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Author Topic: List of radios with silent QSK  (Read 1304 times)

G4IKZ

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List of radios with silent QSK
« on: August 10, 2021, 07:27:43 PM »

Not ready to buy yet but looking at potential replacements for my K3. That has great QSK with silent solid-state T/R switching throughout. And silent solid-state will both be 'must have' in any replacement.  I can see that this topic gets much discussion so I am curious to know if there is a regularly-updated list of radios (new and old) that have this, along with details of any quirks or bugs in their operation.

- Nick
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K6SDW

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Re: List of radios with silent QSK
« Reply #1 on: August 10, 2021, 07:57:04 PM »

Great question Nick, well my IC7300 goes clack clack so I run delayed QSK. My IC746Pro was much better CW rig than the 7300.

I've had 2 Ten Tec rigs over the years and, IMO, and best QSK in the business. My Elecraft K2 was good, not great, but FB cw rig, but crap on SSB. KX3 also nice CW rig as well.

GL/73
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W6UXB

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Re: List of radios with silent QSK
« Reply #2 on: August 10, 2021, 08:02:02 PM »

You should check out the RGO ONE from Bulgaria, a quick search will come up with a lot of info, a modern Ten Tec clone, built for CW operators especially, 73 Geoff
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K0UA

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Re: List of radios with silent QSK
« Reply #3 on: August 10, 2021, 08:08:47 PM »

Icom 7610 if you choose the Mosfet keying instead of the relay keying is silent.
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73  James K0UA

G4AON

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Re: List of radios with silent QSK
« Reply #4 on: August 10, 2021, 11:45:08 PM »

Sold my K3, (which has the later KSYN3A synths) and expecting delivery of a K4D next month. While expensive and with a long delivery time, the K4 is stated to be capable of QSK to 50 wpm. The K3S synths (KSYN3A) give smoother QSK than the original K3 synths, but I’m not sure what the top speed is.

If you check the reviews, you will find some modern transceivers are too slow to operate QSK faster than around 20 wpm.

I am not sure if the above speeds relate to hearing between dots, or between characters. In practice, hearing between characters is generally sufficient to interrupt your sending.

73 Dave
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W9AC

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Re: List of radios with silent QSK
« Reply #5 on: August 11, 2021, 05:50:09 AM »

I presently own an Icom 7610 and RGO ONE.  Both have very good CW QSK and no "dit shortening" nor other keying anomalies. 

The 7610's T/R switching is nearly silent in MOSFET mode but the RGO ONE is completely silent like the K3.  The RGO ONE is a 50W HF-only transceiver. 

I no longer own a Flex 6700 but it had excellent QSK performance with its PIN diode T/R.  The newer generation Flex radios should be similar. 

I suspect the Elecraft K4 will also be silent with PIN diode T/R switching.  The K4D version and IC-7610 have very similar performance and operating features; their receiver architectures are nearly identical.  However, one can almost purchase two 7610s for the price of a K4D with ATU, especially during 7610 sales events. 

Paul, W9AC 

« Last Edit: August 11, 2021, 06:06:16 AM by W9AC »
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KM1H

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Re: List of radios with silent QSK
« Reply #6 on: August 11, 2021, 10:05:31 AM »

Well, backing up a several decades I cant hear my TS-940 or 950SD on CW VOX QSK. Neither can I hear the equally elderly LK-500ZC (1500W capable) that uses a Jennings vacuum relay.

Never had a hot switching issue or shorted finals even in very serious contesting over a decade.

No silly trouble prone antenna tuners used either, the amp does that tuning into VSWR's some would cringe at.....since 1986.   ;D

KISS

Carl
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G4IKZ

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Re: List of radios with silent QSK
« Reply #7 on: August 11, 2021, 11:02:32 AM »

As noted in the original post my goal at this stage is to identify potential K3 replacements. And in the absence of replies about a published list I suspect my best approach is just to look more closely at those radios towards the top end of the Sherwood table. But if it’s useful to anyone else to have a more comprehensive list I’m quite happy to append one to my original post at the top of this thread. (That would save other people from having to read the entire thread). However I wouldn’t have time to research that or ‘look at’ any suggestions so it would depend on those who already know the other radios sharing what they know.

To keep it simple I’d ideally need a clear statement about whether a given radio can do all of its T/R switching (and not just the antenna changeover) in solid-state technology ‑ rather than vague comments like ‘the ABC might do it’ or ‘my XYZ was a nice CW radio.’ If you’d like to have a list or add a radio to the list just add a post to this thread with the above information. But to save me having to read long ‘reviews’ or off-topic essays about favourite CW rigs please put any such information in the first couple of lines.
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K0UA

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Re: List of radios with silent QSK
« Reply #8 on: August 11, 2021, 11:20:45 AM »

OK, let me be clear.  The Icom Ic-7610 is NOT nearly silent, it is TOTALLY silent switchover in CW full break in mode. It uses solid state switching when the MOSFET mode of break in is selected. I don't know how to make it any clearer than that .
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73  James K0UA

G4IKZ

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Re: List of radios with silent QSK
« Reply #9 on: August 11, 2021, 11:37:44 AM »

That's clear enough for me James! But I can no longer see the 'Modify' option that I used to edit my original post. So unless anyone can tell me how to do that it looks like my offer to maintain a list will have to wait. But thanks to all for your replies.

- Nick.
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K0UA

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Re: List of radios with silent QSK
« Reply #10 on: August 11, 2021, 11:59:39 AM »

And as mentioned by others, the Ic-7300 DOES NOT have a silent full break in mode is is very annoying (even with the plastitac modification) to operate on full break in. Too annoying for me to operate that way. I guess they have to cut corners somewhere on the difference between a $1000 rig and a $3000 rig. And that was one of them. Don't get me wrong, I love my 7300's but they are not "superb" CW rigs. They are "get you by, ok," CW rigs.
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73  James K0UA

W9AC

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Re: List of radios with silent QSK
« Reply #11 on: August 11, 2021, 12:17:49 PM »

OK, let me be clear.  The Icom Ic-7610 is NOT nearly silent, it is TOTALLY silent switchover in CW full break in mode. It uses solid state switching when the MOSFET mode of break in is selected. I don't know how to make it any clearer than that .

At the risk of muddying the water, my IC-7610 is nearly silent in the MOSFET switching mode.  I just tried it and I do need to get my ear within a few inches of the cabinet to hear the T/R relay, but it can be heard.  Certainly it's quiet enough that some might say it's totally silent.

The MOSFET being discussed is not the transceiver's T/R mechanism -- it's used for the amp SEND key line and is noted as such in the menu.  When the MOSFET is deselected in the menu, a reed relay is used for amp keying.  That said, the 7610 still uses a relay for T/R switching regardless of the menu setting -- albeit a very, very quiet relay.

A PC board can transmit mechanical sound from a relay armature much the same way a sound board is used to amplify the strings of a violin or piano.  And, because it is a relay and insertion of the relay onto the PC board may vary from unit-to-unit during production, some 7610's may be slightly louder or quieter than the next.

Paul, W9AC
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K0UA

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Re: List of radios with silent QSK
« Reply #12 on: August 11, 2021, 12:46:28 PM »

OK, let me be clear.  The Icom Ic-7610 is NOT nearly silent, it is TOTALLY silent switchover in CW full break in mode. It uses solid state switching when the MOSFET mode of break in is selected. I don't know how to make it any clearer than that .

At the risk of muddying the water, my IC-7610 is nearly silent in the MOSFET switching mode.  I just tried it and I do need to get my ear within a few inches of the cabinet to hear the T/R relay, but it can be heard.  Certainly it's quiet enough that some might say it's totally silent.

The MOSFET being discussed is not the transceiver's T/R mechanism -- it's used for the amp SEND key line and is noted as such in the menu.  When the MOSFET is deselected in the menu, a reed relay is used for amp keying.  That said, the 7610 still uses a relay for T/R switching regardless of the menu setting -- albeit a very, very quiet relay.

A PC board can transmit mechanical sound from a relay armature much the same way a sound board is used to amplify the strings of a violin or piano.  And, because it is a relay and insertion of the relay onto the PC board may vary from unit-to-unit during production, some 7610's may be slightly louder or quieter than the next.

Paul, W9AC

I did fire a lot of firearms when I was younger without hearing protection, but honestly I listened intently and could not hear any click of any kind.
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73  James K0UA

G4AON

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Re: List of radios with silent QSK
« Reply #13 on: August 12, 2021, 12:00:51 AM »

QSK, or “full break-in”, is more than whether antenna and linear keying relays are quiet. The bigger issue is your side tone sounding like a station sending on the band without being accompanied by audible thumps or other extraneous artefacts. In addition, the radio needs to switch fast enough to hear a station between characters, ideally between dots, to more than 20 wpm.

SDR type technology doesn’t readily switch quickly due to inherent latency in the processing of the data stream. Another complication is synthesiser settling time if you operate split frequencies or use RIT. Add in the fact that few amateurs use Morse and even fewer operate moderately fast Morse with QSK, you will see why the ability to cleanly and silently operate QSK is well down the list of design priorities of most manufacturers.

Sadly, QSK smoothness and speed is rarely mentioned in reviews and is not included in the list by Rob Sherwood. A few years ago Amtor switching times were included in some reviews, these days very few of us use Amtor modems. My IC-7300 works well on Amtor with a KAM Plus modem, as does a K3 and a Kenwood TS-480sat. Amtor requires a switching time of around 20 mS or less, although it is not quite the same as CW QSK… another column for your list!

Give me a few days and I will test the radios I currently have available. I have a K3, with the later “K3S” synth boards, an IC-7300, plus a K1, K2 and KX3. I have a KPA500 and a Hardrock 50 amp too. All, except the Icom, are diode antenna change over.

73 Dave
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G4IKZ

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Re: List of radios with silent QSK
« Reply #14 on: August 12, 2021, 11:25:08 AM »

Thanks to all for your comments. Here’s where I am with my own work.

QSK List: Version #1
I have begun to group radios by T/R switching technology. (I include in that any T/R switching included for control of peripherals such as amplifiers). I acknowledge that this is just one aspect of the issue (and G4AON’s comments above in particular). But this is work in progress, I have limited time, and I can’t do it all at once. Groupings are made in good faith based on comments from others. If anybody disagrees with the groupings, or can confirm any, or can tell me which group any other radios belong to then please let me know. Any TS-890S experts out there?

Group 1: Unconditionally Silent QSK
Elecraft K3
Elecraft K4 (?) - confirmation needed
RGO ONE (?) - confirmation needed
Radios in Group 1 don’t use any electro-mechanical components for any T/R switching functions. In that respect their T/R switching will always be silent because they contain nothing that could make a noise.

Group 2: Conditionally Silent QSK
No radios yet identified.
T/R switching of Group 2 radios might not be silent under all circumstances. But there is at least one operating condition where they can be. This group could (for example) include radios whose only T/R relay is used for controlling an external amplifier, but only if all such relays can be disabled, either via hardware link or configuration menu. Radios in this group are fundamentally different to those in Group 1, but that doesn’t necessarily make them ‘inferior’ to those in Group 1.  A  radio that is in Group 2 because it has the option to use either a transistor or a relay to control an amplifier is actually more flexible than a Group 1 radio in which there is no relay option. In that case the Group 2 radio is only inferior (from the QSK viewpoint) if that relay cannot be disabled.

Group 3: Quiet QSK
IC-7610 (?) - confirmation needed
Radios in Group 3 have at least one T/R relay that cannot be disabled. But radios only belong to Group 3 if all such relays are very quiet ‑ such that they would not normally be heard without deliberately listening to them.

Group 4: Loud QSK
FTDX10 (?) – confirmation needed
FTDX101 (?) – confirmation needed
IC-7300
Radios in Group 4 have at least one T/R relay that cannot be disabled. But a radio will only belong to Group 4 if at least one such relay is always audible without special effort.
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