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TOPIC: PIN diode T/R switching discussion

PIN diode T/R switching 02 Apr 2021 14:02 #1

  • OK1RR
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Why nearly every modern radio employs a mechanical relay for T/R switching? I believe that a radio equipped with half of doyen processors must not make the same noise as the grandma's sewing machine while operated on CW! I see only one reason - the manufacturers simply ignoring CW as a mode. This is an unacceptable fact :stars:
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PIN diode T/R switching 09 Apr 2021 20:35 #2

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Great idea!
I know of only one vendor, Elecraft, who uses PIN Diodes for their Transceivers and Linear Amplifiers. Are there others?
CW certainly is a dead mode in the USA, but may still be a REQUIREMENT in other countries (Japan for example)?
72/73 de Ken N9VV
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PIN diode T/R switching 10 Apr 2021 07:59 #3

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I use a 1 kW LDMOS power amplifier with diode switching: Gemini HF-1K (www.linamp.co.uk/gemini_HF.html). A ufb PA!
Unfortunately, Expert does not (yet) have a transceiver with fast diode switching in its sales program.
Let's see what the future holds.
A SunSDR Pro with diode switching would be just right, because modern LDMOS PAs only require 10 watts of input power for 1 kW out.

vy 73, Hubert
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PIN diode T/R switching 11 Apr 2021 20:09 #4

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CW is a dead mode in the USA? Not by a long stretch. Been licensed since 1976 and CW is more active now than ever, the difference being the operators using CW choose to (and enjoy it).

PIN diode switching would be great, I wish more would use it. Ten-Tec used it as well, but they are not really around any more. Operating full break-in without it is not enjoyable for sure.

Doug
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PIN diode T/R switching 11 Apr 2021 20:48 #5

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Ken, you should say this to the CWops staff! They reply would be very interesting! BTW expeditions getting most QSO on CW (with very few exceptions), also CW parts of contests have more participants than Phone.
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PIN diode T/R switching 11 Apr 2021 20:55 #6

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Yet another full legal limit (~1.5 kW RF out) LDMOS amp with PIN diode T/R switching (thus full QSK) is produced by RF Kits in Germany rf-kit.de/ Also offered by DX Engineering.
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PIN diode T/R switching 11 Apr 2021 21:23 #7

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Pin diode would be nice-
I like CW but don't use it as much as couple other modes

I will comment that at least the 2DX model isn't as noisy as a few other rigs that still use relays as well-
But it isn't as quiet as my Acom1000 is even though its not an LDMOS
Please do not email me and ask for help I no longer will be part of this, If I could delete /remove my profile I would do so.
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PIN diode T/R switching 15 Apr 2021 19:40 #8

This is a great wish-list item Martin- I would purchase a SunSDR2-DX today if it had silent, PIN Diode T/R switching. There is a real opportunity for a company to take CW operators business right now, as Elecraft can't seem to get the K4 released, and there aren't many other good CW choices out there. As a 95% CW operator, I would like to know if the SunSDR2-DX is a good CW rig other than the relay based T/R? Does the software have basic features like auto-spot? I may still consider trying this rig- I'll just have to put it in the closet behind the shack so that I don't have to hear that noisy relay.
73-
Jason AC7JW
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PIN diode T/R switching 16 Apr 2021 04:31 #9

I share this frustration Martin. These young engineers at Expert Electronics are extremely bright and talented, but they must not be CW ops. With the "failure to launch" of the K4, this is a perfect time for an aggressive young company like EE to come in with a good solid state (PIN diode) T/R switch and win the loyalty of the CW crowd, which as you suggest, is much larger than people think. There seems to be and especially committed CW crowd in Russia and eastern Europe, so Expert could certainly have an immediate fan base.
If the SunSDR2DX had QSK with PIN diodes, I'd buy one right now! That being said, I'm still considering it. Outside of the noisy, clacking "sewing machine" relay, how does the SunSDR2DX perform on CW? Does the software have CW auto-spot? Is the side tone good? I'd love to hear your thoughts on this.

73-
Jason AC7JW
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PIN diode T/R switching 14 Jun 2021 00:43 #10

Thank you
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PIN diode T/R switching 24 Jun 2021 11:36 #11

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Any news about the external PIN diode T/R switch? Can we count on this? Will SunSDR2 DX became once a perfect CW radio? Please keep us informed! Many thanks in advance!
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PIN diode T/R switching 25 Jun 2021 06:34 #12

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It's in our plans, but not for the near future.
There are several other ideas, which we need to develop and implement first and then move to the external PIN diode switch.
I'd say not sooner than the end of the next year.
Роман, Roman
Expert Electronics
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PIN diode T/R switching 21 Jul 2021 10:37 #13

It is a shame that CW always has to stand in the back. Flexradio drives the same policy ... That means, I have to wait a long time. I don't want to have another "rattle box" in the shack. 73! Uwe - DK3WW
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PIN diode T/R switching 13 Aug 2021 22:09 #14

I agree with OK1RR- if you add PIN Diode switching, you can capture even more of the still-strong CW market out there because other than the relay noise, the SunSDRDX2 is a terrific CW Rig. I've been running mine for several weeks using CW exclusively, and I really enjoy many of the features. It will be fun to see what comes in the next EESDR3 release. Keep up the great work!
73- AC7JW
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PIN diode T/R switching 13 Aug 2021 23:04 #15

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I "kind of agree" and "kind of disagree".

However, my strong believe is that PIN diodes for T/R need to be looked from all perspectives, not only from perspective "because it is innovative". And, additionally, the feedback (which is coming with PIN diodes embedded), has to be understood.

Definitely, why everyone is still using relays? Obviously, because of two reasons: 1. It is much cheaper and 2. It has dedicated channels for signal and RF circuits.

As for 1: while pushing EE towards PIN diodes, make sure you understand that the price of DX-PIN will immedeately bump up 300+ bucks. And EE transceivers are very good in price (personally I really prefer it stays this way).

As for 2: we all know that good designed Mux-Demux is costly. In time/money it means a) programmers will spend valuable time to design and embed PIN diodes, and b) it means another bump up in price (due to conversion from time to money) - and this bump, believe me, would be twice as price for physical PIN diodes.

Do not interpret me wrong - CW is my main mode. I would be excited see any improvements in this more in EE products. But am I ready to pay 4K instead of 3K for this enhancement? Perhaps not.

So, the global answer, why PIN diodes are still not there? On a same reason, why Telnet and RS-232 still in use. Just small difference - relays are still not obsolete, when Telnet and RS-232 are. And I personally prefer, per say, EE first fix their current "Telnets" and "RS-232s" and only then look at relays.
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