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KNE Mini-QRP 40 meter

The Mini-QRP from Klaus Nathan Electronics is a new design being very similar to the design of the well known QRP-99.

Here you see a lovely picture of the rig ready on the desk. Down to the left you have a switch that is not used. This can be used for additional circuits that you might manage to cram into the box. I will probably build up a RF-clipper into the unit. The boxsize is 14 x 14 x 6 D, W, H (cm).

As you can see from the above block diagram there are a number of circuits that are used both in the TX and RX chain. The diagram is shown in relaystatus RX. If you walk trough the circuit from top left you see the following parts. The HF-amp consists of a Dual-gate FET and is only used for TX. Following you have 2 bandpassfilters for the 40 meter band. For the 40-meterband you do not need adjusting of the filter. The HF-amp is used for both RX and TX followed by an additional bandpass-filter. The NE612 is used for the first mixer circuit for RX followed by the 5 pole ladder X-tal-filter. In TX it is the SSB modulator. The 2 stage IF -amp consists of 2 BF961 dualgate FET:s. The second NE612 does the demodulation in RX and upmixer for TX. In the mid row you se the microphone amplifier stages.


Tilman D. Thulesius - [email protected]

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Further on you se the VFO/BFO switch putting the right BFO and VFO signals to the mixers depending on RX/TX. Out to the left you see the NF-amplifierstages with AGC-amp to control both of the AGC-amps. Down left you finally see the TX-amp-circuits.

The design is very straightforward "no trills". From the schematics above you see a cutout of the front-end with L1,2 C2,3,4 being the bandpassfilter followed by T1 being the HF-amp. IS1 and 2 being them two mixers acting as first mixer and demodulator. T2,3 being two BF961 dual-gate FET:s AGC-controlled VD6. The RX/TX-switching is done using relays giving a lowloss switchover.

The PA is pretty straight forward using 2SC1969 as T3,4. The output power is around 10 Watts for SSB/CW through the lowpass filter L1,2, C13 ­ 16. You can find further QRP-information having a look at my Internet homepage at URL: The kit can be obtained direct from Klaus Nathan in Germany. Call him on +49 3679 725767 (He prefers to speak German).


Tilman D. Thulesius - [email protected]

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I owe my OM Friend Tuomo "Pekka" Tupala SM0XCZ a big thank you for putting the unit together. He is a real pro with the soldering iron. And although he does not understand German he got the thing together without any major glitches. Here he sits in my shack working on the alignment of the QRP-mini. In the background you can see some of my vintage equipment.

Here you see the typical state of things from my hamshack-desk. The soldering is iron nearly always switched on. On the shelf you see additional QRP and homebrew equipment. From left RTX109 (all band, SSB/CW) power meters and a lovely YAESU FT817 that I remote control from my PC.


Tilman D. Thulesius - [email protected]

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