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Re: [Amps] open frame relay rating

To: "Steve Flood" <>, <>
Subject: Re: [Amps] open frame relay rating
From: "jeremy-ca" <>
Date: Sat, 29 Mar 2008 14:38:11 -0400
List-post: <">>
Yes, those are "enclosed" open frame relays. The SB-220 relay is excellent 
and very reliable considering how many still see daily use after 30-40 

Ive never got close to that with a vacuum relay.


----- Original Message ----- 
From: "Steve Flood" <>
To: <>
Sent: Saturday, March 29, 2008 2:31 PM
Subject: Re: [Amps] open frame relay rating

> Thanks Carl and others for the replies.  I don't plan to use this amp 
> above
> 20m actually.  One of my relays is very similar to the SB-220 relay - and
> thinking I'd use the same setup with a third pole for the bias circuit.
> BUT,  I surely do not want to lose any significant signal in RX mode.
> Are the "general pupose" relays considered "open-frame" - I am referring 
> to
> those where you can see the working parts through a clear plastic shell.
> They are used in my Amertiron remote coax switch and Ameritron rates those
> at 4kw HF.
> Steve
> ______________________________________________________
>> Many amps used open frame relays with 10-13A contacts and they worked 
>> well
>> at 1500W. The one issue with them is high VSWR in the thru position on 
>> 10M
>> which can fold back the power in a SS rig. The cure is simple, add a
>> capacitor from the thru loop to ground to tune out the Xl.
>> You can use an adjustable mica trimmer and leave it or measure the value
>> and replace with a 1KV disc ceramic or 500V mica. Typical values are 
>> 25-35
>> pf. Any one will handle 100W with ease.
>> Carl
>> KM1H
> ____________________________________________________
>>>I have several open-frame relays.  If I use one for the T/R relay, what
>>>should the contact rating be for a 1500w amp?   Is it as simple as 1500w 
>>>50 ohms = SQRT of 30A or 5.5 Amps?
>>> Tnx,
>>> Steve, KK7UV
> __________________________________________________
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