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Author Topic: Ten Tec Century 21 CW rig low output power  (Read 5374 times)

4X1KS

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Ten Tec Century 21 CW rig low output power
« 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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RE: Ten Tec Century 21 CW rig low output power
« Reply #1 on: May 15, 2016, 02:33:32 PM »

How old is the big cap in the power supply?
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K5LXP

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RE: Ten Tec Century 21 CW rig low output power
« 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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RE: Ten Tec Century 21 CW rig low output power
« 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. ;)    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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HAMHOCK75

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RE: Ten Tec Century 21 CW rig low output power
« 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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