Here’s yet another approach to solving an issues with the hard to find LZN4 Omron relay on the AVR Board in Kenwood TS-830S transceiver /part # S51-4401-05/.
It’s a 4PDT relay with 12VDC coil, switching various voltages. After few decades and frequent transmit/receive actions, the contacts of this relay become intermittent, resulting in poor receive and reduced power of the transceiver.
After intensive searching of a substitute relay and no luck, I’ve decided to go another way — to make a module that will functions the same, but put together from ready made elements: two DPDT relays, pins, jumpers and custom made printed circuit board.
I’ve examined the stock of relays of a local supplier, and picked the Takamisawa/Fujitsu small signal relays – the NA-12W-K. They are actually really good relays – bifurcated AgPd /or Silver-Palladium/ contacts, capable of 2A switching, very low operating current… The only drawback of these is their polarized coils, i.e. the coil has a “+” and a “-“, which led to a little bit complicating the PCB.
The original:
And the substitute:
The jumpers are added for interchanging the “+” and “-“, just in case if this module is used in another device with different PCB routing of the + and – tracks.
Bench test:
Here’s the result:
And installed:
The space is really tight!
After successful use of the module, but with some misunderstanding about how to switch + and -, depending on the device’s PCB, I decided to make new and simple version of the module. I used high quality relays with non polarized coils and pretty common footprint.
Well, the new module does not look as fancy as the previous, but it’s reliable and universal.
And the simplified version:
Non polarized coil relays, the module will work in various devices, regardless of PCB routing.
Recently /Jan 2018/ tried the PCB service of the www.allpcb.com — sent them the Gerber files and they took care of production.
The result is excellent, the shipping was fast and the price is reasonable.
