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Reviews For: TRS-460 T/R Switch - RX Interface

Category: Antenna Switching, Phasing, Controllers

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Review Summary For : TRS-460 T/R Switch - RX Interface
Reviews: 1MSRP: $127 USD
Description:
TRS-450 TRANSMIT/RECEIVE SWITCH & RX INTERFACE - BUILT & TESTED MODULE ENCASED IN ALUMINUM BOX Product is from Greece and is often available on eBay.com as well as from www.sv1afn.com
Product is in production
More Info: https://www.sv1afn.com/en/products/trs-450-transmit-receive-switch-rx-interface.html
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
0014
KB0US Rating: 2022-01-31
Pretty nifty but . . . Time Owned: 0 to 3 months.
I needed an RX/TX switch to integrate a receive only antenna into the shack along with an RTL-SDR dongle for use as a panadapter.

This also requires an RF splitter to split the receive antenna's signal into a path to the rig and a path into the dongle that are both 50 ohm. Just tying the two receiver inputs together and connecting them to the antenna isn't optimal but that's a longer discussion.

There are lots of these T/R switching devices including some very inexpensive Chinese variants which I haven't tried. I saw the TRS-460 on eBay and I liked that it had both RF sensing as well as an RCA jack for connection to the rig's PTT line.

If you're interested in this unit, make sure you read the web page since this is "the manual"; no other documentation is provided. There's also a schematic on the website that can be downloaded. Note that the two front panel switches are not shown on the schematic.

If you buy the device on eBay and you are in the U.S., make sure you follow the ordering instructions to avoid paying the VAT tax. If you order from the website, I'd contact SV1AFN before you place your order.

1. Delivery from Greece was painless with the entire process taking about 3 weeks.
2. The unit is quite small at approximately 4"X4"X2."
3. The PTT jumper inside is configured for active low which was also how my FTDX10 works. This isn't documented anywhere. As an aside, there are DIN (or whatever) to RCA connectors available on eBay from various sources to simplify connection to the radio should you not wish to buy the individual parts and make your own cable.
4. I like the ON THE AIR sign just because it's cool.

There is a switch on the front panel labeled INJECT DC which puts 12V on the receive antenna's coax when switched on. In my installation, I wanted to use the voltage inserter provided with the receive only antenna (I happen to have a W6LVP) because that seemed safer and if the TRS-460 failed, I'd still have a functional receive antenna by grabbing the wall wart provided with the W6LVP loop. Also, the splitter I have for splitting the signal between the SDR dongle and the FT-DX10 was not "dc passing" (i.e., it has inductors to ground) and would just short out the TRS-460's 12V "injector" and blow its fuse. Also, even if I purchased a "dc passing" splitter, I might have also applied 12V to the RTL-SDR dongle which didn't seem like a good idea either. Bottom line here is that applying the needed 12V to the W6LVP antenna was better done using the supplied injector rather than trying to eliminate that device and applying it with the TRS-460 through the splitter.

The message here is that figuring out the antenna path is not as easy as it might seem!

However, I DID want the TRS-460 to supply the 12V to the W6LVP's voltage injector (which supplies 12V to the amplifier that's part of the antenna system) because the TRS-460 only supplies 12V during receive causing the receive antenna to be turned off during transmit which seemed like a very good safety feature so I didn't blow out the amplifier in the W6LVP loop antenna.

What I wound up doing was cutting out the INJECT DC switch (I tried desoldering but got concerned I would damage the board) and ran a cable out the empty hole to the w6LVP voltage inserter from Jumper 2-1 on the schematic of the TRS-460. I could have also, of course, drilled a hole in the rear panel and installed a connector. However, I really didn't like the switch being there since there was always a chance of accidentally throwing it and damaging the TRS-460. By the way, the switch is not shown on the schematic and is in parallel with Jumper 2 pins 1 and pin 2.

In my view, the INJECT DC switch should be a connector and not a switch with the 12V enabled by the internal jumper which, I suspect, is how it was originally intended.

Like other similar units I looked at, the TRS-460 connects the main antenna (J1) to the radio (J4 XCVR) when it's turned off allowing you to use the transmitting antenna for receive as well. Unfortunately, the PWR switch turns off the 12V entirely so the ON THE AIR light doesn't work. Pity.

There is a 350mA fuse but it's a surface mount device so if you blow it, it's going to be a tad tricky to replace.

As far as customer service, I sent SV1AFN an email with a question and did not receive a reply.

i rated the product as "good" because it does everything it's supposed to. I think it would be better with replacing the INJECT DC switch with a connector with the decision about whether to put voltage on this connector made by a jumper internal to the device to avoid the possibility of blowing the internal SMD fuse. Also, the PWR switch should be labeled ANTENNA in the "off" position and RECEIVER in the "on" position with this switch controlling only the 12V to relays K1 and K2 allowing the ON THE AIR led to work in both modes.