FT101E C13 C104

[357]

I tested both these and they came up as 112PF 17 ohms
The word on the street is to change C13 before it goes bad, looks like people should do C104 too.

Anyone know what tolerance these are?

 

[BBB]

Page 68 of this ARRL write up mentions C13 as 80-pF at 1 KV. Maybe an upgrade from the 500 volt factory supplied cap. No mention of any other specs of this cap there.

http://www.arrl.org/files/file/Technology/pdf/9905068.pdf

Saw this mentioned also about C131:

"Add C13 80pf 1kv and C131 1000pf 1kv (the factory installed capacitor is 500volts) to your order. One is a coupling cap from the driver tube to the PA tubes and the other looks to be feedback. Degradation causes high tube bias and excessive heat. This was advised by a FoxTango contributor. These are below the electrolytic cap list."

http://ppinyot.com/y/yaesu.htm

 

[Radio Tech]

You don't have to be too specific on the tolerance of the caps. But just replace them with silver dip 1kc caps of same value. Do C13 (80pf) and C131 (1000pf). But add a 0.01uf ceramic disk in series with both of those caps.

The main reason for changing them before they go bad is that these old mica caps mostly fail short instead of open. When they short they WILL cause some nasty damage to the rig. Also while you are in there go ahead and ad a BT127 diode in series with the grid resistor R14.

With those 2 ceramic caps and the diode added you are now protected in case of tube flash over.

 

[357]

I pulled and replaced C13 and it tested 92pf when it was free and clear.
Goes to show testing with just 1 leg undone doesn't give a accurate reading.
It showed 112pf half in circuit