[Amps] Soft Start

[Jim W7RY]

Soft start (I call it step start) does reduce filament inrush current. As 
long as it's on the filament transformer primary.

Which it is in the SB200, SB220, TL922, L4B and TenTec Titan... And many 
others.

73
Jim W7RY


-----Original Message----- 
From: Kim Elmore
Sent: Tuesday, December 26, 2017 9:58 PM
To: Warren Volz
Cc: amps at contesting.com
Subject: Re: [Amps] Soft Start

A related question. Once long ago I read that power cycles are very hard on 
filaments. Is that also the case with soft starts, or does the soft start 
reduce the thermal shock issues?

Kim N5OP

"People that make music together cannot be enemies, at least as long as the 
music lasts." -- Paul Hindemith

> On Dec 26, 2017, at 21:08, Warren Volz <warren at warrenvolz.com> wrote:
>
> I’d recommend a step start with fuses. I have w7ry’s board in my sb220 and 
> the fuses saved me from a bad tube once already.
>
> -Warren
>
>> On Dec 26, 2017, at 8:59 PM, Jim W7RY <jimw7ry at gmail.com> wrote:
>>
>> I recommend 10 Ohms. I use 2 resistors and 2 relays. There are fuses in 
>> series with the resistors to protect them.
>>
>> Why would a cap blowing up cause an issue with a step start circuit?
>>
>> Again, I use 2 resistors and 2 relays on a small circuit board.
>>
>> See:
>>
>> https://www.ebay.com/itm/282765541853?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
>>
>> 73
>> Jim W7RY
>>
>>
>>
>>
>>
>> -----Original Message----- From: Arnie Pfingst
>> Sent: Tuesday, December 26, 2017 8:31 PM
>> To: amps at contesting.com
>> Subject: [Amps] Soft Start
>>
>> Once upon a time, i had a capacitor explode upon start up. I've heard 
>> stories for and against adding a soft start circuit to my 
>> amplifiers.(Some say 20 ohm resistors, and others say 30 or 40 ohm.) That 
>> and the price of replacement tubes. In my case i have two TL 922a amps 
>> using 3-500z tubes.
>> Both set up on 240vac. What do you all have to say here. Thanks
>> Arnie
>>
>>
>>
>> Sent via the Samsung Galaxy S8 Active, an AT&T 4G LTE smartphone
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