Fixing a 6 year old 100W transmitter

If you find yourself in possession of an old 100W transmitter that has burnt out, there is light at the end of the tunnel and a high possibility it can be repaired. The one featured here was not looked after very well, dirt, sand, grime you name it had entered the fans and never been cleaned, this caused the fans eventually, after years of continuous use, to cease.

No Fans, No Cooling + Hot Part of World = Components Melted 🙁

The most common component from the 2010 model to fail from overheating was the output filter trimmer capacitors. In a later design change we successfully replaced these trimmers with a stack of fixed chip capacitors to make the amplifier block even more robust in temperatures of +40C.

If the transmitters is in a real mess, full of corrosion, been dropped and bent and generally had a hard life or unskilled engineers or techs have been in there and pulled it apart without knowing of what they’re doing, then it’s days are probably numbered.

If the general condition of the amplifier is good, not too rusty, battered or falling apart, you are handy with a screwdrive and a little electrical knowlege, then it is worth fixing by sending the internal modules back to us, we fix them, then send them back to you for re-installation.

BEFORE DOING THIS PLEASE CHECK THE FOLLOWING

Follow the notes on the picture at the top of this page. Check the:

  • Main transistor on the PLL drive board is quite warm, this is a fair indication that the unit still has drive power
  • 2 way DC terminal block on the main amp block in front of the fan for 48V DC. If you don’t read 48V DC, then carefully remove the red wire from the block, take care it cannot touch ground, the chassis or any other connection and then check the red wire for 48V DC whilst it’s disconnected.
  • 3 way DC terminal block on the amplifier block for 15V DC

If these 3 things are still okay, then take a clear picture of the top of the transmitter, just like the picture here, on the highest resolution you can, email it to us at info@aareff.com and we will send you a price quotation for the repair. It will normally cost three hours of our labour. If the MRF151 main transistor has burnt out, then you will need to pay for that. It is not always the case that the MRF151 has burnt out, quite often it is still intact. The repair will include the upgrade of the 100W AMP BLOCK with the chip capacitors and checking all the other boards.

IF YOU AGREE WITH THE REPAIR QUOTATION THAT WE SENT TO YOU, THEN REMOVE THE MODULES AND SEND THEM BACK TO US

Please follow the instructions in the picture below to remove the 4 modules.

repairing-melted-trimmers-on-old-100w-transmitter-2

When you have the 4 modules out of the enclosure

  • Pack the 4 modules into a box with plenty of soft padding around the top of the amp block. The parcel should only be fairly small and less than 2 Kg / 4.4 LB which means you can use small packet registered or certified airmail, this keeps the cost low
  • Print out the commercial invoice that we sent with the quotation and put it on the outside of the parcel so that customs officials can see it
  • Take it to the post office and send it to:
    AAREFF SYSTEMS / PISANO
    AUT JOAQUIN BALAGUER
    SANTIAGO
    51074
    DOMINICAN REPUBLIC
  • Email us the tracking number

When the parcel arrives with us, we will let you know.

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