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Author Topic: Tempo One - Part Identification please!  (Read 798 times)
N1GMV
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Posts: 68




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« on: November 22, 2001, 06:00:24 PM »

Greetings,
I have a Tempo One and accidentally let some smoke out of a component. I have no clue whether it is blown or not or if I blew the PA's

The part is the square maroon colored block that goes from the Plate Variable Cap to the top of the HV coil.
It says 501K30 TV6KV on it.

I am getting only 10-20 watts out of the rig when the IC is up at around 200, something is definately wrong. Was tuning into a dummy load when this happened.

Any suggestions on how to test this component? Why it smoked? Hope my tubes are not blown!
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WB2WIK
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Posts: 20603




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« Reply #1 on: November 26, 2001, 02:21:44 PM »

I haven't had my hands on a Tempo One in many years, but from your description this sounds like the plate blocking capacitor, which isolates the HV power supply from the plate tank circuit while coupling RF from the PA tube plates to that same circuit.

It may have failed simply from old age...the Tempo One is a nearly 30 year-old rig.  Or, it would be very stressed if you tried loading the rig into "no antenna," or a higher impedance antenna than the pi-net output circuit can handle.  Try replacing it with a .001uF, 2500Vdc (or higher voltage rating) ceramic disk capacitor and give it a go, again.  Don't skimp on the voltage rating of this capacitor -- the actual (DC + peak RF) voltage across it is MUCH higher than the DC voltage of the Tempo One's power supply.

73 de Steve WB2WIK/6
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W9GB
Member

Posts: 2623




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« Reply #2 on: November 26, 2001, 03:11:29 PM »


> The part is the square maroon colored block that
> goes from the Plate Variable Cap to the top of the HV
> coil.
> It says 501K30 TV6KV on it.

It is a capacitor.  Rated at 6 kV (6,000 volt)
A 601 is .10 , so it appears (501) to be a .01 value.

w9gb

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N1GMV
Member

Posts: 68




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« Reply #3 on: November 26, 2001, 08:45:10 PM »

Okay, brought the rig to a friends place and we replaced the cap with a 500PF 3KV mica. That did the trick!! 150 watts out. Thank god the tubes are good!
Thanks for your help guys.
73
John, N1GMV
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WB2CIR
Member

Posts: 13




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« Reply #4 on: December 05, 2001, 03:26:32 PM »

Just to summarize:

W9GB identified the blown cap as a .01 uF (10,000 pF), 6 KV
WB2WIK recommended a .001 uF (1000 pF),  2.5 KV (or higher voltage rating) ceramic disk capacitor
N1GMV used a .0005 uF (500 pF ) 3KV mica

I would research mica vs. ceramic, etc.  I think the mica is a higher quality capacitor (?).  The plate blocking capacitor is an easy to access capacitor, so I would look for a bigger one, and upgrade it when you get a chance.

Theoretically, the smaller uF should leave less RF for the antenna, and be most detrimental at 80 meters.  The smaller voltage rating will stress the capacitor, so maybe it will only last 10 years instead of 30 years.

Just in case the Tempo finds a new home someday (or you lose your memory), you should notate the value change in the Manual.

-N-
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KC8YXA
Member

Posts: 14




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« Reply #5 on: January 30, 2004, 11:30:45 PM »

My T-1 did the same thing years ago replaced the part and is running just fine.
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