I ordered the filter kit. After a few days it arrived and I unpacked it. Everything was there and in good order.

I Wanted to test two things, the filter characteristics, and the controlling of the relays on the board.

 

Controlling the relays.

I have an Arduino Mega 2560, and I uploaded the most simple Sketch in it, blinking the led on the board and output D13 . See the site of Arduino. I use IDE as programming environment.

I powered up the filter board with 12V and connected the Arduino D13 to the correct input of the filter board. For that I made a flat cable with the female connector and split the cable into one V+ (12V), two GND and the other wires are for the 7 filters.

You need to put a TTL 'high' on the filter input to close the relays. One input controls two relays. One relay has about 350 Ohm resistance, so two of them in parallel are about 175 Ohm. The two relays draw about 2 x 35 mA, so 70mA. This is easily delivered by the driver ic ULN2003.

I realized it, using a breadboard, see the photograph. At the front left the Arduino, in the middle the breadboard, at the right the filter. At the right upper the Marconi signal generator. On top of it an RSP1a WebSDR radio, with the Spectrum analyzer software on my PC.

 

I connected the D13 wire to filter nr one. It worked fine until it stopped working,......the open collector of the ULN2003 was burned,.... I tried the filter nr. 2

It worked, but also burned after ten clicks of the relays.

This was not what I expected,.....after studying all the components and checking all the connections of the components on the board, I was wondering why the open collectors of the chip were failing. I am pretty sure that it is the lack of a spike surging diode over the relays. It is common to add these diodes and in the chip there are those diodes available ! Look for pin 9 ! Not connected.

I mailed Razvan (where I bought the kit from) and are in discussion with him, how to solve this problem asap.

In the meantime I ordered some new ULN2003's at Reichelt, and to be sure soldered over all the relays input pins a 1N4148 diode. Make sure the cathode (+) is connected to the plus, V+, 12V. After getting the chips delivered, I will also connect the pin 9 to the V+, 12V. Double check,....

Razvan issued an update to all his customers, so the issue is solved.

Later on I ordered the back panel. It has also three relais, and I saw that the update (connecting pin 9 to V+) was already done on this module.

The filter curves were measured and they were roughly according to the specs documented on the site of Razvan.

filters PA Razvan, measured by me:

                Freq       Pass        3dB          3e harm    dip (<-50dB)
160m:  1.8MHz  -0.30dB    3.0MHz     <-40dB
  80m:  3.5MHz  -0.30dB    6.1MHz     <-50dB
  60m:  5.3MHz  -0.10dB    9.3MHz     <-42dB
  40m:  7.0MHz  -0.10dB    9.3MHz     <-42dB                             same filter as 60m
  30m: 10.0MHz  -0.25dB  17.6MHz    <-52dB
  20m: 14.0MHz  -0.25dB  17.6MHz    <-54dB                             same filter as 30m
  17m: 18.1MHz  -0.30dB  28.9MHz    <-54dB

  15m: 21.0MHz  -0.10dB  28.9MHz    <-48dB   55.8MHz (must be 63MHz) same                                                                                                                                         filter  as 17m
  12m: 24.9MHz  -0.30dB  40.0MHz    <-42dB   64.8MHz (must be 74.7MHz)
  10m: 28.0MHz  -0.25dB  40.0MHz    <-37dB   64.8MHz (must be 84MHz) same 

                                                                                                                               filter as 12m
    6m: 50.3MHz  -1.0dB    80.0MHz    <-52dB 155 MHz (must be 151MHz)
    4m: 70.0MHz  -0.1dB    80.0MHz    <-55dB 210 MHz (more dips, is ok) same

                                                                                                                                filter als 6m

So, basically the filter is doing ok, so enough for now.