T/R Switch

[W8EJO]

I'm thinking of building a T/R switch.

After doing a Google search with unsatisfying results
I'm wondering if anyone has built (or has a circuit for) a T/R Switch
that will cover 160-10 & handle 500 watts or so?


Terry
W8EJO

[Pete, WA2CWA]

You didn't say tube or solid-state but a QST and Ham Radio Mag. search up on the ARRL web site pulled up a bunch of them.

Also to go BAMA and pull down the B&W 381 and Johnson T/R Switch circuits. Both were designed for 80 to 10 meters, but probably with a little tweaking, you can probably pull it down to 160. I think ER Mag. also had some info over the years and I haven't even looked at the CQ index yet.

Here's the Johnson schematic:

[W3SLK]

Pete said:

Also to go BAMA and pull down the B&W 381 and Johnson T/R Switch circuits. Both were designed for 80 to 10 meters, but probably with a little tweaking, you can probably pull it down to 160.

The Johnson T/R provides a little bit of gain for the receiver on 80-10. I have been using mine on 160 without any ill effects for some time now. If I were going to build one, I would solid state the power supply. Since it supplies a good amount of heat. But I wouldn't worry about using it on 160.

[W8EJO]

Thanks - I should have thought about just copying one of the old commercial units.

[ve6pg]

..i just use 115volt relays,switching werks fb,and other contacts mute the receiver..no rfi/tvi or whatever..tim...sk..

[K1JJ]

Hi Terry,

Were you looking for an electronic T/R switch for CW break-in operation of just a standard mechanical relay system?

For a mechanical system, for antennas, I use any open frame relay that I have available. The ones that use 24V coils and are maybe 2" X 2" square will handle 5KW easily. [10-20A contacts] The trick for getting a 1.1:1 swr thru them is to mount the relay lugs as CLOSE to the chassis SO-239's as possible. Think it out before mounting the relay. If you can keep the path real short, plus route the input and output wires close to the chassis to simulate a 50 ohm line, you can get 1.1:1 on 10M. I even made one for 6M and does FB. You want the relay almost sitting on top of the SO-239's in and out for best results.

Once you build it, put a 50 ohm resistor/dummy on the output and sweep it with an MFJ ant analyzer to see how well you did.  Some guys pay $400 for high class antenna relays on 6M. I've proved to myself that you can do it a lot cheaper idf the layout is tight and short..  $100 DowKey relays are not needed on HF either, tho they are EZ to use.

For the DC switching [not antennas] use any relay you have and make the leads as long as need be. Just put all relay coils in parallel and they will switch together. Or sequence them if need be with a delay, etc.

73,
T

[w3jn]

Do clip leads work OK on 6, Tom?

[K1JJ]

Do clip leads work OK on 6, Tom?

Good question! Yep, nothing better, John.

Planning on building up a 6M linear with them?

[w3jn]

I was planning on using the distributed reactance of clip leads to build a nice 6M amplifier out of a quad of slightly gassy 6LF6s I have kicking around.   Despite a rigorous Smith chart analysis of both the input and output clip lead networks it's not working out too well.  Any tips so I can get in touch with my feminine side on 6M with youse guys?

[WA1GFZ]

I used a P&B 25 amp DPDT with contacts in parallel and it took all the 4CX3000A could deliver. 115 VAC coil works fine with 28 VDC. 

[W8EJO]

Were you looking for an electronic T/R switch for CW break-in operation of just a standard mechanical relay system?

For a mechanical system, for antennas, I use any open frame relay that I have available. The ones that use 24V coils and are maybe 2" X 2" square will handle 5KW easily. [10-20A contacts] The trick for getting a 1.1:1 swr thru them is to mount the relay lugs as CLOSE to the chassis SO-239's as possible. Think it out before mounting the relay. If you can keep the path real short, plus route the input and output wires close to the chassis to simulate a 50 ohm line, you can get 1.1:1 on 10M. I even made one for 6M and does FB. You want the relay almost sitting on top of the SO-239's in and out for best results.

Once you build it, put a 50 ohm resistor/dummy on the output and sweep it with an MFJ ant analyzer to see how well you did. Some guys pay $400 for high class antenna relays on 6M. I've proved to myself that you can do it a lot cheaper idf the layout is tight and short.. $100 DowKey relays are not needed on HF either, tho they are EZ to use.

For the DC switching [not antennas] use any relay you have and make the leads as long as need be. Just put all relay coils in parallel and they will switch together. Or sequence them if need be with a delay, etc.

73,
T

Thanks Tom

I was hoping to avoid ker-chunking relays. I do use VOX & occasional CW so I was hoping for QSK.

I never run over 500-600 watts so the schematic above should work. May need to increase L to handle 160.

Terry
W8EJO

[K1JJ]

Any tips so I can get in touch with my feminine side on 6M with youse guys?

No tips needed, OM. I think you're almost there in the spirit already.  Though, if you paint the front panel of your new 6M linear translucent hot pink, it helps as a reminder.

BTW, Gary/INR built his first of two, HB 5el 6M Yagis yesterday and got it tuned up at 1:1. He temp raised it to 20' and made his first corntact in NH.

Join us and you will have access to SMA, "Six Meters Anonymous", to work out your inner emotional conflicts.

T

[Glenn NY4NC]

I'll be joining you guys on 6m once I get down to my new QTH in North Carolina although I'll have to be a closet operator cauz dem southern boys don't like no yankee 6m feminine ops caw mawn!!