Splattermaster

[k4kyv]

The scope is just as useful for monitoring SSB as it is for AM.  Remember the famous "Christmas Tree" pattern that at least used to be depicted in the ARRL handbook, to show what a clean SSB signal should look like?  I'd bet there would be a lot less splatter from over-driven SSB linears and other mis-adjustments if more slopbucketeers used a monitor scope and knew how to interpret the envelope pattern.

[Pete, WA2CWA]

The scope is just as useful for monitoring SSB as it is for AM.  Remember the famous "Christmas Tree" pattern that at least used to be depicted in the ARRL handbook, to show what a clean SSB signal should look like?  I'd bet there would be a lot less splatter from over-driven SSB linears and other mis-adjustments if more slopbucketeers used a monitor scope and knew how to interpret the envelope pattern.

Most of us here probably agree that a monitor scope to monitor the transmitted waveform, regardless of the mode, is a good thing. But again, your statement, "none of the major ham equipment manufacturers any longer produce a modulation monitoring scope capable of viewing envelope and trapezoid patterns". Why would a current manufacturer spend the design and manufacturing dollars to develop a monitor scope to monitor transmitted output today when their advertised transceiver hype claims great specs for transmitted output of their rigs? Whether they're all true or not or if it's just operator screw up, it makes no sense to me for them to offer a monitor scope product that might show their transceivers not functioning per their specs regardless of the reason(s).

[K5UJ]

they should offer such a product if they make and sell a complete line i.e. rig and rf power amp because the amp can be improperly operated or overdriven.  for example both yaesu and icom make s.s. amps to go with their rigs (or used to, I assume they still do) and a monitor scope is needed because those s.s. amps especially can be turned into real grunge factories when overdriven.

[k4kyv]

But could you expect those Hammy Hambones who have managed to pass the Extra Class test, but who cannot decipher the elementary instructions in the Handbook on how to assemble a half-wave coax-fed dipole, so they post on-line seeking someone to explain exactly how to do it, to be able to interpret the envelope pattern as displayed on a scope?

More likely, the reason the major appliance manufacturers no longer offer a monitor scope in their product line is that there wasn't enough demand for them. If enough customers were willing to pay money for a scope, you could rest assured that Yaecomwood would offer them for sale.

Otherwise, why doesn't some after-market manufacturer offer a universal monitor scope, something on the order of the Heathkit HO-10 (but hopefully better quality), or the YO-100? (Maybe they do, but I haven't noticed any ads lately for such a product).

[WB2CAU]

Would a single-purpose, low production quantity, scope be economically feasible?  I doubt it.  Better off buying a run-of-the-mill, general purpose oscilloscope and dedicate it to modulation waveform monitoring.  

I see relatively modern, functional oscilloscopes available on the used market these days for under $100.  I bought one myself this past October for $55 at the Hall of Science hamfest.  

If someone wanted a smaller footprint scope, the trend now is to portable LCD display models.  But they are more pricey.

Eric

[Ed/KB1HYS]

The plain truth is, you couldn't compete with the inexpensive analog scopes that are being dumped onto the used equipment market now with a dedicated monitor.  I have two decent scopes which I got for $0 because they were analog and considered obsolete. They also only got to 50 or  60Mhz which is pretty low.   Industry is only buying the new PC based Digital Ghz range scopes, and few are paying to repair analog jobs.

Now, getting operators to actually learn how to use those scopes?  Whole nother animal. 

Remember lissajous figures?  A scope and low voltage AC signal and you can diagnose componets right in the circuit.  I learned to evaluate diodes that way. 

[k4kyv]

I have heard complaints that the new PC based Digital Ghz range scopes scopes don't always display all waveforms correctly. A hamfest bargain might actually work better. And I am aware that "digital" and LCD don't necessarily mean the same thing. But if CRT TVs and computer monitors have become obsolete, no doubt the same thing applies to oscilloscopes.

Many of us buy used radios and components at a fraction of the original price, but that is not to say that everyone who would want a monitor scope would go the $50 used hamfest bargain route.  Those who fork over $10 grand for a transceiver probably wouldn't be all that concerned about the price of a quality, state-of-the-fart monitor scope. And if enough of the hams who need to use a monitor scope actually purchased one, it wouldn't be a low production quantity item, any more than an accessory like an antenna tuner.

I did go the cheap route myself.  With a Heathkit HO-10 for $30 at a hamfest.  Spent a few hours getting it to work right, and then modifying out some of the original design flaws, like a focus problem and internal 60~ hum that not only affected the X and Y axis, but the Z axis (brightness) as well.  The manual says the hum is inherent to the design, but "shouldn't" be a problem given the purpose of the scope - modulation monitoring. I was able to clean it up with a little effort, so I know the Heath engineers could have done the same, but just didn't want to bother.  Since I purchased the original one, I have picked up 3 more basket cases for little or nothing for spare parts and spare CRTs, which like everything else, appear to be turning to unobtanium. I have already had to swap out the power transformer with one of the spares.

[W0BTU]

But could you expect those Hammy Hambones who have managed to pass the Extra Class test, but who cannot decipher the elementary instructions in the Handbook on how to assemble a half-wave coax-fed dipole, so they post on-line seeking someone to explain exactly how to do it, to be able to interpret the envelope pattern as displayed on a scope?

Things sure have changed, haven't they? QST and the Handbooks used to regularly feature monitor scope construction articles. I remember sitting in high school study hall around 1969 tracing the schematics for one of those articles.

[flintstone mop]

To see the Slattermaster in all of his glory you would need a spectrum analyzer OR Panadapter type display to see a wide signal and distortion products when the higher emphasized freqs are transmitted.
I bet this guy is using an FM limiter with the 75 microsecond pre-emphasis. And killing that poor BC TX.
Fred

[KM1H]

You can get a HP-141T system with the 110mc plug-in for $250 or less these days in working condition. All discretes and easy to work on, usually just needs caps and a few resistors. The only hard part to find is the CRT.

Back in the late 90's HP was offering tremendous trade in deals on them for the latest and greatest. The Test Equipment manager at work swapped me all good modules and mainframes for hamfest junkers since HP was just going to destroy them. I wound up with 4 complete systems with lots of the extras. Sold off 3 when I got a chance at a later model and moved the other over to the ham operating section and later picked up a couple of dead Kenwood station monitors and fixed those.

A 40MHZ dual trace Leader can be found for $20 and a 50MHz Tek 453A for not much more if you just want to look at waveforms but as Fred mentioned it doesnt tell you much except to get in the ballpark.

The old Hallicrafters SP-44 Panadaptor is good on a 455kc IF before any filtering and I use one on 10M to spot carriers during openings.

[K9PNP]

I don't see what the big deal is on making a mod scope.  Had an old Heath O-10 scope given to me a few years ago because it "didn't work".  Replaced the fuse and it worked as good as it could considering its age.  Never could get the vertical centering control to center the dot, so pulled the vertical amp tubes and replaced 1 way out of range resistor and it centered itself.  Just used 2 caps to couple the RF from a homebrew 'tuner' to the vertical plates.  Ran the audio into the horizontal front panel input.  Works fine.  Cost me nothing except junk box parts.

I will have to agree that there are those with licenses that can't change mikes or fuses without help.  Guess I've learned a few things over the years;  especially since I hate to spend money when I have all the parts, more or less, to build it.

[WA3VJB]

Why would a current manufacturer spend the design and manufacturing dollars to develop a monitor scope to monitor transmitted output today

For the same reason they came up with waterfall and panadaptor displays. They're fun to look at, even for idiots.

[Opcom]

We don't need more regs but it it were required that every commercially sold 'ham' rf amplifier incorporate at least a 3" CRT based monitoring scope, it would help a lot to educate even the most ignorant of hams including those who are merely attracted to shiny objects.

By default the thing would be "on" with the beam biased off except during transmit and then on TX, showing the RF waveform against a 15-120Hz sweep. (for the cheap seats, just derive 3-4x overscan from transformer secondary as is done in the Catalyzer et. al.)

It is a small increase in manufacturing cost IIAR 3" flat-face CRT with P1 or P2 phosphor are still made with decently low V/inch deflection sensitivity and cost about $100 retail.

High voltage is already present except for SS amps (where the crazy-high cost of the amp would further minimize the cost impact of a 2-3KV 2mA supply), and $10 worth of extra parts would do the job.

For fussy folks, a dynamic focus voltage is easily implemented with passives so that the beam is sharp in center and edge.

Balanced drive to the plates is also in order but that is a little extra cost. Unbalanced drive can result in slight defocusing.

All adjustments could be internal as there is little need for user alignment if operating voltages are steady. There's plenty of plastic in today's amps so there's a place to mount any pots etc. that might be at HV.

Think of it as a feature, and the better amps might have real front-panel scope features like front panel centering, focus, intensity, astigmatism, rotation adjustment, external connections for RX IF monitoring (small broadband amp for driving the vertical plates), and other pretty stuff.

CRTs do not change V/in sensitivity much over their lifetime and it depends almost completely on accelerating voltage so the scope could also be factory-calibrated to indicate max. peak or carrier (RTTY and CW) power within 5-10% and no front panel controls are really needed. A nice graticule with a traditional zero, 50%, and 100% line for hammy alignment of carrier and observation of PEP.

Trace intensification at flat topping and at >100% negative modulation would be a plus and can be done with passives.

I'd like to say make it impossible to turn off the scope, but someone who likes to sit in the dark would dislike that because of the relative brightness. A brightness pot would be a minimum necessary control. (BTW cutting heater volts in a CRT is a sorry way to turn it off because it can strip the cathode, but the costly old IC-9000 does it that way)

The reason I say CRT and wrote all that good stuff is that a cheap LCD updates at a fixed rate as a fact of its design and requires costly a-d conversion and what amounts to another processor to make it work, and further does not have enough 'points' to avoid aliasing the RF signal so that means downconversion and more proicessing to create a 'fake' evelop that is a copy of what is coming in. A LCD having a fixed update can only accept sub-harmonics of the update frequency. Typical TV set LCD at 30Hz, would give only usable 30, 15Hz, and 10Hz sweep rates.

And LCD scopes besides cost are unpleasant:
http://amfone.net/Amforum/index.php?topic=27948.0


Force hammy hambones to have scopes in their amplifiers!! - I am so mean.. But it would educate them right away, and in their faces, how to adjust and drive them. Its one thing to blow and go, but if the scope is right there scolding you each time you throw a mess onto the air it is pretty damning.

Sorry, no solution yet for those running modulated amplifiers. One problem at a time.

[ke7trp]

I have a $100 spectrum analyzer and you can too. Its called a Soft66LC2.  It costs about Cnote, Plugs into the computer and with a small wire antenna laying on the table, you get a fantstic output scope.  It also makes nice reciever.  lDepending on your computer you will get 200KC wide.  100 up and 100 down of center freq.  I get about 120 on my laptop.

I monitored my big TX's signal the other night. Nothing new here.. Close that base line on my Oscope and there she goes, big time wide.   Back it off to 80 negative max, set peak limiter there, 10 KC wide. No splat. 

I am over the super hifi sound.  I backed the high cutoff way down and narrowed things up 6 months ago. I just want a nice clear TX with some punch.

C

[k4kyv]

I don't see what the big deal is on making a mod scope.  Had an old Heath O-10 scope given to me a few years ago because it "didn't work".  Replaced the fuse and it worked as good as it could considering its age.  Never could get the vertical centering control to center the dot, so pulled the vertical amp tubes and replaced 1 way out of range resistor and it centered itself.  Just used 2 caps to couple the RF from a homebrew 'tuner' to the vertical plates.  Ran the audio into the horizontal front panel input.

I had to replace the HV filter cap.  They seem to go out a lot.  Don't remember the exact value, but it's rated at  something  like 1 kv at a fraction of a mfd. That took care of the z-axis (brightness) hum modulation.  I got rid of most of the X-Y axis hum by replacing the piece of scrap tin Heapshit had wrapped round the neck of the CRT with a real black metallic CRT shield salvaged from some old piece of surplus equipment I had scrapped. Then re-routed the filament line, using a wire lead for both sides of the filament line instead of using chassis for ground return. Pulled out the vertical amp tube and the slopbucket two-tone test generator, to save wear and tear on the power transformer, which also has a reputation for crapping out (I have already gone through one).  I also made some mods to the focussing circuitry and astigmatism adjustment, so that I get a fine dot on the screen instead of a fuzzy blob.  It's a pretty good monitor scope now.  I plan to try balanced rf feed to the vertical plates to see if that cures the skewed display pattern.

I remember that thread now; that's where I heard it mentioned about digital scopes sucking for modulation monitoring.

[Pete, WA2CWA]

I don't see what the big deal is on making a mod scope.  Had an old Heath O-10 scope given to me a few years ago because it "didn't work".  Replaced the fuse and it worked as good as it could considering its age.  Never could get the vertical centering control to center the dot, so pulled the vertical amp tubes and replaced 1 way out of range resistor and it centered itself.  Just used 2 caps to couple the RF from a homebrew 'tuner' to the vertical plates.  Ran the audio into the horizontal front panel input.

I had to replace the HV filter cap.  They seem to go out a lot.  Don't remember the exact value, but it's rated at  something  like 1 kv at a fraction of a mfd. That took care of the z-axis (brightness) hum modulation.  I got rid of most of the X-Y axis hum by replacing the piece of scrap tin Heapshit had wrapped round the neck of the CRT with a real black metallic CRT shield salvaged from some old piece of surplus equipment I had scrapped. Then re-routed the filament line, using a wire lead for both sides of the filament line instead of using chassis for ground return. Pulled out the vertical amp tube and the slopbucket two-tone test generator, to save wear and tear on the power transformer, which also has a reputation for crapping out (I have already gone through one).  I also made some mods to the focussing circuitry and astigmatism adjustment, so that I get a fine dot on the screen instead of a fuzzy blob.  It's a pretty good monitor scope now.  I plan to try balanced rf feed to the vertical plates to see if that cures the skewed display pattern.

I remember that thread now; that's where I heard it mentioned about digital scopes sucking for modulation monitoring.

FYI: Heathkit made an O-10 oscilloscope; you have a HO-10 monitor scope

 

[flintstone mop]

I think the addition of any type of  'scope to many Ham ops would be another hurdle to understand the display.
It would be eye candy and the more mis-adjusted the TX the prettier display.

[K5UJ]

I pulled caps out of a derelict HP scope I got somewhere (junk swap?) and put them in sb610.  I run the 610 off buck transformer like any older tube gear--hope that preserves p.s. transformer.   the heath monitor scopes got worse with time instead of better.  the CRT screen area seems to have gotten smaller.  with the SB614 the CRT screen is so tiny the 614 is useless to me.  IIRC that h.v. filter cap in the 610 (and I think also the HO-10) is 1.6 KV and .1 uF.  Another thing I did was not run the RF through the 610 but rather through a T connector with the vertical part of the T connected to the 610 and the RF through the top of the T to the antenna.  Seems to work just as well.  

I heard that at the last Hamvention there was some outfit selling these Chinese flat screen scopes, brand new with all kinds of modern high tech digywigy features for around $200 each.   I saw one at a friend's shack, Greg WB9DNZ, and it looked real nice, small and lightweight but $200 still too much for me.

[Opcom]

The SB-614 really uses a 3" tube but wastes some of it by using a smallish escutcheon to make the screen look rectangular. Kind of stupid but I guess they wanted that modern look. They could have used a 4MP1 rectangular tube but it cost more than the 3RP1 they had been using. The SB-614 uses balanced deflection for RF and sweep. It also has the trapezoid 'generator' form of amplifier linearity indication that some people don't like.

The SB-614 is a little on the complex end but I agree that basic mod scopes are simple. What percentage of hams can even make something that simple? Lots of hams would have trouble making a 12V power supply. For them a brand new $200 mod scope is a good deal.

Its likely 5" CRTs are no longer made and that is a pity because the patterns are much easier to see at a distance meaning the monitor does not have to occupy high value space right in front of the operator.

[Bill, KD0HG]

The reason the major appliance manufacturers no longer offer a monitor scope in their product line is that there wasn't enough demand for them. If enough customers were willing to pay money for a scope, you could rest assured that Yaecomwood would offer them for sale.

Nobody will spend the money on them until there is once again a threat of being busted for technical violations.

I can't imagine operating the station without the reassuring green glow of the Tek 323 scope sitting on top of the R-390. And the scope was free, all I had to do was replace a power supply filter cap.

Which brings up a question..What is the best English word to say when looking at a modulation envelope in order to keep the display in sync? Mmmmm?

Bill

[k4kyv]

It also has the trapezoid 'generator' form of amplifier linearity indication that some people don't like.

If you are referring to that pseudo-trapezoid pattern whose audio source is derived from rectification of the rf signal that is fed into the scope, it does indicate amplifier linearity: the linearity of the vertical  and horizontal amplifiers in the scope.  Useless for checking modulation linearity of the modulated stage. It accurately indicates percentage of modulation, but so does the regular envelope pattern.

[KM1H]

3" CRT's were in the CE 100/200V, Cosmophones and maybe others.

Heath and Kenwood made lots of station monitors and they still sell for big bucks on the used market.

I dont see it a big deal to add a SS CRT in modern rigs or sell as an outboard option. For the idiots (90+% of current hams) have a bell go off when things are set incorrectly and make it impossible to disable

[WA3VJB]

I have a NOS CRT for a Tektronix 500-series scope.

PM or email me.

[W1AEX]

Real scopes have square screens Paul! I paid 20 bucks for this Tek 485 and got a clean Tek 453 from a neighbor for free. Life is good!

[Steve - K4HX]

A scope is not needed to indicate linearity. A simple red/green light could show when something is being driven too hard. This would make more sense for the mass produced transceivers. Given most, if not all new rigs are DSP based in one manner or another, all this could be done with the DSP.

The vertical and horizontal amplifiers in any good scope (ones you can buy for $50-100 at most fests) will be linear, especially at audio frequencies. The SB-614 and the Hohos are junk and should not be used for this or any other waveform monitoring.