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

[W3UIO]

--- 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/


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