When is a transfer relay not a transfer relay?
Normally, a transfer relay can be considered as a “double change over” device, but not all transfer relays may be manufactured to behave like this… and this can be used to our advantage!
Purchased off eBay http://www.ebay.com.au/itm/300618827064 from “2010bluebook” in China (who has a 100% rating BTW), for USD$80 each including postage.
A basic continuity check revealed that J3 did not connect to J1 in the normally closed (NC) (ie; unpowered) state, as might be expected in a classic transfer relay.
Normally, you might have a transceiver connected to J2, with antenna connected to J4, and a Power Amplifier or pre-amplifier connected between J1 – J3.
A normal transfer relay would then connect the input and output of the amplifier in one state or the other, and this might be a concern.
Not so, with this particular relay from this eBay vendor!
Note these relays have 6 gold-plated fingers as contacts on the centre pin.
Coloured texta was used to mark the findings for easy later reference.
In Archived VK Logger Forum topic, Wayne, ZL2BKC kindly provided the following plots of his ARS-BPR-01N relays.
Above: Insertion Loss
Above: Isolation
By all accounts, these relays offer great isolation and low insertion loss, and as SPDT change-over relays (ie; ignore J3 completely), are ideal for high powered applications up to 23 cm.
One of these is going into a 150W 23cm power amplifier project! 🙂
