lords said:
i would have to go with QRN on this reason why is,
that dam rating is way to weird
25 miliwatt instead of 25 watts
and Mr. bushwacker
hes only going to get 12.6-13.8 volts on the collector leg
depends what he has his power supply set for.
Sometimes even a blown pre driver or final will read on collector for volts.
Right...But you kinda missing the reason for doing this.. If he has no power going into one of those transistors they won't work. Thats how you first check for rf amp problems... first make sure the thing is getting voltage.... then check if theres rf coming out of all 3 stages and trace it all through.
If the transistor is blown it will still read power on the collector.... thats where the power comes into the transistor. What your checking here is to make sure the transistors has enough operating voltage to make it work. If there is no voltage going to the final but the driver and predriver are fine you can get some rf flowing through the final in common emitter design.
Actually I doubt he will see 12 to 13.8 volts on the collector since this radio uses a regulator. Usually that will regulate the power down to around 8 volts. Which is common for a ssb radio.It could be higher with this radio... I have a few around here but I can't remember the voltage... so right now I will assume that its like alot of other regulated radios and has around 8 volts.
If the final is blown you still get voltage on the collector. By checking the voltages, you will know that the transistor is getting enough power and it will also tell you that the regulator is working correctly.
First check the voltages.... then trace the rf. If there is enough operating voltage, you can trace the rf to exactly where the rf drop is.
You have to first check that the rf amp circuit has enough voltage to work properly before you do anything else.
If you trace the rf problem, and find you have no rf (or very low) out of the final... but you have rf going into it... and you know you have the right operating voltage to make it work... then you know there is a problem with the final rf amp. Once you get to this point then you do a quick check of the transistor itself.
Anytime you hook up a radio to work on you should always have an amp meter hooked up in series with the power going to the radio. In this case you could rule out if it is a coax problem or a problem AFTER the rf amp. By simply checking how much current the radio is drawing in TX mode, you can get a good idea that the radio is drawing enough current to put out full power RF.... then you just double check to make sure you have rf coming out of all the stages.
A quick glance at the amp meter will give you a good idea that the radio is drawing enough current to be putting out full power..
When you get a radio in front of you that has problems , you don't just try guessing where the problem is.... you trace the problem through. The first thing you always check if you have a piece of electronics in front of you that isn't working is you check the voltage and make sure its getting enough power to work right.
With all the info I gave him, he should be able to trace the problem through to the exact problem area insted of guessing where the problem is.
With that being said it could very well be a coax problem.. doing all the above checks will tell him if the radio is putting out full power and the problem is outside the radio.
We don't know exactly where the problem is... I gave him the info to trace the problem down to the exact area.
