[Icom] More on isolation relay with non-ICOM amps

[Larry Benko]

Larry,

I won't make this too long since it is not really an Icom topic.
I have extensive experience in the telephone industry using relays
of all types.  Years ago I built a homemade keyer using a Western
Electric mercury wetted relay for the mechanism to key the rig.  I
operated the relay at 50 wpm (not actually keying the rig) 100%
dots for several weeks just for fun since the relays were free.  The
relay was just fine.  I calculated the relay had done 200 million
operations.  I have used many small reed relays and as long as you
don't weld the contacts by exceeding their rating they are often good
for a billion operations.  The manufacturers regularly will guarantee
several hundred million operations if you are a really big customer.
Don't worry about it.

73,
Larry, W0QE

W3UIO wrote:
> --- Adam Farson <farson@shaw.ca> wrote:
> 
>>Hi Larry,
>>
>>If you can e-mail me a scan of the interface
>>schematic you mentioned, I
>>shall be able to create a Webpage for it, and upload
>>it to the Icom FAQ site
>>as a subsidiary page to "On External Keying Relays".
> 
> 
> Sounds good to me.
>  
> 
>>I worked in the telephone-switching industry for
>>many years prior to
>>retiring 3 years ago.  We used various types of reed
>>relays as impulsing
>>("A") relays in trunk interface circuits for
>>telephone exchanges. The most
>>arduous application was dial-pulse sending at 10 pps
>>(600 ops/min,
>>equivalent to 20 wpm QSK CW.) Typical contact-load
>>parameters were 50 ~ 100
>>mA at 50V DC. I do not recall one impulsing relay
>>ever failing in our lab;
> 
> 
> What about the typical contester sending at 35 - 40
> wpm with a relay rated for 10 wpm, or am I missing
> something?
> 
> <snip> 
> 
>>I recall our component guys testing reed relays at
>>20 pulses/sec for an
>>application in Japan, which uses both 10 and 20 pps
>>dialling. 20 pps equates
>>to 1200 ops/min, or 4 times the OMR-109 spec. They
>>observed some pulse
>>distortion at the higher impulsing speed, but
>>accelerated life tests did not
>>indicate any significant increase in contact
>>degradation over time, as
>>compared to 10 pps testing. (pps = pulses/sec).
>>
>>From a perusal of the reed-relay literature, I have
>>noted that many of the
>>vendors state expected-life figures as minimum
>>values. For the case of the
>>OMR-109F, the stated no-load value of 100 million
>>ops equates to 5555 hours
>>of QSK CW keying at 10 wpm. Even if the life
>>"number" is not a minimum, 5555
>>hours adds up to a lot of on-air time! Per the
>>OMR-109 data sheet, this
>>figure is reduced by 50% at 5 ~ 10mA/12V (still a
>>pretty respectable number
>>of operating hours.) Higher load voltage/current
>>will reduce the expected
>>life even further, as can be seen from the data
>>sheet.
>>
>>Our experience with these relays in telephony
>>applications, as described
>>above, suggests that the expected-life spec is
>>indeed a minimum. Thus, I
>>believe that projected reed-relay life will probably
>>not be an issue with a
>>light load (e.g. 5mA/12V.)  A simple transistor
>>buffer circuit between the
>>exciter relay and the amplifier keying line will
>>accomplish this, whilst
>>eliminating the latency associated with an auxiliary
>>relay.
>>
>>It seems improbable to me that the product planners,
>>designers and component
>>engineers at Icom would have expended precious R&D
>>resources to provide QSK
>>CW in their higher-end HF transceivers, only to
>>knowingly compromise this
>>feature by specifying a relay which would, in
>>effect, put an expiry date on
>>it.
> 
> 
> Does this suggest that Alpha Power is incorrect in
> their diagnosis of the cause of relay failure?
> 
> Apparently, the safest course of action is to use a
> buffer circuit with any rig and an amp of a diferent
> manufacturer. There are issues of one sort or another
> with Kenwood, Yaesu and Ten-Tec as well.
> 
> All in all, an interesting post, Adam. Much to digest.
> 73, Larry W3UIO
> 
> 
>>Best 73,
>>Adam, VA7OJ/AB4OJ
>>North Vancouver, BC, Canada
>>http://www.qsl.net/ab4oj/
>>Icom FAQ Site:
>>http://www.qsl.net/icom/
> 
> 
> 
> __________________________________________________
> Do you Yahoo!?
> Yahoo! Mail Plus - Powerful. Affordable. Sign up now.
> http://mailplus.yahoo.com
> ----
> Your Moderator: Dick Flanagan W6OLD, icom-owner@mailman.qth.net
> Icom Users Net: Sundays, 1700Z, 14.315 MHz
> Icom FAQ: http://www.qsl.net/icom/