[Amps] Emtron DX2 blows ac fuse on going TX

dl4seq at amsat.org dl4seq at amsat.org
Sun Aug 5 15:49:44 EDT 2007


Hello dear OM's

today I made a visit to an om who showed me his new Emtron DX2 Amplifier equipped with two GU-74B tubes. It looked very nice and the blower is very quiet but the problem of this amp surprised me a little:
-For the inrush current he uses "industrial strengt" fuses in the power line distribution inside the house. So he can switch on the amp without blowing the fuse anymore.
-during tx he can nearly send everytime in the LO switch position, but changing to HI switch position the fuse in the ac distribution blows nearly every time in the moment he is starting to send. (This happens sometimes even in LO position.)
-His conclusion of the problem and the 'solutions' he got from other om's nearby and the company selling the PA is: This happens due to the weak german fuses.

So far the story. Personally I don't believe that the fuses are the problem (my Henry 3K classic had only problems with inrush current. On QRO there is no problem with the fuses at pushing PTT). I think there is an error in the (new!) amplifier - most likely in the protection circuit in front of the transformer. Anyway the fuses may be a problem or the entire ac line, so I advised him to test it in the local club station.
But being not the expert I wanted to ask this much valued community for comments here.

Looking forward to your answers and vy 73!
Markus, DL4SEQ.



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