[SixClub] Amplifier Questions...

[Peter Chase]

Just check the input to each final and compare it to its output.  You should have a notable  increase at the output of each .  You should look up the RF device so you know what to expect for power output and what the normal parameters are.  this can be done with basic test equipment.  Hope this helps.

Regards

Pete N1JHF
 
> From: kb0nly at mchsi.com
> To: sixclub at mailman.qth.net
> Date: Fri, 4 Jun 2010 11:45:27 -0500
> Subject: [SixClub] Amplifier Questions...
> 
> I know this is OT, but there is a lot of smart cookies on here and the other 
> reflectors I have tried, like the AMPS reflector just don't get any replies 
> like here...
> 
> Questions..
> 
> 1. I have a UHF amp I'm working on, a RF Concepts 4-110. I think the 
> finals are bad, but need someone to verify my bad memory. When testing 
> these bipolar transistors the collector-base and base-emitter junctions 
> should test as a diode correct? I have a dead short from base to collector 
> so that seems to verify they are fried. And the emitter-collector has to be 
> open in both directions, well of course its not because of the dead short to 
> the base.
> 
> 2. It's been a while since I worked on a solid state amp... Whats the 
> package type of the small capacitors used on the finals, those little square 
> metal jobs with a tab out of one side. For the life of me I can't remember 
> the package number so I can go catalog search for some new ones, as I'm sure 
> they need replacement after the heating they took on removal. Also, the 
> marking on them, in this case 30 and 40, I believe that's in pF correct?
> 
> 3. This amp has a bias adjust for each transistor, what is the best way to 
> adjust the bias after replacing the transistors, just set for minimum idle 
> current or is there a number I should be shooting for? No specs available 
> from RF Concepts unfortunately but I was able to actually find a one page 
> schematic at least.
> 
> 73,
> 
> Scott 
> 
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