[Amps] Metcal contact with MOV?

[John T. M. Lyles]

The contacts of the Metal tip happen to be a coaxial connector, with 
13.56 MHz RF power. I don't believe it would be wise to put MOV 
across that, due to the stray capacitance of the MOV and the RF 
voltage in that resonant circuit around the induction coil. The 
coaxial structure is a bit fragile, but the Metcal has done some 
amazing engineering to get those stations to work so well.

John
K5PRO



>
>Date: Wed, 17 Sep 2003 05:16:19 -0700
>From: rlm <r at somis.org>
>To: "Steve Thompson" <g8gsq at qsl.net>, "AMPS" <amps at contesting.com>
>Subject: Re: [Amps] Metcal soldering iron and microscopes
>Message-ID: <200309171205.h8HC5Tfh028969 at contesting.com>
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>
>
>>On Monday 15 September 2003 16:53, John T. M. Lyles wrote:
>>snip
>>>.... I also got a Metcal RF soldering iron for about
>>>  $25 from a local junk dealer.
>>How to ruin someone's day!!! :-) I bought two of these for work, at full
>>price
>>:-(((
>>
>>Seriously, I think they're great except that I've had several bits go
>>intermittent long before they were worn out. I suspected the contacts in the
>>handle but I'm far from certain.
>>
>Ä  A small MOV across the contacts will protect the contacts from
>arc-damage.