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Re: [Amps] keying issue resolved

To: ka9egw@ka9egw.com, amps@contesting.com
Subject: Re: [Amps] keying issue resolved
From: Jim Garland <4cx250b@miamioh.edu>
Date: Wed, 28 Dec 2016 08:14:10 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Yes, an optically coupled MOSFET relay will work fine, and is what I use in my StationPro keying circuit. Two other considerations are the on-state resistance and the switching time. The PLA140 relay which I use has a maximum on-state resistance of 8 ohms. Relay data sheets always include this info.
73,
Jim W8ZR

On 12/28/2016 8:04 AM, ka9egw@ka9egw.com wrote:

You make a good point…but I was thinking a MOSFET-output AC/DC SSR…

*From:*Jim Garland [mailto:4cx250b@miamioh.edu]
*Sent:* Wednesday, December 28, 2016 8:37 AM
*To:* ka9egw@ka9egw.com; amps@contesting.com
*Subject:* Re: [Amps] keying issue resolved

Better be careful, Brian! Most AC solid state relays use thyristors for switching and depend on the zero crossing of the AC load to switch off. In other words, if you try to use one of those relays to key a DC voltage, such as in the 30L1, it will key up the amplifier but won't turn it off when the control voltage is removed. Also, if I recall correctly, some solid state relays have minimum load requirements, which you might not reach with a big 30A power relay. Personally, I think you need a better solution than what you're intending.
73,

Jim W8ZR


On 12/28/2016 7:17 AM, ka9egw@ka9egw.com <mailto:ka9egw@ka9egw.com> wrote:

    My sincere thanks to all who responded.  After serious consideration I got

    inspired to keep it simple-a 240VAC 30A solid state relay with the low side

    of the 3-32VDC input pulled to ground by any of several radios will

    facilitate keying the +160VDC-keyed-line 30L-1, and also the

    6.3VAC-keyed-line Hunter 2000C [which some say is the amp the 30L-1 could

    have and should have been], and also the Dow-Key relays on the Heath

    Warrior.

    Thanks to all who responded!

    73, Brian KA9EGW

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