Quieting TX/RX relay

N4XD
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Quieting TX/RX relay

Postby N4XD » Mon Jan 24, 2022 2:04 pm

Re TX/RX relay.

Is it the EC2-12-NU relay on the xmit filter board? The relay in the upper right side of the schematic?

Anyone done any mods to quiet this relay? To me seems unusual, in this day and age, to have a moderately loud mechanical relay for this function. Perhaps something like reed relays or pin diode switching would be much nicer (and quieter). Anyone thoughts?

Thanks

Ron
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Re: Quieting TX/RX relay

Postby W2PA » Mon Jan 24, 2022 5:04 pm

Some of us have thought about this for a while, Ron. I'd love to have QSK be silent like it is on the two amplifiers I have that use PIN diodes. In the 8000DLE there are two relays involved, one is an EE2-12NU-L (receive path) and the other is 277-4907-ND (transmit path). They are both on the PS and Directional Coupler board. It should be straightforward to replace them with much quieter relays I've found at (for example) Mouser. The QSK in my old FT-1000D uses a combination of diodes and a relay (reed relay I presume) that is so quiet that I never knew it was there until I looked at the schematic. So it's certainly possible but I haven't yet taken the plunge to do it.
73,
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Re: Quieting TX/RX relay

Postby w-u-2-o » Mon Jan 24, 2022 6:22 pm

But it's still going to be a high power relay, which means relay speed and relay lifetime.

It's unfortunately that with all of the great hobby modules for solid state power amp's currently available, nobody has designed and produced a diode T/R switch module. They are somewhat non-trivial, particularly for QRO power levels. And they require a source of high voltage. IIRC it's 270VDC in the Elecraft designs! So it would be important for the module to include an onboard HV power supply.
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Re: Quieting TX/RX relay

Postby oe3ide » Mon Jan 24, 2022 6:25 pm

w-u-2-o wrote:But it's still going to be a high power relay, which means relay speed and relay lifetime.

It's unfortunately that with all of the great hobby modules for solid state power amp's currently available, nobody has designed and produced a diode T/R switch module. They are somewhat non-trivial, particularly for QRO power levels. And they require a source of high voltage. IIRC it's 270VDC in the Elecraft designs! So it would be important for the module to include an onboard HV power supply.


Except LinearAmp with the Gemini HF-1K. But this design has also some drawbacks (ie. spurious)

73 Ernst
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Re: Quieting TX/RX relay

Postby dl4zbg » Mon Jan 24, 2022 6:36 pm

One relay is not enough....
4 years ago I had a mail exchange with Kjell LA2NI who intended to create a Pin Diode T/R switch.....
In case of the 7000DLE you have also to consider changing/dealing with RL17,RL19 and RL36 for RX2 grounding.

https://www.youtube.com/watch?v=QDYfEBY9NM4


73

Volker

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Re: Quieting TX/RX relay

Postby N4XD » Tue Feb 01, 2022 12:06 am

All,

Thanks for the replies.

Doesn't need to be high power since only switching power out of the 7000.

I did find one pin diode switch but large circuit board. I think too big to fit in the 7000 dle case. Maybe pin diodes aren't the way to go. Maybe jennings (or similar) vacuum relays for the 100W part and reed relays for the other stuff?

Ron
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Re: Quieting TX/RX relay

Postby w-u-2-o » Tue Feb 01, 2022 2:40 am

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Re: Quieting TX/RX relay

Postby w9ac » Sun Mar 06, 2022 9:09 pm

Ron,

I replaced the T/R relay in my 7000DLE with a quiet Aromat RSD-12V RF reed relay. It was also produced under the Panasonic/Matsushita brand.

The relay is attached to the PC board with small pillows of silicone RTV that mechanically isolate the relay from the PC board. isolation is further reduced by using small loops of fine-stranded silicone robotics wire between the relay pins and the PC board, The wire is formed into small loops to minimize any mechanical transmission. After the mod, T/R transitions are completely silent

But for CW ops, that's just half the solution. One of the PureSignal relays is hardwired in parallel with the T/R relay. For me the complete solution meant building a custom microcontroller board that senses CW activity, then opens up two PureSignal relay coils during a CW transmission. Installation can be completely reversed at a later time without leaving any modification trauma.

The schematic and code can be downloaded from my QRZ page. The PC board can be ordered direct from OshPark:

https://oshpark.com/shared_projects/KEAYgY9b

K1 is Panasonic AQW21 (or equivalent dual MOSFET SSR) http://www.farnell.com/datasheets/88983.pdf
R1-R3 = 220 ohm ¼ watt
D1, D2, D4 = 3 mm yellow LED
D3 = 1N4001 (or equivalent)
C1, C2 = 0.001 uF film

The Arduino board has much more switching capacity than required. Today, I would design it with a smaller device like the Adafruit Trinket M0. It runs on the same code.

Paul, W9AC
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Re: Quieting TX/RX relay

Postby dl4zbg » Sun Mar 13, 2022 12:39 pm

Paul,

do you have photos showing the new relay and the mod for RL19 and 36 for the 7000 DLE?
I think it will be a good ideal to modify Thetis in order to activate an OC output in CW mode or something similar.

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Re: Quieting TX/RX relay

Postby w9ac » Fri May 27, 2022 12:46 pm

dl4zbg wrote:Paul,

do you have photos showing the new relay and the mod for RL19 and 36 for the 7000 DLE?
I think it will be a good ideal to modify Thetis in order to activate an OC output in CW mode or something similar.

Volker DL4ZBG

Sorry for the very late reply...

The only photos I have are shown on my QRZ page but unfortunately, none of those show changes to the PA board.

By the way, the PureSignal relays to mute in the 7000DLE in CW mode are RL17 and RL19. The PC board on my OshPark page shows them as K17 and K19.

It would be great if the Thetis OC table would eventually allow a user to select OC outputs based on a choice of mode or band of operation. That way, the OCs would automatically deactivate the PS relays when in CW mode, thus eliminating the Arduino microcontroller. It stills requires lifting one side of the relay coils from the PC board to insert the OC.

Paul, W9AC
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Re: Quieting TX/RX relay

Postby N4XD » Fri May 27, 2022 1:17 pm

Paul I do plan to make the changes per your info. I am portable in NM using an Elecraft K3 as the rig. Spoiled by its soundless keying. No idea why Apache labs didn't go the pin diode route. Not only noisy but, using the internal keyer, I found needed large delays to keeps from hot keying. Not at all good for contesting.

Ron
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Re: Quieting TX/RX relay

Postby w9ac » Fri May 27, 2022 1:32 pm

N4XD wrote:Paul I do plan to make the changes per your info. I am portable in NM using an Elecraft K3 as the rig. Spoiled by its soundless keying. No idea why Apache labs didn't go the pin diode route. Not only noisy but, using the internal keyer, I found needed large delays to keeps from hot keying. Not at all good for contesting.

Ron
N4XD

At the very least, the design should have separated one of the PS relays from the T/R relay. As designed, the coils are connected in parallel. Second, the PS coils should be inhibited in CW mode. Of course, that requires input and control from Thetis.

I'm OK with a quiet reed relay for the T/R function. It's not so easy to accomplish in mass production. The relay requires adequate isolation from everything around it including the PC board and wiring.

To do PIN switching right requires a more complex design with RF chokes and a layout with good isolation. It also means back-biasing the receive diodes with several hundred volts to protect the receiver when accidentally transmitting into an infinite SWR. Fast-acting SWR protection circuitry isn't enough. Elecraft's PIN design in the K3 and K4 is quite good. I've not seen any reports of PIN diode failure.

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Re: Quieting TX/RX relay

Postby w-u-2-o » Fri May 27, 2022 1:41 pm

N4XD wrote:Paul I do plan to make the changes per your info. I am portable in NM using an Elecraft K3 as the rig. Spoiled by its soundless keying. No idea why Apache labs didn't go the pin diode route. Not only noisy but, using the internal keyer, I found needed large delays to keeps from hot keying. Not at all good for contesting.

Ron
N4XD

If you have a 200D, 7000 or 8000 you can use the true QSK mode to solve that problem.
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Re: Quieting TX/RX relay

Postby N4XD » Fri May 27, 2022 4:06 pm

I do have a 7000 blue face so yes, could do qsk. But the relay racket and wear and tear on the relays is not something I want to listen to nor do. But I'll explore that option more once I get back to NC. Presently I use a winkeyer which provides a ptt signal. Using that to key the rig has eliminated the hot keying and long delay.

Thanks

Ron
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Re: Quieting TX/RX relay

Postby W4WMT » Fri May 27, 2022 8:09 pm

w9ac wrote:By the way, the PureSignal relays to mute in the 7000DLE in CW mode are RL17 and RL19.


Studying the prints again, I see that the RY17 coil is tied to an 8-bit shift register (poor man's SPI). So we should be able to inhibit that relay (when in CW mode) with some relatively straightforward coding in Thetis. But to tie the RY19 coil into an OC output, I think, will require some buffering unless you see some way to do it directly. Then both relays (RY17 & RY19) can be inhibited while in CW mode by a little coding in VS.

73,
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Re: Quieting TX/RX relay

Postby w9ac » Fri May 27, 2022 9:57 pm

RL17 and RL19 are both driven by identical but separate 8-bit shift registers. Register U5 controls T/R relay K5 and RL19, and U5 must remain connected to K5 to perform the T/R function.

The OC driver is a ULN2003AD Darlington device. Each output channel is rated for 500 mA of current** so it's easily capable of switching RL19 to circuit ground with no additional buffering needed.

Paul, W9AC

** the device is capable of switching 500 mA but I doubt the microscopic PC board traces will safely handle that much current.
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Re: Quieting TX/RX relay

Postby W4WMT » Fri May 27, 2022 10:35 pm

w9ac wrote:RL17 and RL19 are both driven by identical but separate 8-bit shift registers. Register U5 controls T/R relay K5 and RL19, and U5 must remain connected to K5 to perform the T/R function.


That's even better then!
Move RL19 over to the unused pin on U10 (which already controls RL17) and inhibit both relays with SPI instead of OC?

73
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Re: Quieting TX/RX relay

Postby w9ac » Sat May 28, 2022 12:02 am

W4WMT wrote:
w9ac wrote:RL17 and RL19 are both driven by identical but separate 8-bit shift registers. Register U5 controls T/R relay K5 and RL19, and U5 must remain connected to K5 to perform the T/R function.

That's even better then!
Move RL19 over to the unused pin on U10 (which already controls RL17) and inhibit both relays with SPI instead of OC?

73

Not sure how that would work since RL17 and RL19 are controlled differently. RL17 is in series with RL19. RL17 is closest to the Orion Rx1 input while RL19 is connected to the Rx1 BP filters.

RL17 switches to an external PS RF input on the rear panel when "Rx Bypass on Tx" is selected in Thetis. RL19 works like a T/R switch with RF from the Rx1 bandpass filters selected during Rx and the Internal PS RF input on Tx. That's why it's wired in parallel with K5, the master T/R relay.

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Re: Quieting TX/RX relay

Postby W4WMT » Sat May 28, 2022 12:47 am

w9ac wrote:Not sure how that would work since RL17 and RL19 are controlled differently.

Right, it wouldn't work i.e. not without reprogramming the SPI commands sent to the relevant shift registers. But after thinking about this for an hour, I now remember the terrible trouble Phil and Rick were having with the SPI during protocol-2 rollout (for the 7000 I think). So I like your approach best, I think. After all, we're not trying to control RL17 & RL19 per se, we're just wanting to preclude their use when the rig is in CW mode. Can't we just use your circuit, but drive the OptoMOS relays with one of the OC outputs instead of using a Nano? Then it's just a little code to float the OC output when CWL or CWU is selected in the Thetis console. No?

73
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Re: Quieting TX/RX relay

Postby w9ac » Sat May 28, 2022 2:23 am

W4WMT wrote:
w9ac wrote:Not sure how that would work since RL17 and RL19 are controlled differently.

Right, it wouldn't work i.e. not without reprogramming the SPI commands sent to the relevant shift registers. But after thinking about this for an hour, I now remember the terrible trouble Phil and Rick were having with the SPI during protocol-2 rollout (for the 7000 I think). So I like your approach best, I think. After all, we're not trying to control RL17 & RL19 per se, we're just wanting to preclude their use when the rig is in CW mode. Can't we just use your circuit, but drive the OptoMOS relays with one of the OC outputs instead of using a Nano? Then it's just a little code to float the OC output when CWL or CWU is selected in the Thetis console. No?

73

Yep. The only reason for the Nano microcontroller is to sense the input key dit and dah lines and hold off on the PS relays for 500 ms just to unnecessarily have them engage and disengage with every keyed element. I sensed the key line this way as there was no other way to tap a circuit point on the Orion board to annunciate CW mode.

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Re: Quieting TX/RX relay

Postby W4WMT » Sat May 28, 2022 10:32 am

w9ac wrote:Yep. The only reason for the Nano microcontroller is to sense the input key dit and dah lines and hold off on the PS relays for 500 ms just to unnecessarily have them engage and disengage with every keyed element. I sensed the key line this way as there was no other way to tap a circuit point on the Orion board to annunciate CW mode.

So, if we wanted to accomplish the same thing using an OC output instead, do you think it would be okay to use one of the normally closed (Form B) OptoMOS relays? That way we would only sink the connected OC output when CWL or CWU is selected on the Thetis console. And do you think it would be better to use a hard coded OC output, or make it user selectable from the Setup UI?

73
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Re: Quieting TX/RX relay

Postby w9ac » Sat May 28, 2022 11:24 am

W4WMT wrote:
w9ac wrote:Yep. The only reason for the Nano microcontroller is to sense the input key dit and dah lines and hold off on the PS relays for 500 ms just to unnecessarily have them engage and disengage with every keyed element. I sensed the key line this way as there was no other way to tap a circuit point on the Orion board to annunciate CW mode.

So, if we wanted to accomplish the same thing using an OC output instead, do you think it would be okay to use one of the normally closed (Form B) OptoMOS relays? That way we would only sink the connected OC output when CWL or CWU is selected on the Thetis console. And do you think it would be better to use a hard coded OC output, or make it user selectable from the Setup UI?

73

Form B should work fine. There's essentially no change in spec from Form A apart from the inverted logic used.

I don't think it matters if the OC is hard-coded or user selectable in Thetis. I would probably want it hard-coded as there's really no need to deactivate the OC function.

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Re: Quieting TX/RX relay

Postby w-u-2-o » Sat May 28, 2022 11:27 am

Isn't this all a lot of effort when you can just switch to QSK and be done with it?
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Re: Quieting TX/RX relay

Postby W4WMT » Sat May 28, 2022 12:20 pm

w-u-2-o wrote:Isn't this all a lot of effort when you can just switch to QSK and be done with it?

That's what we're talking about.
Inhibiting RL17 & RL19 while in CW (to minimize relay noise during QSK).
73
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Re: Quieting TX/RX relay

Postby w9ac » Sat May 28, 2022 12:30 pm

W4WMT wrote:
w-u-2-o wrote:Isn't this all a lot of effort when you can just switch to QSK and be done with it?

That's what we're talking about.
Inhibiting RL17 & RL19 while in CW (to minimize relay noise during QSK).
73

And, replacing the T/R relay. Replacing the T/R relay with an RF reed relay allows dialing down key-up/down delays to zero without RF hot-switching. The end result is complete silence during keying and incredibly fast QSK switching times, compatible with PIN diode or vaccum relay-switched amplifiers.

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Re: Quieting TX/RX relay

Postby w-u-2-o » Sat May 28, 2022 2:13 pm

Please forgive my ignorance, gents. I'm not a CW operator, nor can I hear what my 8000 is doing since it is located in a rack two floors beneath my operating location even when I pretend to be one!
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Re: Quieting TX/RX relay

Postby W4WMT » Sat May 28, 2022 2:26 pm

w-u-2-o wrote:Please forgive my ignorance, gents. I'm not a CW operator, nor can I hear what my 8000 is doing since it is located in a rack two floors beneath my operating location even when I pretend to be one!


That's a pretty good way to solve the problem actually.
Just move the SDR hardware out of earshot, and be done with it :-)
73!

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