Introduction Amateur radio VKVPA – June 2022

VKVPA – June 2022

Kenwood TS-2000 s SDR panadaptérom v N1MM
Kenwood TS-2000 SDR panadapter v N1MM

Something new again, again something does not work and yet a record result of VKVPA. I tried the Kenwood TS-2000 in the previous round. It is known about him, that he has some flaws, but provides power at 2m up to 100W, speech processor and several filters, which help combat interference.

TIP: why make adjustments in Kenwood TS-2000?

Problematic Kenwood TS-2000 filters

A certain series of this TCVR has problematic filters on 455 kHz. It's not just the TS-2000 that suffers, but also devices of other brands. This is manifested by a crack in the income, dropout to complete loss of sensitivity. The owner of the device will have to service the device inadvertently.

Low sensitivity to 144 MHz

The second reason why adjustments are made in this device is the low sensitivity to 144 MHz. This is due to the low voltage on the g2 preamplifier. It applies again, that some versions have the preamplifier operating point set differently and the sensitivity is OK.

Fan replacement

The fan in the TS-2000 also turns on and receives. Even during reception, many circuits are powered and the device generates heat. If the fan control circuit evaluates, that the temperature is high, the fan turns on. However, the original fan is relatively noisy. Therefore, it is advisable to replace it with a silent fan, for example, Noctua.

Filter INRAD

To improve the reception and increase the resistance, it is possible to replace the factory filter on the frequency 10,695 MHz. Filter INRAD #92 it is narrower and has a better stop band, but installation in the device is in the form of cable connection.

SDR adapter

All TCVRs of the modern generation are characterized by the possibility of displaying the frequency spectrum using SDR technology. However, the TS-2000 is not this generation, but by adding a decoupling amplifier and an SDR receiver, this option can also be obtained.

There are quite a few reasons for some intervention in this device.

Improvements before VKVPA

Right after the last round of VKVPA, I started to edit the source. It was not designed for the required current consumption. I added two more to the pair of stabilizing transistors in the source, thereby improving the heat dissipation distribution while reducing the internal resistance of the source.

It's also time to use it headset with microphone and footswitch. The connection is described in another article.

I also planted silent fan Noctua NF-R8 redux 1200. The difference in noise compared to the original fan is significant. The same fan also replaced the classic Sunon fan in the home source 13.8V / 40A.

I composed isolating amplifier according to G4HUP. Ide o similar amplifier as I installed in R2CW TCVR, however, this is also supplemented by an output low-pass filter. The isolating amplifier is fed in front of the frequency filter 41,895 MHz. I made a mistake here and accidentally connected it behind the filter. So I saw probably on SD 15 kHz spectrum. When I realized the mistake, so of course I changed the connection point, however, after passing the TCVR, it turned on, but he was completely deaf.

Finding the cause took several hours to find and measure. It was interesting, that TCVR did not even broadcast in modes other than FM. I was able to find out, that most RF receiver circuits work, but there is no convection on 455 kHz. An oscillator signal did not enter the mixer. This is created by DDS. Transmitter circuits have similar DDS circuits. They also need a clock signal for their function – and he was missing. A clock signal is generated on the PLL board, but it goes to the adjacent RX2 board, where there is still a single transistor amplifier. While on the PLL board I measured with a HF probe approx. 410mV, just a few millivolts behind this transistor. Why? Because he had no power. Power is supplied by a flat cable from the RX1 board. Due to manipulation in TCVR- I ejected the cable several times and inserted it into the connector. It's a paradox, that the supply voltage is approximately in the middle of this cable. The ohmic measurement showed no error in the cable. However, the experimental connection with a separate cable revived the TS-2000. Uff.

I made one more improvement – CAT control from N1MM +.


The weather forecast promised the sun, heat and wind. It came out perfectly. It was visible from a distance, that the propeller of a wind power plant on the nearby Suchý vrch is spinning fast. I judged, that I will still succeed 4x5el.DK7ZB yagi get in the air. Veruže also succeeded. It was harder to build a single 8el.DK7ZB yagi on the second mast. The wind spun her as he pleased.

Thanks to the improvements and the acquired skill with the construction of antennas, I had everything ready in advance. She remained to calibrate the rotator. I'll turn it on – and does not spin. I meant, that I dream. Oh no. It's not spinning. So I manually set the antennas to 180 degrees.

VKVPA is starting and I'm still finding out some problem with modulation. Maybe it's a headset with a microphone, possible TCVR, maybe the source… I do not know yet. Wind stronger and with one hand hold the pole with 8el.DK7ZB, write the second one, operate the device as well as KST chat… and a handheld microphone? I tried to reset the modulation (performance reduction and modulation, although the ALC was almost unnoticed).

Detail SDR specs VKVPA v N1MM +
Detail SDR specs VKVPA v N1MM +

A significant plus, however, is the CAT associated with SDR. I practically miss any signal. Not in a moment, when the station is not broadcasting and I would tune in through it. I saw her on the spectrum, so I'll wait for her on the frequency moment.

The activity from the southeast is relatively significant. Whether it is Romanian, Hungarian, Serbian or Bonian stations. And even on challenge. Probably a team, that these stations are away from the epicenter of activity, so they search more in the band and more actively shoot antennas here as well. They are also valuable multipliers for me.

Directions in VKVPA June 2022
Directions in VKVPA June 2022

When calling one call, the station ending sounded “/4”. After getting hooked, he came out of it I5MZY / 4 with JN64. I tried both antennas, but the square was turned away and it was on both sides equally. However, the connection was successful. I contacted two other Italian stations via KST chat IK4GNG actually passed!

I turned by hand for the last half hour 4x5el.DK7ZB yagi to azimuth asi 270 degrees and tested more Czech and Moravian stations. Apparently, German stations were also on the band, but the wind was so strong, that sometimes I held the mast with both hands, but did not spin. It also blew into the microphone.

Map of VKVPA locators June 2022
Map of VKVPA locators June 2022
DXCC land in VKVPA June 2022
DXCC land in VKVPA June 2022

Physically, it was a very demanding VKVPA. The left shoulder was perhaps still. But as a result, this VKVPA is a record – managed to 74 link, 266 points and 22 násobičov, which gives 5852 points. He also rose mileage, a to na 204. The longest connection is IK4GNG (657 km).

It will be essential now to solve the problems – repair the rotator or use another one and find out why the modulation was wrong. Thank you so much for the multiplier, for example OM2JK for JN87 or OM8OM for KN09!