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Re: [Amps] Arcing noise in Yaesu amp

To: José Arturo Molina <>,AMP reflector ADD MESSAGE <>
Subject: Re: [Amps] Arcing noise in Yaesu amp
From: Kees - pa7two <>
Date: Fri, 25 Jan 2008 10:44:01 +0000
List-post: <>
Hi Jose, 
I repaired quite a few of these amps, so I can tell you some of the highlights 
of this amplifier that I would like to share with you:
1 - HV Caps were made for 10 years of usage max. This amp is now like 25+ years 
old, these caps make a sissing noise just before they explode.
2 - The filament CT-return is not cut off during RX (add relais!), meaning the 
tank circuit can build up very high voltages during RX. When voltage raises 
high enough, a flash on the band-switch will occure and simply destroy (contact 
actually melt into water drop shape) the contact points, these are pretty small 
in size you see. 
3 - The 22 ohm resistors in the anode anti-parasite L+R (on top of the anode 
cap) are broken.
4 - The 33 ohm resistors in the back compartment (Grid resistors) are broken 
(often one of two after a flash over) or out of range.
5 - One of the many doorknob caps, specially on the anode side (1000pf/3kV) is 
broken. Also in the tank ciruit a quite a few of this type of caps. I have 
replaced many due to the fact that they were out of range due to aging or high 
tempratures or simply broken.
Look at the website of  < PA0FRI >. (search via Google) click on the < QRO > 
option, then at the bottom of the page you'll find < FL2100 > section. Lots of 
text / photo's from my amps. 
I hope this helps finding the fault in your amplifier.
Vy 73, de Kees Member of an all HAM familyAmateurRadio : PA7TWO - M5TWO 
Locator: JO22jp 

> Date: Thu, 24 Jan 2008 22:51:46 -0600> From:> To: 
>> Subject: [Amps] Arcing noise in Yaesu amp> > Hi, I have 
> a Yaesu FL-2100B as my standby linear and I just installed it > because my 
> 30L-1 decided to stay in the transmit mode permanently > (another repair 
> project for later). The amp uses two 572B tubes.> > The Yaesu loads very well 
> but sometimes there is a noise like arcing, > and I haven't been able to 
> pinpoint the origin. Could it be possible to > be coming from inside one of 
> the tubes? I haven's seen any traces of > arcing when I have opened the amp 
> for cleaning.> > If anyone out there has had this same problem, any help will 
> be > appreciated.> > 73,> > Jose Molina, YS1MS> 
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