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TOPIC: PIN diode T/R switching

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

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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
73 Rick
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PIN diode T/R switching 14 Jun 2021 00:43 #8

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PIN diode T/R switching 24 Jun 2021 11:36 #9

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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 #10

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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 #11

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 #12

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 #13

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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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PIN diode T/R switching 14 Aug 2021 09:13 #14

I'm a bit late to this particular party but would like to put in my 2 cents.

Pin diode T/R switching can provide significant benefit to both CW and SSB operators and there is no reason to consider the associated parts costly. PIN diodes for use at up to the 100W level are very low cost these days.

Silent fast T/R makes CW operation a delight whereas clacking electromechanical relays significantly detract from enjoyment of the mode. My EE transceiver is an SDR2PRO rather than the DX. I don't need 100W as I have RF Kit LDMOS amps which can be driven fully with between 1-2W. QSK is my favoured way of operating CW as a good QSK system provides on frequency awareness while sending. A great benefit when engaged in conversational CW and your QSO partner wants to break in and most useful when QRM appears on frequency. For QSK I use my Elecraft K3 which has very capable QSK.

My SDR2PRO is not capable of QSK at any speed currently, even 10 wpm. I can reduce Break in delay to 1mS and the relay chatters like crazy but despite the relay changeover RX recovery is way too slow. I am guessing of course but suspect the RX stays quiet until the pipeline is refilled which takes several mS. This issue would need to be addressed for QSK to become a possibility PIN diodes or not. One approach is pipeline retention on PTT to avoid the pipeline refill delay.

For SSB PIN diode T/R provides the opportunity to implement super-vox. What is that? Well the opportunity arises out of the inherent pipeline delay. R/T switching can be invoked as soon as audio reaches the mic which will be several mS before the audio emerges from the pipeline. T/R can be switched whenever the pipeline is empty. The effect is almost like operating duplex on a single frequency making VOX operation lightning fast and silent aiding normal conversation flow.

I very much hope both fast T/R turnaround and PIN diode T/R will figure in the future of EE transceivers.

73 Bob, 5B4AGN
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PIN diode T/R switching (Re: I "kind of agree" and "kind of disagree".) 14 Aug 2021 09:46 #15

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Dear Pavel (VK6NX),
thanks for the inspirational answer. Unfortunately, I'm afraid we don't understand each other. I have no problem to read that my comments are being considered as not acceptable, also it does not need to be camouflaged as "kind of agree". I understand your reaction to be that my suggestion is completely rejectable and you are in favor of an antenna relay because you believe that it is significantly cheaper and that a switch with PIN diodes could cause an increase in price. For the addition of "It has dedicated channels for signal and RF circuits", I can only thank you that, as an engineer with 45 years of experience, I am clear on these issues. In any case, as technicians, we should discard scruples, abandon unnecessary courtesy rituals, and express ourselves directly. By no means am I interested in inducing flamewars myself, and I almost always resist attempts to involve me in similar events.

It might not be out of place to read my other comments related to this issue:
eesdr.com/en/forum-en/software-ss2/7771-warning-ptt-swithing-delay-in-cw

Perhaps this comment will help explain why I must consider the use of an electromechanical relay to T/R switch the antenna in the second decade of the 21st century as a design flaw. Use of a relay is not surprising for the large manufacturers of the Yacomwood triumvirate, their products are developed and manufactured (for the mainstream majority) with maximum profit in mind. For smaller manufacturers, led and owned by hams, however, I would expect a different approach - from hams to hams (because their products being dedicated to advanced, experienced and specialized minority). This is how Elecraft or Ten-Tec work in the USA - by the way, the history of these companies is very enlightening, and if we know their products, it explains a lot. Maybe it's my fault that I put Expert Electronics into this category. Although I could be warned by the fact that the guys from EE know so little about CW - in the BreakIn menu, the Curtis B mode is actually hidden under the “Iambic” label, while the Curtis A mode is labelled as “Type B”. The misleading “BreakIn” label I have already pointed out in the comment mentioned above. Anyway I still believe that EE belongs into this category mainly because most of its customers are hams.

Today, everyone says that CW is his favorite or main mode. In fact, there are quite few of us who can prove it. I belong to them - whoever looks at my profile on QRZ.com, for example, will see. I can offer more than 50 years of experience with various transceivers and amps from several manufacturers. Anybody who is interested can evaluate it. And indeed, the German company RF-Kit (rf-kit.de/) did it, which I managed to bring around to convert their 1.5 kW LDMOS amp RF2K+ from relay T/R switching to PIN diode T/R switching, thus creating a new RF2K-S model. Of course, this is not just the result of my efforts, it required broader user support, but RF-Kit knew how to respond and did it quickly. At present, the RF2K+ (relay switched) is no longer manufactured and only the RF2K-S type is offered (BTW RF2K-S is newly TCI compatible and can be perfectly controlled by SunSDR2 DX!). Of course, the price of this LDMOS PA has not changed and there is no reason to increase it - if the manufacturer does not want to increase the price, he simply will not. I think this example explains the term "by hams to hams" very well.

I would like to be wrong, but I have the impression that Expert Electronics is not interested in the comments of competent customers. I know very little about Expert Electronics, practically only what was published on its website. However, if the development of RF components is done by the same people as those who develop software, I am very sorry, but if EE does not hire an adequate number of technicians, will lose any chance in the market. Of course I strongly believe that EE know what they doing, so the argument
"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"
must be therefore considered as completely odd.

I don't think I belong to a demanding minority making nonsensical demands, I don't even think that my other suggestions would be nonsensical at all (now I'm not talking about T/R switching, but about simple software enhancements that can fundamentally improve the subjective sense of rig quality – eg. chainable E-coder button commands). Typically, these suggestions go unnoticed by the manufacturer, and the fact that they go unnoticed also by users illustrates (at least in my eyes) who the SunSDR2 users are. Here it is worth to mention the too slow bug fixing and the "secret" releases of patch versions of ESDR2 (I found the Update10 of ExpertSDR2 1.3.1 only thanks to a link from a German user on the Telegram network, official website still offers only Update9).
Last Edit: 14 Aug 2021 09:47 by OK1RR. Reason: typos
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