Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

   Home   Help Search  
Pages: [1] 2 Next   Go Down
  Print  
Author Topic: What Makes a Good CW Transceiver?  (Read 7565 times)
AE5QB
Member

Posts: 269




Ignore
« on: February 10, 2011, 05:06:42 PM »

Two questions.  I have a Yaesu 857D which I like a lot but must admit I haven't operated any of the high priced rigs to compare it to.  I read about how the CW break-in is really inferior on this transceiver.  Again, I don't know the difference.

So would someone mind explaining to this CW newbie what qualities make a good CW break-in transceiver?  What makes the Ten-Tec or K1,2,3 superior CW machines?

Also, could you give me some general idea of what to look for when setting break-in.  Not specifically to the FT857 but generally what should I look for.  I have the delay set to where it doesn't drop transmit between characters but does between words.  I am fairly comfortable with it as is, but maybe I just don't know enough to know better.

Thanks!

Tom
AE5QB
Logged
STAYVERTICAL
Member

Posts: 864




Ignore
« Reply #1 on: February 10, 2011, 08:08:12 PM »

Hi,

The ideal setup would be a break-in time of 0, so that the receiver was active when the key was up.
Many transceivers use relays to switch between TX and RX, so that is always going to mean a time delay in switchover.
In addition, relays tend to be noisy and some transceivers also switch fans on during TX, so the whole thing becomes very disconcerting.

I used to use break-in when I was at sea, and from my experience, especially in the tropics at around 500Khz, it was a pig to use, like a hurricane between dits.
The reason for break-in is simply to enable the other station to interrupt you and get a repeat or some other similar reason.
But if you are not into CW traffic nets, I would not bother with break-in, since most CW stations don't assume you have break-in in any case.

As regards what makes a good CW transceiver - all of the usual reasons which make a good RX and TX with the addition of some nice narrow sharp I.F. filters, ability to vary the AGC and a peaking filter is nice.


I would not over analyse your requirements for CW, I use the FT897D and find it entirely acceptable for CW, especially with the 500Hz mechanical filter.
The best accessory for CW is the grey matter and will enable you to work and enjoy the mode very much.

73s
Logged
N6GND
Member

Posts: 375




Ignore
« Reply #2 on: February 10, 2011, 10:59:42 PM »

Stayvertical's advice is excellent.

Until your code speed gets to about 25 wpm and your operating skills are highly-refined, being able to listen between words is more than all you need. For break-in with zero delay to have any utility, operators at both ends need to be skillful and the operating context (for example a high-speed net actually handling traffic) appropriate. Otherwise, it makes no difference.

I think CW is fun because it does require higher cognitive skills, even with seemingly simple tasks like tuning your receiver. You need to be able to get your radio reliably to zero beat very quickly and to know exactly where in your radio's i.f. passband the signal you are trying to interpret lies. This allows you to deal efficiently with interfering signals. It also allows you to use the narrowest possible bandwidth so you can increase the apparent signal to noise ratio. This allows the pulling up of very weak signals into readiblity. And that's what makes CW work so well when other modes can't.

Also, by listening to highly-skilled operators (usually sending at 25 wpm or more), you get some wonderful ideas about how to communicate efficiently and clearly. You come to realize that the best CW can be elegantly minimalist and something very different from the run-of-the mill QSO which usually involves sending far too many characters--many more than are actually needed most of the time.

Last, which should be obvious, is being able to send absolutely clear code with appropriate letter and word spacing.

Your gray matter is your best signal processor, but you've got to take the time to train it. Which is, again, where the fun lies.
Logged
K3TN
Member

Posts: 285


WWW

Ignore
« Reply #3 on: February 11, 2011, 03:04:12 AM »

Sounds like you have break-in set up just fine - that's exactly how I've done it for years. Many like full QSK, but many don't - what you are comfortable with is best.

Good CW rigs: its all about filtering. On transmit, that basically means lack of key clicks. You'll see in QST reviews and in forum comments that some rigs have a CW transmit waveform that leads to key clicks, generally considered bad form.

On receive, a front end that has enough filtering to not get overloaded with strong signals on the low bands and that doesn't hear CW signals on both sides of zero beat. Generally back end filters to at least get you down to 500hz, some like to go lower than that. Some like audio peaking filters, some don't - I've usually found them to induce more distortion than they are worth, but I use the one in my K3 occasionally now.

There are a few other CW friendly features:
1. A built in keyer with both paddle and key jacks.
2. Notch filter
3. Front panel buttons for a few CW memories

Most modern rigs have all that stuff - the difference is in how easy those features are to use.

I do about 80% CW operating and to me its all about how the receiver sounds in crowded CW conditions. I currently have a TS-850 and a K3 because over the past 20 years they've had what to me were the best sounding receivers on CW. That's a very subjective thing - so, listen to a few at a ham store or hamfest and be subject them to your ears!

73, John K3TN
Logged

John K3TN
N3QE
Member

Posts: 2199




Ignore
« Reply #4 on: February 11, 2011, 08:52:20 AM »

For really, truly, awesome break-in? The K2 and Ten-Tec's don't have it.

What you really need is independent receiver and transmitter. When you hear your own signal (muted) while key-down, that's truly awesome break-in. You are actually listening to the band even when your key is down. And you are hearing what your tone sounds like to the other stations in the vicinity.

Now, the K2 and Ten-Tec's come about as close as you can get with a transceiver.

The only "transceiver" that comes close to that joy of QSK, is the Heath HW-16. Which isn't really a "transceiver" it's a transmitter and a receiver in the same box (to which you will want to add a VFO!)

I personally don't think a transceiver needs paddle jacks and key jacks and memories. All that resides in the keyer. Of course I'm an old fart and none of my rigs have a keyer in them at all so it's all outboard. And I just parallel my straight key with the keyer so I use whichever I want whenever I want.

Tim.
Logged
AE5QB
Member

Posts: 269




Ignore
« Reply #5 on: February 11, 2011, 09:49:31 AM »

...What you really need is independent receiver and transmitter. When you hear your own signal (muted) while key-down, that's truly awesome break-in. You are actually listening to the band even when your key is down. And you are hearing what your tone sounds like to the other stations in the vicinity...

Tim.

OK humor me, pls. How does this work?  Seems to me that if you are sampling your own signal at even a very low level it is going to overload the receiver.  Also how does it work to simultaneously receive break-in traffic, sample your own signal, and transmit full power over the same antenna without overloading the receiver?  Even if using two antennas, I would think the receiver would be so swamped with the transmitted signal that break in traffic wouldn't have a chance.  Now if one were working split, maybe.  I am not questioning if it works, my mind just can't get a handle on how it works.

Logged
KE4JOY
Member

Posts: 1377




Ignore
« Reply #6 on: February 11, 2011, 11:29:36 AM »

This is how I operate CW separate transceiver with a remote receiver.

I can turn the output of the xmitter all the way down and 'spot' the signal on the receiver.

During 'normal' operation the second receiver is muted (very quickly) when the key is down and unmuted when the key is up. Its not 'true' QSK but its so fast I can hear the receiver between the dits at around 20 wpm.

The only time I goof up is when I leave a switch on the receiver in the wrong position and blast it with a meter pinning signal. The receiver finally recovers but its probably not good for it  Grin

I use an external switch that I built designed by AD5X Ill add the link  Grin

http://www.eham.net/ehamforum/smf/index.php/topic,69975.0.html

This switch has helped the wear and tear of the TR relay of the xmitter as I have it set to a pretty long delay so it doesent bang back and forth at anything less than 20 wpm.
« Last Edit: February 11, 2011, 11:34:39 AM by KE4JOY » Logged
WB2WIK
Member

Posts: 20595




Ignore
« Reply #7 on: February 11, 2011, 11:50:23 AM »

Two questions.  I have a Yaesu 857D which I like a lot but must admit I haven't operated any of the high priced rigs to compare it to.  I read about how the CW break-in is really inferior on this transceiver.  Again, I don't know the difference.

It's mostly a matter of receiver AGC performance, the ability to use a noise blanker without it creating lots of distortion from strong signals in the first IF passband, the ability to key at higher speeds without the transmitter cutting off the leading edge of each dit and dah, making the RF envelope shorter than the actual key-down time, and lots of stuff.  You have to operate a lot of different rigs to tell the difference.

Quote
So would someone mind explaining to this CW newbie what qualities make a good CW break-in transceiver?

All that stuff: See above.

Quote
What makes the Ten-Tecs  superior CW machines?

A lot of stuff in Ten Tec rigs is specifically designed to enhance the code operating experience.  Even my little Jupiter is completely "silent" using QSK (generates zero audible noise at all, keying at any speed) and its RF output envelope at 50 wpm shows complete dits and dahs formed without anything being cut off.  I can turn the AGC down to either very fast or "off" (in which case the RF gain control becomes the active volume control) and hear someone break in between dits at 30 wpm.  But besides that stuff, it's much handier to use: I can change power level or keying speed, or filter bandwidth, or lots of stuff "on the fly" without having to use any menus...just reach up and do it.  It reads out code sending speed (assuming you're using its internal keyer) on the front panel main display screen so you always know what speed you're sending.  I have an FT-857D also (mobile/portable use) and it doesn't do any of this.

Quote
Also, could you give me some general idea of what to look for when setting break-in.  Not specifically to the FT857 but generally what should I look for.  I have the delay set to where it doesn't drop transmit between characters but does between words.  I am fairly comfortable with it as is, but maybe I just don't know enough to know better.

Full QSK means the transmitter turns on for each dit or dah, and turns off completely in between them so you can hear received stations or noise in between each part of a character.  Anything "slower" than that is "semi-QSK," and of course can usually be adjusted to whatever dropout delay you wish, often up to a few seconds.  A receiver must have either extremely fast AGC, or the ability to turn AGC off completely, to really do this properly.

Logged
WX7G
Member

Posts: 6039




Ignore
« Reply #8 on: February 11, 2011, 12:10:36 PM »

I have an FT-857 in the car for mobile CW and a K3 at home for CW. I've been told by one ham that he can hear the FT-857 cutting short the first DIT when I run break-in. It doesn't seem to be a real problem though. My call starts with W and is copied as such and not as an M.

Where the FT-857 and K3 difference shows up is in 160 meter contesting. The FT-857 will fold up and die with super strong signals right next to weak signals. The FT-857 noise blanker is pumped something awful by strong signals on the band. The K3 doesn't care. For everyday use, even DXing, I think the FT-857 is a fine rig.

The ARRL CW DX contest is next weekend. See what you can do with the FT-857.
« Last Edit: February 11, 2011, 03:30:30 PM by WX7G » Logged
K7KBN
Member

Posts: 2802




Ignore
« Reply #9 on: February 11, 2011, 10:35:49 PM »

Back in '63-'66, I operated "QSK", although we never actually called it that.  We used an R-390A receiver connected to a 35' receiving whip which was maybe a thousand feet from the transmitting antenna.  The transmitter was usually an AN/WRT-2, running 500W or more. 

The AGC on the R-390 was super.  You could easily hear the other station or stations in between dits at 40WPM.

N3QE is right.  You really need a separate transmitter and receiver, and separate antennas, a good distance apart.  On an aircraft carrier such as the one I was on, 1000 feet of separation was about as good as it got.
Logged

73
Pat K7KBN
CWO4 USNR Ret.
KB3TXH
Member

Posts: 44




Ignore
« Reply #10 on: February 13, 2011, 07:19:51 AM »

The transmitter was usually an AN/WRT-2, running 500W or more.

Oh, my gosh, I finally heard from someone who actually used the equipment that I helped to build.
One of my first jobs was working in a factory assembly line (1960-1963) , building WRT-1 & WRT-2s.
I must have had my hands in a thousand of them.

Logged
K7KBN
Member

Posts: 2802




Ignore
« Reply #11 on: February 13, 2011, 02:32:27 PM »

Well, my days on the Kitty Hawk were from '63-'66, so I may have cut my teeth on one of your earliest transmitters.  They were fine, rugged and stable, and if your watch station was in the transmitter room, they were fun and easy to tune and operate.

Thanks, Uglystick!
Logged

73
Pat K7KBN
CWO4 USNR Ret.
N2EY
Member

Posts: 3879




Ignore
« Reply #12 on: February 13, 2011, 05:05:44 PM »

My take on what makes a good CW transceiver:

1) Good sensitivity. (so you can hear the weak ones). How much is enough varies with the band and your location.

2) Good selectivity. This doesn't just mean sharp filters or DSP; it means the filter characteristics and placement are optimized for CW.

3) Good "dynamic range". This is actually several characteristics (blocking dynamic range, third-order IMD, phase noise) and I won't give a detailed description.

What matters is that 1), 2) and 3) are put together so as to let you hear the weak ones clearly on a band that's full of strong signals.

4) A nice big tuning knob (2-3" diameter), a slow tuning rate (5 kHz/turn or less) and an easy-to-read dial (doesn't have to be digital, but shouldn't require squinting or a maginifier). The dial drive should have a nice feel and not be tiring to use.

5) Good stability. Doesn't have to be NIST-standard but don't want to go chasing up and down the band.

6) Good clean audio, including the sidetone. While it doesn't have to be hi-fi, low-distortion audio can make the difference between a set that's easy to listen to for hours, and one that's tiring.

7) Defeatable AGC and a good RF gain control. (AGC isn't really needed and often makes things worse).

Cool RIT and split operation.

9) Good clean keying at all speeds. This means no clicks, no chirps, no burps, no short-first-dit, etc. It also means very little tx delay (see below in QSK discussion).

10) Easy to use controls. (Shouldn't have to hunt through menus to turn off the AGC or change the keyer speed, etc.)

The exact choices of a lot of these things is up to the operator, and you have to know your own likes and dislikes. For example, some ops aren't bothered by a tuning rate of 20-25 kHz per turn, which for me is way too fast. OTOH I don't use AGC, which others consider essential.

---

Now about QSK/full-break-in:

First off, understand that true QSK/full-break-in means you can hear between dits and dahs, even at high speeds. IOW, whenever the key is up, you hear the frequency, right down to the noise. (Nobody can really hear the frequency with the key down unless the transmitting and receiving antennas are well separated and the tx and rx are not on the same frequency).   

There are a number of ways to achieve QSK/full-break-in. All of them can be good; what matters is the implementation.

A lot of rigs say they have "break-in" or "semi-break-in" or similar, but what they really have is a form of "keyed-VOX" which lets you hear between words, if it's adjusted that way. A nice feature, but it's not full-break-in. It's just a convenience feature so you don't have to throw a switch.

Whether or not QSK/full-break-in is worthwhile depends on the operator and the kind of operation. Some folks find it hard to copy when they can hear the frequency between dits and dahs, others like it.
Some folks' operation is such that QSK makes a big difference (traffic handling, S&P contesting & DXing) while others don't need it. The ham whose top speed is 20 wpm on a good day may find that a certain rig's QSK is excellent, while another ham who cruises on the high side of 40 per thinks the same rig has terrible QSK.

In theory, there is no reason a transceiver can't have QSK that's every bit as good as separate tx and rx. And some transceivers like the Elecraft K2 are very good.

But not all transceivers do QSK well. Here's one reason why:

Consider the classic separate tx-rx setup that was "state of the art" 40-50 years ago.

Such a setup would consist:

1) Transmitter that had very clean, no-delay keying and was connected to the antenna at all times

2) Receiver that had very fast mute and unmute properties

3) Electronic or relay TR switch that could operate at very high speeds.

There was also a control system (often just a high speed relay) to mute the receiver when the key was down.

With such a system, you press the key and the transmitter emits RF almost instantly. The receiver also mutes almost instantly. Release the key and the transmitter goes quiet while the receiver comes to life. The electronic TR switch keeps the transmitter's RF out of the receiver front end.

Total R-to-T and T-to-R delays in such setups could be held down to a couple of milliseconds, far shorter than a dit, even at high speeds.

Because the tx and rx are almost totally independent, the changeover can happen very fast.

But with transceivers there's often more to be done - it depends on the exact design of the rig. For example, most transceivers use some stages for both transmit and receive, and their changeover takes time.

This time factor is usually most pronounced in the oscillators, which often have to change frequency between T and R. So when you press the key, the transmitter cannot be allowed to emit RF right away; there has to be time allowed for the oscillators to QSY to the new frequency before the transmitter actually keys. When the key is released, the reverse sequence has to happen.

Depending on things such as PLL lockup time, these added delays can be considerable, particularly at high speeds. Look at the high-speed keying pictures in QST Product Reviews and you'll see that some rigs have considerable differences between the key-closure waveform and the transmitted-RF waveform.

Some numbers to illustrate the problem:

When typical plain-language English is sent by Morse Code, the length of a dit (the key-down time) in milliseconds is about 1200/WPM. So a dit at 12 wpm is 100 milliseconds long, while a dit at 60 wpm is only 20 milliseconds long.

If the R-to-T and T-to-R delays can be kept down to a couple of milliseconds, the system will be good at almost all typical amateur code speeds.

But if there's a delay of, say, 20 milliseconds from R-to-T and T-to-R, the picture is quite different. At low speeds the system works fine, but by the time you get to 30 wpm the transition times become a major factor. At 60 wpm you cannot hear between dits at all. During a string of dits, the actual RF is being transmitted during the time the key is up, because the delays are the same as a dit length.

And 20 milliseconds is not a lot of time.

There *are* ways to deal with these issues. The main point is that some rigs deal with them much better than others.

73 de Jim, N2EY

   



 

Logged
W9CW
Member

Posts: 107




Ignore
« Reply #13 on: February 26, 2011, 04:29:23 PM »

Although "late to the party," I had to respond to the posts of K7KBN and UGLYSTICK.  I, too, am very familiar with the WRT-2 and WRT-1, as well as the venerable R-390A.  I was an ET on a tin can from '64 through '68.  Our single WRT-2 was dead reliable, that is until one of the RM's (radioman) shattered the mechanical shaft stops trying to set a land speed record for QSYing while in the Persian Gulf.  We had a tough time getting that RF deck to track, especially the vacuum variable and roller inductor, until we effectively rebuilt it.  On occasion the freq synthesizer would become unlocked (the meter on the synth drawer's front panel would swing back and forth!).  A simple tube replacement quickly fixed that problem.

And, as for xmit and rec antenna separation, we couldn't quite muster 1,000 feet on a destroyer!  Hi...

As for the best CW transceiver, I personally stick to those boxes manufactured in Sevierville, TN.
Logged
W3HKK
Member

Posts: 596




Ignore
« Reply #14 on: February 27, 2011, 02:57:17 PM »

One of the  best  hybrid xcvrs out there is the ft901dm and ft902dm.  Great cw rig with built in keyer.  Great filters and a  handy APF that I use a lot.  The main problem with these is  they tend to drift in their old age, which is mostly a rag chew issue,  This can be fixed by one of the guys who services older rigs.

Terrific new xcvrs include the IC7600, with  built in memories, and a plug in keyboard to edit memories and to directly send rtty and psk on the fly.  No software needed.  The three  settings/roofing filters let you handle most needs with the push of a button....I use 1.2, .5 and .250.  CW keyer speed is a nice and often used  adjustment. A good quiet receiver makes cw less distracting and the ability to program in  contest exchanges available at the push of a button is very nice.  I use a bug not a keyer, which is easily programmed in the 7600 along with break in and semi break in. plus auto cycling cq's.

Logged
Pages: [1] 2 Next   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!