XFORCE 40012 BASE ISSUES

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movrider
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XFORCE 40012 BASE ISSUES

#406513

Post by movrider »

I have a XFORCE 40012 base that was built for me in July 2015 with PP100's and regulated power supplies, I had to have it re-pilled the first time after about 3 years and used a matched set of 4 of the HG 2SC2879's after it burned a couple of the 1/4 watt resistors, also replaced the discolored 2 watt resistor across the input combiner. It had never seen more than 38-40 watts pep so just figured it was those junk PP100's... long story shortened a bit. It was re-pilled again about a year later under same circumstances. Now am preparing to do it one more time once again after about another year, this time I may have been to blame hitting it with 100-125 pep from my Stonewall as it toasted the 2 watt resistor across the input combiner this time, I found the body of that resistor was actually touching the ferrite core for the combiner and scorched it a bit as well as melted the wire wraps so it looks like I will be wrapping a new ferrite core and the power transformers on the input side.

Does anybody happen to know whether I should be using Type 43 or Type 61 ferrite core for that input combiner?

Another question I have is... Am I missing something here? during all this studying of the situation I noticed that the output combiner has no resistor across it like most of the pic's/videos I have seen, could this be part of my issues?

The attached pic was from 2018 before it was re-pilled the first time.
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Crusher
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Re: XFORCE 40012 BASE ISSUES

#406622

Post by Crusher »

Both the input and output combiners should be 61 type ferrite. The resistor across the combiners is there to tell you there is an issue. They should both have a 100 ohm 2W resistor across. Dropping in new transistors, you may have to retune it some. As the pp100’s and the HG’s Tune a little different.
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movrider
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Re: XFORCE 40012 BASE ISSUES

#406764

Post by movrider »

Replaced the pills and 1/4 watt resistors again, rewrapped the input transformers and wrapped up a new Type 61 ferrite core for the input combiner and replaced the toasted 2 watt 100 ohm resistor and she is back in business. Not sure if I got lucky or what but it appears I have a little lower reflect and about 50 watts additional pep output... we will see how she holds up!



Next time I have problems with this **Censored** I think I will send it to Carl for a re-work with the HG 2SC2879-C transistors.
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Crusher
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Re: XFORCE 40012 BASE ISSUES

#406770

Post by Crusher »

Using 61 transformers on input instead of the 43 type in their now. Input reflect will be lower and you’ll see a little more output.
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