- #WHAT IS ACTUALLY INSIDE A FAKE 2N3055 TRANSISTOR DRIVERS#
- #WHAT IS ACTUALLY INSIDE A FAKE 2N3055 TRANSISTOR DRIVER#
- #WHAT IS ACTUALLY INSIDE A FAKE 2N3055 TRANSISTOR PLUS#
My guess it's either 'dodgy transistors' or the RF feedback components between collector base, it could also be due to the biasing components. Should you decide to fit another pair, I would leave it in TX mode with NO DRIVE for a short while to see what happens, keeping a check on the temperature of it.
#WHAT IS ACTUALLY INSIDE A FAKE 2N3055 TRANSISTOR DRIVERS#
The pushpull drivers 2SC1972 has no emitter resistors, thus does not need isolating. should it short out the transisor will over-run due to too much gain, take off or suffer from thermal run-away.
#WHAT IS ACTUALLY INSIDE A FAKE 2N3055 TRANSISTOR DRIVER#
The single ended driver 2SC1971 has a emitter resistor, since the metal tab is the emitter a mica is used to prevent it shorting out. It could of course be the negative feedback components, possibly causing them to 'take off' due to the higher gain. I would only get these from reputable sources, Eleflow thats the place to get them from, they have a outlet in the UK If the biasing is right there is no reason for it to blow, unless it's running into a faulty load which could happen should one of the components breaks down feeding the next stage or the transistor is being over-driven. There are many fakes transistors kicking about, so the first question HAS got to be where did you buy it from? A search for fake or counterfeit RF transistors will bring loads of 'hits', it's not only RF transistors that are 'faked' these day's. I really don't want to admit defeat on this one - but I suspect it maybe something inherent with the TS2000 and certain batches of 2SC1972's. I can only think that maybe C29 and C30 which are 0.1uF feedback caps from collector to base might be intermittently faulty under RF drive conditions or some other bypass cap is faulty causing the whole driver to burst into oscillation perhaps ? The batch number of the failed replacements is 03B-C.
#WHAT IS ACTUALLY INSIDE A FAKE 2N3055 TRANSISTOR PLUS#
I'm reluctant to buy another pair of drivers as they may also fail, plus they'd likely come from the same batch.
The darn transistors had failed after only a few minutes !!įurther checks revealed that the bias circuitry was still good but the 2SC1972's had gone leaky and the Vbe was now 5V. Power output was good on 144MHz and was just about to pat myself on the back for another job well done when the power dropped back to 5 watts ! I carefully checked around the PA PCB to make sure everything else was ok especially the operation of the bias circuitry before installing them.Īfter installation I had the bias set to minimum so as not to over dissipate them then gradually turned up the bias till the current increased by 150mA (much less than specified in the service manual). Quickly determined it was the 2SC1972 drivers which had failed so I ordered a replacement set. I offered to repair a TS2000 for a local ham friend for the cots of parts only.įault was low output (<5 watts) on HF, 6M and 144MHz but 432MHz was ok.
0 kommentar(er)
