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Author Topic: Ten Tec Century 21 CW rig low output power  (Read 3471 times)
4X1KS
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« on: May 15, 2016, 07:28:52 AM »

anyone got ideas as to why my ten tec century 21 now puts out only 20 watts?  It used to put out 35W.  It sat for a while unused and now it's only 20w out.

Any ideas?

Mark 4x1ks / ku4m
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AA4OO
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« Reply #1 on: May 15, 2016, 02:33:32 PM »

How old is the big cap in the power supply?
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Lower your Power and Raise your expectations
K5LXP
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« Reply #2 on: May 15, 2016, 05:47:41 PM »


Check the DC input cable connectors and fuseholders for voltage drop.  They can oxidize over time.

Mark K5LXP
Albuquerque, NM
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WB2WIK
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« Reply #3 on: May 19, 2016, 03:36:54 PM »

The C/21 uses a power supply regulator that can drift in output voltage and it's set by a resistive voltage divider at a pin of the regulator chip.

I've seen them drift.   I've set my own C/21 to 14.5Vdc output and it runs almost 40W output power. Wink    At the original 12Vdc, it doesn't.   But it's easy to change that.

Of course your particular issue could be something completely different, but I'd measure the power supply voltage first.
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AA4OO
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« Reply #4 on: May 19, 2016, 05:32:29 PM »

I enjoy my old C21

http://www.hamradioqrp.com/2015/10/ten-tec-century-21-cw-only-rig-ahead-of.html
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HAMHOCK75
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« Reply #5 on: May 19, 2016, 11:06:04 PM »

Duplicate thread with one in "boat anchors".

Quote
I've set my own C/21 to 14.5Vdc output and it runs almost 40W output power. Wink    At the original 12Vdc, it doesn't.

I have mine set for 12.8 VDC at the finals. I get 40+ watts on 80, 40, 20M but it drops off to 30 at 28.5-29.0 MHz.
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