AM modulation monitor

[KB2WIG]

Not watt you asked for, but it is interesting.

http://amfone.net/ECSound/K1JJ8.htm


klc

[KA2DZT]

I use a similar tuned circuit set-up to feed the vertical plates directly, works perfect.

Using broadband xfmr would work but you'll need a high step-up ratio.  The plates need about 50-80 volts.  You'll still need some way to adjust the amplitude.

Fred

[Steve - K4HX]

Just use a modern scope with real vertical amps and almost any RF sample will work.

[WA3VJB]

Really -- "old," but modern laboratory grade analog scopes are $25-$100 on the surplus markets these days, and typically reach up to 250 or 500Mc.

Just use whatever antenna you aren't on the air with as an RF pickup, put the sensitivity in the right zone, and adjust the sweep rate to get a waveform. Most of them have a triggered sweep, so you can prolong the life of the CRT besides.

I wouldn't want to waste my eyesight on those little Heathkit scopes, plus, you have a decent scope for bench work.

... I need to hook up an oscilloscope again, primarily to monitor the AM and CW output from my new 833 linear amp. Maybe someone can give me some advice.

I used to have a scope tuner directly connected to the vertical deflection plates on a cheap Heathkit IO-18 scope. It used a simple balanced link-coupled parallel tuned circuit and covered 80-10. Adjusting the variable capacitor to get the right amount of voltage across the tuned circuit (and the deflection plates) worked beautifully. I could do it that way again, but I am thinking of another design, something more broadband, that will also cover 160 with no adjustment. Has anyone ever used a broadband ferrite-core transformer to couple their KW output signal to their vertical deflection plates?

[Pete, WA2CWA]

This works for aging eyes:

 

[W0BTU]

Just use a modern scope with real vertical amps and almost any RF sample will work.

That's the way to go, yes. But I don't want to move my Tektronix 465B from my lab test bench to my radio operating position. Not only is there not room for it there, but the Heath scope fits on the shelf, and the Heath scope's CRT is larger and easier to see. :-)

[w1vtp]

Just use a modern scope with real vertical amps and almost any RF sample will work.

Yup.  Pretty much.  All I was saying that the scope needs to be pre-calibrated if one is concerned about the 1500 watt PEP measurement. Otherwise go for no flattopping.  Some improvised samplers have the potential of variation of coupling depending on shack variables which negates calibrating for 1500 watts PEP.

W0BTU: One needs only to be concerned if the possibility of exceeding 1500 watts PEP is there. Otherwise, just don't flattop. A scope works for that.

Those miniature scopes really don't make it only to show that things are kinda OK. The "string of pearls" sortof show up on those scopes.

[MikeKE0ZUinkcmo]

I just use this old Gates monitor

[KD0HUX]

I  THINK I WILL BE CALLING STEVE ABOUT ONE.

[steve_qix]

I think some ham is getting a nice Father's Day present!  A woman with no associated ham call (that I could tell) ordered a  Modulation Monitor, which we shipped out on Tuesday - plenty of time for a Father's Day delivery!

[Opcom]

Will the software ask the video card to wait for vertical interval (vertical sync) before updating the video output array to the VGA DAC?

It is beneficial when the internal monitor refresh timing or rate is not the same as the video card's DAC writes. If the graphics card is high performance, the result can be what looks like a tear across the screen, with the current data on the top section and the previous frame's data across the lower section. If the tear is where there is movement (the scope) then it is visible. It was also an issue on older cards and analog monitors but for slightly different reasons.

It can be set in the graphics card user menu, usually, but then it is ON or OFF for all applications unless the menu provides a choice to have it controlled by the application, which is how mine is set.

The software providing this control (flip a bit on) is what I am asking about.

I realize this is a weird question, but I built the new PCs here somewhat better than the previous ones so it comes up.

Thank you.

[steve_qix]

Will the software ask the video card to wait for vertical interval (vertical sync) before updating the video output array to the VGA DAC?

It is beneficial when the internal monitor refresh timing or rate is not the same as the video card's DAC writes. If the graphics card is high performance, the result can be what looks like a tear across the screen, with the current data on the top section and the previous frame's data across the lower section. If the tear is where there is movement (the scope) then it is visible. It was also an issue on older cards and analog monitors but for slightly different reasons.

It can be set in the graphics card user menu, usually, but then it is ON or OFF for all applications unless the menu provides a choice to have it controlled by the application, which is how mine is set.

The software providing this control (flip a bit on) is what I am asking about.

I realize this is a weird question, but I built the new PCs here somewhat better than the previous ones so it comes up.

Thank you.

I know the effect you are talking about.  I have seen this with full motion video on certain monitor/system combinations, but this is _NOT_ an issue with the Mod Monitor on the same equipment.  The graphics engine in the Mod Monitor does small and very selective updates to the screen and uses the lowest level system calls to do the job (where you can actually write to a small portion of the screen and that's what is updated - and, more importantly, the update is not done unless the video subsystem is ready).  I am very sensitive to tearing effects and other video artifacts, and such effects are definitely not there in the Monitor.

We have, at this point, and with the installed base of Mod Monitors, run on a very large number of systems and combinations.

In my own shack, the Mod Monitor is running on a 10 year old Pentium 4, 1 gHz with a very garden variety graphics adapter and an OLD LCD monitor.  The system is so bad that Internet Explorer will actually NOT run correctly, (I.E. is painfully slow due to the poor machine/graphics performance), but the Mod Monitor runs perfectly and looks great!  It is a very efficiently written piece of software.

[Opcom]

That's great. I'm glad you care enough to do low level calls.

[K7JEB]

Has anyone tried to use the AMM-SD1 with a transmitter using controlled-carrier modulation such as the Heathkit DX-60?  Is the monitor able to establish a reference carrier level when the carrier varies at a syllabic rate?  Is there some minimum time required for the monitor to set itself up before displaying an accurate reading?

And what about this downloadable software that runs the indicators on the host computer?  Where is that on the REA site?  I don't think anyone answered W8FAX's question about that.

Jim, K7JEB

 

[steve_qix]

Monitoring controlled carrier accurately would be very challenging    The change in carrier level will be picked up as modulation.  Controlled carrier also causes problems with the AGC of many receivers.  If the AGC at the receive end is sufficiently slow to remove all low audio frequencies from the AGC control voltage, it will also have difficulty following the controlled carrier.

I've modified a number of DX-60s and DX-40s.  Always best to go straight screen modulation.  Properly done, screen modulation is capable of incredible audio fidelity.

As far as a software demo for the AMM-SD1, we haven't put up an "official" demo download yet, but if you send an email to support@radioassociates.com, we can send you a link to a demo    I think it's probably time to get a demo download out on the R.E.A. website anyway.

Regards,

Steve

[Opcom]

The problem I have is I like Stand Alone units and don't like having to have to tie anything into a computer for it to function. I like the idea of the older Rack Mounted unit that has everything self contained.

A rack-decor compatible application could be a self contained fanless PC fitted to the front of a rack, or, a panel display and a remote self contained PC mounted wherever. These solutions are rather common nowadays and used ones are fairly cheap.

Some have solid state disk for the o/s and some have touch screens. all kinds. The only task is to pick one with a width that fits the rack or cut a panel for a small one.

If the unit is mounted so that it's flush, there is no ugly display panel sticking out from the rack. An alternate function is with camera inputs to view the various tubes which may not easily be seen in some equipment.

[w9ac]

Received mine a few weeks ago.  One of the most impressive pieces of hardware I've used.  as other have noted, the software runs efficiently and does not drag down other running applications.  I'm using WIN XP on a crippled Dell w/ Intel Core 2 Duo CPU, 2G RAM.

The only change I would make is to replace the two 1/8" TRS jacks with a BNC for sampling and RCA female for audio.   I really detest 1/8" hardware as good connectivity depends on a single-point contact.  I took apart the processing unit and discovered that Steve is using PCB-mounted connectors.  It's a very efficient PCB layout.  A connector change *can* be done, but with some effort.   I would gladly pay a bit extra just to have some higher quality connectors.

Paul, W9AC       

[steve_qix]

Received mine a few weeks ago.  One of the most impressive pieces of hardware I've used.  as other have noted, the software runs efficiently and does not drag down other running applications.  I'm using WIN XP on a crippled Dell w/ Intel Core 2 Duo CPU, 2G RAM.

Glad you like the Monitor    There's one guy running the software on an old Pentium III, which is definitely unsupported - and it works just great.  We figured a Pentium IV was about the lowest configuration that would be valid because there is a lot of math going on, etc.  The software is very efficiently written and every possible optimization was used to minimize CPU and other resource usage while keeping the real time performance.  The oscilloscope display is the most mathematically complex portion of the Monitor's display.

The only change I would make is to replace the two 1/8" TRS jacks with a BNC for sampling and RCA female for audio.   I really detest 1/8" hardware as good connectivity depends on a single-point contact.  I took apart the processing unit and discovered that Steve is using PCB-mounted connectors.  It's a very efficient PCB layout.  A connector change *can* be done, but with some effort.   I would gladly pay a bit extra just to have some higher quality connectors.

Paul, W9AC       

We went back and forth quite a bit about connectors, and finally decided on the 1/8 inch jacks because they are just so common.  We did choose very good quality connectors, and have not had any trouble whatsoever in the field.  The AMM-HF1 hardware monitor (from a few years back) also used 1/8 inch jacks.  Only audio frequencies are sent over the 1/8 inch connectors.  All RF stays at the SO-239/PL-259s connectors at the input side of the pickup unit.

We've just about sold out of the first production run of Monitors, so it's been pretty popular so far.  Even a few CBers have purchased a Monitor.  Some of the email communication with these guys has been very interesting 

[w9ac]

We went back and forth quite a bit about connectors, and finally decided on the 1/8 inch jacks because they are just so common.  We did choose very good quality connectors, and have not had any trouble whatsoever in the field.  The AMM-HF1 hardware monitor (from a few years back) also used 1/8 inch jacks.  Only audio frequencies are sent over the 1/8 inch connectors.  All RF stays at the SO-239/PL-259s connectors at the input side of the pickup unit.

Steve, perhaps for the next production run, you may want to consider a high-quality RCA jack option for both the sample and audio jacks.  They're just as common and inexpensive as 1/8" TRS jacks -- but the inner conductor contact point mates with significantly more surface area that also resists twisting and slippage.  Unlike the TRS, the inner and outer RCA plug conductors form a grip on the jack. 

Another benefit, is that there's essentially nothing but generic 1/8" TRS hardware/cable on the market, and most cables today use a foil rather than a braided shield.   By contrast, someone who wants to upgrade to a better RCA connector or cable with braid can look to vendors like Neutrik and Switchcraft.

We've just about sold out of the first production run of Monitors, so it's been pretty popular so far.  Even a few CBers have purchased a Monitor.  Some of the email communication with these guys has been very interesting 

It's one of the best performing devices I've ever used, Steve.  Thanks for making it available to us.

Paul, W9AC