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Re: [Amps] Re 200w fast relay

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Subject: Re: [Amps] Re 200w fast relay
From: "Peter Voelpel" <>
Date: Tue, 10 Jul 2007 19:10:44 +0200
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Are you sure to talk about the S2 relay formerly manufactured by SDS?
It works much longer at 1KW+ in TL922, SB-220s and L4Bs on qsk then the
Jennings RJ1 vacuum relay before the contacts are gone.

The DS2E relay family is different and cost a lot less


-----Original Message-----
From: [] On
Behalf Of Larry Benko
Sent: Dienstag, 10. Juli 2007 18:41
To: Tom W8JI
Cc: Amps Amps
Subject: Re: [Amps] Re 200w fast relay

Hi folks,

I recently retired after many years designing telecom equipment and used the
Aromat DS2 and DS2E relays extensively.  The gear I designed probably used
over 100 million of the relays in total over a 15 year period.  We did
exhaustive tests of this family of relays from Aromat (now NAIS) and their
competitors such as P&B, CP Clare, American Zettler etc.  In all the cases
the Aromat relays were best but always a few pennies more costly.
There are a couple of incorrect statements being made here.

1.) The relay contact is bifurcated and is gold clad silver. The maximum
current ratings are 2A @30V DC and drops to 0.6A at 120V AC 60Hz and 120V
DC.  It is not a 3.5A contact.  The bifurcated contacts are super for for
level receive circuits and this relay was the relay of choice when switching
currents were in the uA region and before the super small TQ and TF families
were created.
2.) Relays are like people.  Abuse them and their life expectancy decreases.
The DS2 relays when used within their ratings had life expectancies in
excess of 20 million (where we stopped testing).  We did tests at up to 5A
for the relays and provided we did cold switching or switching with currents
(not RF) in the hundreds on mA. the relays did survive to the 1 million

I have a ton of these relays in my basement and have used them at RF for
lots of stuff.  The biggest problem I have with them is in a 50 ohm circuit
the isolation to the open contact is not good.

I just measured a DS2E-M-DC12V with an HP8753B/85046A network analyzer. 
With the analyzer calibrated to the relay and terminating the unused contact
to ground gave the following results.

Insertion loss: 0.051dB @ 30MHz, 0.125dB @ 200MHz
SWR: 1.10 @ 30MHz, 1.38 @ 200MHz
Isolation to unused contact: 46.2dB @ 30MHz, 28.1dB @ 200MHz.

Measurements were made from the common contact to both the normally open and
normally closed contact with the relay energized and de-energized.  
The results shown above were the averages of the 2 sets of measurements
which were similar except for the isolation measurement which varied about 4
dB due to the no-symmetrical arrangement of the physical layout of the

Larry, W0QE

Tom W8JI wrote:
>> Schematic in mine for the output SPDT relay calls it an 
>> AZ2735-08-2 - dunno if thats a TT number or mfr's nr.
> This is an especially good tip. While that isn't a good PN, 
> it led me to American Zettler has some very cheap fast 
> relays.
> I'll get some samples and advise how they work. 
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