Re: Wanted Tohtsu CX600NC relay
By having the common port pointing the opposite
way from the other two, the CX520D saves
a lot of space inside a preamp box. I wish there was a wider
choice of relays with that connector layout, and at a similar
price point (which rules out the big, expensive EME relays) but
I have never found even one alternative.
However, the problems with poor isolation and
poor power handling are surprising. I used the same CX520D in
the 70cm EME preamp for many years, handling 1kW CW and
connected directly to the GaAsFET preamp, all with no damage. So
does the performance really fall over a cliff between 432MHz and
A possible explanation for poor isolation is that
there have been at least two versions of that relay, sold under
the same model number. In the modern ones, the isolated contacts
are grounded onto gold-plated contacts that are screwed into the
body. The older ones relied on grounding onto the body itself,
which is a poorer contact and also less reliable... bearing in
mind that the relay will be operated tens or hundreds of
thousands of times, but preamp only has to be unlucky once.
Yet another thought is about the settings of the
moving arms and the actuator plungers. These settings are quite
critical to achieve the correct contact pressures, and the
TohTsu relays aren't exactly built like Swiss watches.
As I said, I do wish there were other relays with
that highly practical port layout and at a similar price point.
73 from Ian GM3SEK
On 09/09/2020 13:29, Colin Ranson wrote: