Repair of SPE EXPERT 1k-fa, Automatic Antenna Tuner

Aug. 2012

My tuner stop tuning on bands with higher frequency than 7 MHz.
It tunes fine on 160 meter and 80 meter, with full power out.

I am a little impressed of SPE, Mr. Dante Specchioli - What a fine and express service from him!

I wrote to SPE, Rom, and Mr. Dante Specchioli  send me a description on, how to remove the ATU from the EXPERT.
This you can find here: ATU_Removal.pdf

Ones before, I had the 1k-fa in Rom, Italy for repair under the warranty, and I can see where they have done some soldering on the boards.

Because of Mr. Dante Specchioli told me, that SPE was starting holly-day until september 1. 2012, and the FIELD-DAY Contest starts at the same time, I will try to find the error my self.

These 2 boards is put together with 9 screws.

No cables between the boards.

The bottom of the boards.

Here you see 3 STAND-UP's in each end of the board, plus 3 STAND-UP's on the PCB.

A total of 9 screws to remove for disassembling.

Bottom of the INDUCTOR-BOARDS.

Upper left corner the 2 ULN2003 has bin desordered and replaced with some new.

   Her I can see, that a new relay is mounted, and NOT aligned perfectly with all the other relays.

  I suspect this relay to be the reason to my faulty ATU.

  NO, not this one, only K29, market with yellow...

Now I have to measure on the ATU, and finding the ERROR...  
Sunday afternoon...
Not the best weather to do the garden.
Turn on the radio ?
No... better try to find the ERROR in my ATU!

Start the lab.power, adjust to 11,5 volt.

Check all the relays on the INDUCTOR BOARD... Does they make a click-sound ?
Yes, Yes, Yes, Yes, No, Yes, Yes... Hej, one did NOT click... :D

This one MUST be defect, K29, same as last time... the yellow marker...

Some times you got lucky...

Relay is removed and PCB is cleaned, ready to mount the new relay.

It look like the diode SM4007 (
the black one ) is broken to.
That could indicate, that I had a lightning storm or some static has killed my ATU..???

Maybe it would be a good idea to switch off the antenna when lightning comes...
Must think about that...   More her...

Tuesday... Measuring the Capacitors:

Relay Calc. pF Measured pF
These are the values I can measure from GROUND to the relays HOTSPOT.

K14B is measured with the relay ON, releasing the relay contact from the capacitors.

I am well aware of my measuring instrument, a homemade PIC-instrument, designed by Phil Rice VK3BHR, could have about -+1 - 2 % difference.

I measure between the HOT SPOT on the relay and GND, and have used some "dill strings" (crocodile) with abt. 30 -40 cm led string, and then I
calibrated the instrument to 0 (zero) pF with one of the led string to GND.

There could bee a little difference, MAX 2 pF in the result, but for K14B I measure 8 pF, and this could bee to mush, if you make a calculation
of 3 x 7,5 pF in series says = 2,5 pF.

A look at the PCB, all 3 capacitors say 10 pF.
So the ATU capacitor board do NOT follow the diagram!

I did lift one legs of C12 and measured the total value to 3.6 pF over these 3 capacitors, so there must bee some added capacitance in this specific relay.

On the other hand, the rest of the measurement look OK in my eyes.

K5B 660 673
K6B 270 299
K7B 78 80
K8B 44 44,8
K14B 2,5 8
K15B 5 5
K16B 11 11
K17B 20,6 19,3
K18B 41,3 43
K19B 80 83,4
K20B 160 163,6
K21B 316,6 331
K22B 636,6 663
K23B 1233 1338

The local Carlo Gavazzi dealer made me a call on the telephone to day, Monday.
They have these relay in stock, price 2 EU pc.  + expenses, more then 30 EU for 2 pcs of relay... Hmmm..??
That's a lot of money for 2 pcs. of relays...
Another local dealer CYPAX have a compatible relay: RT314-12 SCHRACK 1SK 16A 12V 360R PE=20
Not expensive to, abt. 10 EU for 5 pc. all include...
That must bee the case...

NOT waiting on relays anymore...


Thursday the 16. august 2012... The relays is arrived...

ALL IS ON PLACE - ALL IS WORKING - ALL IS OK - 800 WATT out on 6 meter band.


See the pictures here.


Waiting time goes slow...    This is my LAB...
I like to do things myself, experimenting with antenna and stuff... Homemade Spectrum Analyzer, Vector network Analyzer, Software defined radios, 50 MHz homemade analogue radio, PIC-programming and a lot of other things, and for many years.

        My work-life ?   I am retired computer administrator, Danish Customs and Duty - Age 69 years. - More at

On the picture you will find 3 HOTSPOT, with links to the description of the instruments, not all in English.

Homemade Lab. Power supply - Danish Description DG8SAQ - VNWA 2.6 - 1300 MHz VNWA Homemade LC-Meter, Danish description Wavetek Model: 3001 - 500 Mhz Signal Generator TEKTRONIX 200 MHz Oscilloscope Homemade Spectrum Analyzer -> 750 MHz ( OZ3SW, Steen - 1992 ) BJA Print Lab. Powersupply 3 - 30 volt 1 Amp. Frequens Counter Frequens Counter Advanced Instruments LF Signal generator

End of Project...

Click on the picture to see them in full size...