[Amps] Relays for RF switching

[VE6JY Don Moman]

 I would suggest using the encapsulated sealed relays such as the Potter and
Brumfield RKS-5DW-12 (about 8$ in Canada) or the lighter rated - and cheaper
($C2.50) Aromat JS1E-12v.  I think both are in the DigiKey catalogue.  Both
have given excellent service at legal limit at HF, indoors and out for up to
10 years (so far) with no failures.  The P&B ones are used in the DX
Engineering remote relay box I have which is rated to 5 KW.  I have used
other misc relays in the junk box that have worked fine, the exception was
another one of the lower voltage high current power relays you mentioned.
As I recall (it was several years ago) it had poor SWR or isolation when
tested so didn't use it.  There must be significantly poorer dielectric
and/or insulating properties in these relays when used at RF.

73 Don
VE6JY


----- Original Message ----- 
From: "Vic Rosenthal" <vic at rakefet.com>
To: "Amps reflector" <amps at contesting.com>
Sent: Thursday, April 15, 2004 05:11
Subject: [Amps] Relays for RF switching


> I needed a remote (indoor) antenna switching unit, and since I had
> everything I needed in my junkbox, I decided to build it instead of
> paying $140+ to Ameritron.  I used some relays that I had purchased from
> All Electronics for $1.50 each; they are "power relays" with contacts
> rated 15a at 120 VAC.  After all, 1500 watts into a 50 ohm line is only
> about 280 volts and 5.3 amps.
>
> Hey, if it worked I'd be in the miser's hall of fame.  However, what
> happened is that the relays got quite hot after about 15 seconds at the
> 1500 watt level.  They are enclosed in little plastic boxes, but it's
> possible to touch the bottom of the armature and it is hot enough that I
> am afraid of what would happen in a contest or long rag chew.
>
> I'm wondering if anyone has ever done anything like this, and if so,
> what kind of relays they used.  Or, if someone has an Ameritron unit
> handy, if you would be so kind as to look inside and see what kind of
> relay they use.
>
> I'm also curious as to why the relays heat up.
>
> -- 
> 73,
> Vic, K2VCO
> Fresno CA
> http://www.qsl.net/k2vco
>
>
>
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