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Re: [Amps] Re 200w fast relay

To: Tom W8JI <>
Subject: Re: [Amps] Re 200w fast relay
From: Larry Benko <>
Date: Tue, 10 Jul 2007 10:41:10 -0600
List-post: <>
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 level.

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 relay.

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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