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SP2SWI Poland flag Poland

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SKCC Hello, my name is Mariusz. I was born in 1967. I have been licensed since 1990.

I'm a big fan of working QRP CW (with 5 Watts or less). Since July 2013 the power of my station is always QRP or QRPp.

The station is quite basic. I using homebrew simple wire and vertical antennas.

PZK Member of SKCC # 14331 (Straight Key Century Club). I'm still learning CW, so PSE QRS :).




  • KNB2 (Noise Blanker Option),
  • KAF2 (Audio Filter Option),
  • K160RX (160m Module with RX ANT Switch),
  • KAT2 (Automatic Antenna Tuner),
  • KIO2 (Aux I/O Module - RS232 Interface),
  • K60XV (60m Module with Transverter Adapter),
  • KBT2 (Internal Battery 2.9 AH).

My primary transceiver now. I built K2 in November 2014. It really is the perfect QRP radio. Crystal filter works perfectly! Audio filter (KAF2) also works great.

I made only minor modyfications: Improved low frequency audio (C25, C26 0.1uF --> 0.33uF on the Control Board and C12, C13 0.22uF --> 0.33uF on the KAF2 Audio Filter Board) and K6XX CW Indicator (CW zero beat detector).

Elecraft K2 with K6XX CW Indicator (CW zero beat detector) Elecraft K2 QRP Transceiver and Junker Straight Key

- Ten-Tec Century 22 - CW TRX (model 579 from 1984) with Crystal Calibrator (model 226). Power levels ranging from a few mW to 5 W out max (I reduced max output power from 20W to QRP 5W by the new ALC level setting). I love transceivers prior decades.

I love this transceiver! Very fast, smooth QSK/full break-in. Perfect 4 pole CW bandpass audio filter (Ten-Tec Century 22 has a direct conversion receivers). Filter is inside the AGC loop and filter action does also impact the AGC action. It works very well! I bought this transceiver in January 2013.

Adjustment and modification of Ten-Tec Century 22 (Model 579)

Ten-Tec Century 22 and German Junker straight key Ten-Tec Century 22 Ten-Tec Century 22 (Model 579) Ten-Tec Century 22. New ALC level setting. Max RF power is now 5W out (QRP).

- OHR 500 - 5 Band QRP CW TRX (kit from Oak Hills Research). I bought this transceiver in August 2013. I confirm reviews from eham.net. Lovely radio!

Oak Hills Research - OHR 500 5 Band QRP Transceiver OHR 500 OHR 500

- Elecraft KX1 - QRP CW TRX with KXAT1 internal antenna tuner (80,40,30,20m; ~3 W out),

- PIXIE 2 (80m) - homebrew QRPp CW TRX with sidetone and BCI filter (80m; ~300 mW out).

SP2SWI Pixie 2 QRP (QRPp) CW transceiver with sidetone and BCI filter - Schematic

- PIXIE 2 (40m) - kit from China. Full QSK QRPp CW Transceiver. TX frequency is fixed at 7.023,04 MHz. 600 Hz frequency shift (adjustable). PWR is 228 mW out @ 9V (360 mW @ 12V; 422 mW @ 13.8V). RX current: 12 mA, TX current: 102 mA @ 9V.

My mod: I added a simple RC lowpass filter at the input of audio amplifier LM386 (R = 10k, C = 22nF, cut-off frequency = 723 Hz). Now Pixie is much more selective. Ears are not overloaded now :).

Audio CW Lowpass Filter mod for Pixie 2 Transceiver


I use a German Junker DBGM Straight Key with the revised knob. Knob from old Russian Key (10RT Tank Radio).

Junker Straight Key Junker DBGM Key


- Homebrew GP for 20m band. Monoband vertical for 20 m band (full size λ/4 ground plane antenna with 7 radials λ/4 sloped down about 35-40°). No traps, no losses :). Aluminum pipe (from λ/2 CB antenna) ~5.10m long and stranded copper wire 4mm2 (~11 - 12 AWG) 5.15m long. Highly efficient antenna.

SP2SWI Homebrew GP Antenna 20m Band - 1 SP2SWI Homebrew GP Antenna 20m Band - 2 SP2SWI Homebrew GP Antenna 20m Band - 3 SP2SWI Homebrew GP Antenna 20m Band - 4 SP2SWI Homebrew 20m Band Ground Plane Antenna - SWR and impedance Z (Ohm)

- Homebrew Fan Dipole for 40m and 30m band. Stranded copper wire 6mm2 (~10 AWG). 2 x ~10.1m and 2 x ~7.1m. Balun 1:1 (Diamond BU-50) and additionally current balun (ferrite beads on coax at antenna feed point). Antenna sloping at an angle of about 20-25 degrees from horizontal (10m up side and 2m down side).

Previously, I had the T2FD antenna (Tilted Terminated Folded Dipole), but even though T2FD is super antenna for noise urban jungle (better signal-to-noise ratio than a vertical or dipole) was too not effective to work QRP .

QSL Info

I prefer electronic QSL via LoTW, eQSL.cc or QRZ.com Log.

LoTW LogBook  SP2SWI eQSL Authenticity Guaranteed  SP2SWI eQSL

Never add /QRP to my callsign.

"SP2SWI" --> Yes | "SP2SWI/QRP" --> No

It's just a source of potential confusion (on LoTW, eQSL and elsewhere). My power is certainly QRP or QRPp (since July 1, 2013).

My lovely dog :)

Mariusz Stramowski (SP2SWI) and dog Jim

Adjustment and modification of Ten-Tec Century 22 (Model 579)

Sorry for my English. :)

- Adjusting the "TX OFFSET"

I had to adjust the "TX OFFSET" trimmer potentiometer on the "RX / Control Assembly" because it was badly adjusted.

1. Unscrew the cover (lower part), connect the antenna or dummy load, turn the transceiver on and wait 30 minutes.
2. Set the "DRIVE" (on the front) to a minimum.
3. Set the "OFFSET" (on the front) exactly to "0" (center detent).
4. Connect the frequency meter (high input impedance, low capacitance) to the PTO oscillator output (where the coaxial wires are soldered).

Ten-Tec Century 22: PTO Oscillator Output and TX Offset Trimmer Potentiometer
5. Read frequency (it will be a value in the range of 6.0 to 6.5 MHz), with the precision of at least 10 Hz !!

Ten-Tec Century 22: Frequency of PTO Oscillator
6. Press the "LOCK" (on the front).
7. Adjust the trimmer potentiometer "TX OFFSET" (on RX/Control Assembly), so that the frequency was the same as in step 5.
8. Turn off the "LOCK".
9. Disconnect the frequency counter. Screw the cover.
10. Done.

- Greasing the Ten-Tec Century 22 PTO

I do not know when the PTO was greased, so I decided to dismantle, clean, greased and reassemble again.

To remove the knobs are needed Allen keys (hex keys): .050'' and 1/16''.

Ten-Tec Century 22: To remove the knobs are needed Allen keys

Very helpful in removing the PTO is a guide written by Dave (N5XL, VE5AEA) "PTO Rebuild and Dial Restring for the Ten Tec 579 (Century 22) Transceiver": ttc22pto.pdf. Thanks Dave!

The next steps:

Ten-Tec Century 22: Dial Cord - 1 Ten-Tec Century 22: Dial Cord - 2 Ten-Tec Century 22: Dial Cord - 3 Ten-Tec Century 22: PTO Oscillator - 1 Ten-Tec Century 22: PTO Oscillator - 2 Ten-Tec Century 22: PTO Oscillator - 3

All elements of the PTO should be cleaned with a toothbrush, cotton cloth and isopropyl alcohol.

Ten-Tec Century 22: PTO and Isopropyl Alcohol

I used all-purpose lithium grease "MULTIFAK EP 2" from Texaco, because that I found in my garage :). "MULTIFAK EP is a multipurpose grease family made from refined mineral oils and a lithium soap. MULTIFAK EP greases offer great shear resistance, retain their consistency under adverse service conditions and protect bearings and other metal surfaces from corrosion when exposed to wet conditions. MULTIFAK EP greases are non-corrosive to non-ferrous bearing metals as well as steel. MULTIFAK EP contain extreme pressure additives as well as rust and oxidation inhibitors. MULTIFAK EP are recommended for both automotive and industrial purposes as multipurpose lubricating agents for friction pairs operating." I think it will work well in the PTO.

Multifak EP 2 All Purpose Lithium Grease

PTO lubricated. Now PTO works very smoothly and precisely. I hope that it will be a long time :).

Ten-Tec Century 22: PTO lubricated

It's time to check whether the PTO oscillates at least from 6.0 MHz to 6.5 MHz.

Ten-Tec Century 22: Output frequency range of PTO - 1 Ten-Tec Century 22: Output frequency range of PTO - 2

Done. Everything works fine.

- Modification center frequency of audio filter

I rebuild bandpass audio filter (audio filter between the detector and audio amplifier). Ten-Tec Century 22 has a direct conversion receivers and the audio filter is very important to ensure good selectivity. For me, the center frequency was too low.


Ten-Tec Century 22: CW audio filter schematic

I made the measurement. The center frequency was 510 Hz (bandwidth was about 250 Hz):

Ten-Tec Century 22: center frequency of audio filter: 510 Hz
I decided to change the center frequency to 600 Hz, because this is my listening CW frequency. I replaced capacitors C41 C42, C43, C44, C45, C46, C47, C48 and replaced resistors to resistors with tolerance of 1%. You can use this calculator to choice capacitors and resistors. Example:

Input data for calculations:

  • Center Frequency = 600 Hz;
  • Gain = 1;
  • Q = 2.4 (for bandwidth 250 Hz @ -3 dB, for a single operational amplifier);
  • C41-C48 = 3 nF.

Result of the calculation:

  • R60, R63, R66, R69 = 212.2 kOhm;
  • R62, R65, R68, R71 = 424.4 kOhm;
  • R61, R64, R67, R70 = 20.17 kOhm.

Standard E96 1% tolerance resistors: 210k/1%, 422k/1%, 20k/1%.

The next steps:

Ten-Tec Century 22: RX/Control Assembly - 1 Ten-Tec Century 22: RX/Control Assembly - 2 Ten-Tec Century 22: RX/Control Assembly - 3 Desoldering resistors and capacitors Resistors and capacitors Ten-Tec Century 22: RX/Control Assembly - 4 Ten-Tec Century 22: RX/Control Assembly - 5 Ten-Tec Century 22: RX Control Assembly - 6

Filter test:

Ten-Tec Century 22: center frequency of audio filter: 600 Hz

Done. The center frequency is 600 Hz (bandwidth is about 250 Hz). The filter works well.

- Links


7570446 Last modified: 2016-09-15 08:06:21, 64921 bytes

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QRZ Logbook Summary for - SP2SWI
Latest Contacts for SP2SWI at QRZ.com
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IZ6TSJ 2015-09-15 20M CW JN63qo Italy Giorgio
EA5AIO 2015-09-15 20M CW IM99tl Spain Jose
ON6KZ 2015-09-12 20M CW JO21la Belgium Peter
IW9HKM 2015-09-05 20M CW JM77mo Italy Daniele
CT1GFQ 2015-09-02 20M CW IM58ko Portugal Carlos
EA5IGL 2015-08-30 20M CW IM97kw Spain Ramon
IZ2DQB 2015-08-27 40M CW JN45ol Italy Frank
IK2RMZ 2015-08-25 20M CW Italy Martin
IT9QAU 2015-08-19 20M CW JM77nm Italy Ferdi
UA3AFO 2015-08-18 20M CW KO85rq Russia Alex
IT9PPG 2015-08-18 20M CW JJ00aa Italy GIUSEPPE PIPARO

Book Totals: 2271 qso's   105 confirmed Get a free logbook at QRZ.COM

World Continents Award#12529
Granted: 2016-04-07 20:55:19   (SP2SWI)

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