr almost come true,  my DB4020 givees 7W on 40 and 3.5W on 20.  Carrier suppression is better then -40dB.

The receiver is of the superheterodyne type with balanced mixers,  sensitivity some 0.2µV.  The receiver has a 4pole crystal ladder filter,  2.4KHz nominal and has a superb working AGC.

Options are available to make this radio a multimode radio by means of a CW interface and CW 500Hz narrow filter.
The radio can be yours for 150€ (SSB) or 180€ for the multimode version (SSB and CW).
The main board is 180 x 140mm,  components are through hole.  The oled screen shows you frequency,  tuningstep, mode,  signalmeter,  RIT in use of not and a voltmeter i user mode.
The oled encoder makes it possible to altr all settings of RX and TX,  one can change IF offset,  IF frequency,  calibrate the Xtals,  calibrate the voltmeter and reset the complete transceiver.
Software is on an Arduino Nano.

what do I think of this kit ?
The kit came together in some 20 hours and in 2 stages.  I had the SSB part already before the CW part even was available thus the 2 stages.
As I already mentioned,  all through hole components,  all components spread over the board i a good manner,  I mean all components are not too cloose to each other which makes it easier to work.  I had more work with the militairy box I'm using then with soldering the kit .... ..  The box has 5mm walls and should withstand severe shocks and a drop to the dround.

SSB mode:
Some 3.5W on 20mtr,  some 7W on 40mtr,  the supplied electret does a good job,  I get good modulation reports back from everyone.  A superb working AGC is in the radio,  all stations sound very good,  even the very very strong ones.

CW mode:
The CW part of the kit consist of 3 boards,  one for the CW filter,  a CW interface holding also a keyer KB-2 with 4 memories,  beacon mode and much more.  The third board is a connection board for you paddle or straight key, it holds also a switch to switch from SSB to CW and visa versa and a push button which is the command key from where you control the KB-2 keyer.
The keyer can do 1-50WPM,  for most humans more then quick enough.
Also the CW part of the kit is well packed.

For the moùent there is no box to put the kit in,  one will be coming in the future,  Javier is working on a box.

Is this a prepper transceiver for HF ?  Well I think it can be one,  it has 2 bands where most are qrv on,  it doesn't use too much energy,  something like 0.4A in RX,  some 1-2A in TX depending on the output power you set it for.  So with these bands it should be possible to contact closeby stations as well as do DX in SSB and CW.

This is a transceiver almost everyone can make,  not too expensive and a no-nonsense radio.  It is rather small and can fit in most backpacks to do sota,  wff, activations or listen to broadcast ( 5MHz - 20MHz),  keep in mind that this radio is optimized for 20 and 40mtr.

I enjoyed making this transceiver,  I hope many will be made by QRP'ers,  preppers etc.

link to the site:
https://www.qrphamradiokits.com/

Link to my youtube channel:
https://www.youtube.com/watch?v=hGDwLdkr3HU&t=8s

73
ON6UU
Frank