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Mod Monitor Question

C

cdkirk

I have a TFT 844 Mod monitor w/o manual that is our sole monitor. I'm obviously concerned about correct calibration. Does anybody have any knowledge on the correct procedure for calibarting the meter's and peak leds? Had hoped that TFT would have the manual posted on their site. No luck though...

Thanks!
 
Call them. Darryl Parker will be happy to connect you to the right person for the correct information. He's been with TFT for many years.
 
Studio1 said:
Calibrating the meter's what?
Click to expand...

I was referring to calibrating the meter and peak led's to 100% modulation. Calibrating the meter to 100% appears very straightforward. However the peak LED's are another story.
 
Good luck. I had a TFT unit and besides wanting a million dollars for the replacement manual they never seemed all that forthcoming with information when it came to non current model device. Whenever possible I'll stick with Belar. In fact I'm trying to find some AM and FM monitors for a school station I'm building and someone gave us a TFT unit which is probably going to sit on the shelf until I let the kids "have at it."
 
I would give them a call. They probably have manuals on pdf's. For years I used 844 A's since they could monitor the competition. When working properly there is nothing wrong with a TFT 844 A. Back in the day, most major market FM stations had TFT's or QEI's because of the tuners. Belar's were usually absent.
 
I'm going to try another call Monday. I had called about two weeks ago and talked to somebody in "tech support" that was not real helpful. I asked him the same questions I posted and all he would tell me is I needed to send it back to them to calibrate it. He said he could send me a new manual for $75.00. I really felt like he went out of his way to not answer my questions.

I've called TFT in the past with a few EAS issues and had always gotten in touch with somebody helpful.

It's really hard to imagine why they couldn't pay some office help a few bucks and have them scan the manual and post it on their web-site.

Argh
 
cdkirk said:
I'm going to try another call Monday. I had called about two weeks ago and talked to somebody in "tech support" that was not real helpful. I asked him the same questions I posted and all he would tell me is I needed to send it back to them to calibrate it. He said he could send me a new manual for $75.00. I really felt like he went out of his way to not answer my questions.
Click to expand...

This is the exact same experience I had in the past, which is why I would go with Belar or QEI as first choices. I ended up restoring an old TFT FM monitor by drawing my own diagrams and going from there. Belar had been extremely helpful with supporting their older products - I would buy and use their gear in a heartbeat.
 
I expect they make a dollar or three off manual sales. We always referred to them as Toys From Taiwan in polite company, and Touchy ------- Technology in not so polite. Their stuff is capable of reasonable performance when it is working, but isn't as rugged or robust as Belar's. I always put the 844 or the QEI in the studio where the program folks could look at the Other Guys, and the Belars at the transmitter where I could feed them a cavity sample and see just what the hell was going on in the transmitter.

Darryl Parker is a genuinely nice guy, and has tolerated some of the grief I've aimed his way over the years like the gentleman he is.
 
littlejohn said:
I always put the 844 or the QEI in the studio where the program folks could look at the Other Guys, and the Belars at the transmitter where I could feed them a cavity sample and see just what the hell was going on in the transmitter.
Click to expand...

Anybody have opinions on Innovonics Mod Monitors? Price seems great for features. How are they for reliability, accuracy, etc..
 
cdkirk said:
littlejohn said:
I always put the 844 or the QEI in the studio where the program folks could look at the Other Guys, and the Belars at the transmitter where I could feed them a cavity sample and see just what the hell was going on in the transmitter.
Click to expand...

Anybody have opinions on Innovonics Mod Monitors? Price seems great for features. How are they for reliability, accuracy, etc..
Click to expand...

I bought one (FM) about a year and a bhalf ago for one of my contract stations. I LOVE IT. Preselector works great, easy to read, and lightweight enough to take between stations or to the transmitter site w/o problems. Great unit for the price.
 
I don't like TFT as a company, but I have to say I've used their AM mod monitors with good success. With that being said, the best method to be totally sure an AM is modulating properly is to use a scope and look for the pinch-off. Mod monitors are a nice thing to have, but a scope and a person that knows how to look for the right thing is dead accurate. Overmodulation to the trained eye is super easy to see. Go find an old scope that works ok and you'll have something that will tell the truth every time.
 
cdkirk said:
Anybody have opinions on Innovonics Mod Monitors? Price seems great for features. How are they for reliability, accuracy, etc..
Click to expand...

I know two people who love the Inovonic units - I just wish I had the budget to install them where I need them. Nice bargraph display and simple to use.

While perhaps not nearly as accurate as a monitor with a bargraph display, I still have a fondness for the Belar analog meter type units (I suppose it's just an "old school" thing with me). I worked with a ModSci ModMinder when they were popular and it was ok, but you needed the computer display to see anything other than the few display elements on the box.
 
OKCRadioGuy said:
I don't like TFT as a company, but I have to say I've used their AM mod monitors with good success. With that being said, the best method to be totally sure an AM is modulating properly is to use a scope and look for the pinch-off. Mod monitors are a nice thing to have, but a scope and a person that knows how to look for the right thing is dead accurate. Overmodulation to the trained eye is super easy to see. Go find an old scope that works ok and you'll have something that will tell the truth every time.
Click to expand...

I like to hook up modulation audio to one axis, with RF on the other, which gives you what some call a "trapezoidal" display.

it gives you quite a bit of information. You can see overmod, you can seen non-linearity, and you can get an idea of overall modulation density.

If you calibrate it to the scope graticules, you can even measure positive and negative mod percentage with some degree of accuracy.

Kind Regards,
David
 
Called TFT again the other day and talked to Daryl Parker. Nice fella, thanks for direction! He was able to answer my questions. I did ask about the lack of documentation on the TFT site. His answer was it would be to difficult to pdf the numerous drawings in the manual that are non standard in size. Hmmm.

Anyway I also asked him about the age of this unit circa 1990 and how the caps historically have held up. Funny enough he said he didn't feel the caps would be a problem.

Somewhat sceptical I ended up calling back later to tech support and asked the same qustion of them. Their answer was most definately the caps are probably shot. Estimate to replace caps and recal approx $1000.00. Ooch!!

Any opinions on this??? I'm leaning towards not worth it. Or is it even needed?
 
I know in my case I had a 700 series FM monitor that I had to recap (I bought it used and it basically went on fire when I plugged it in). It had uite a few shorted caps and only came back to life once I did a complete rehab. You have to ultimately decide if it's worth it to you.
 
cdkirk said:
Somewhat sceptical I ended up calling back later to tech support and asked the same qustion of them. Their answer was most definately the caps are probably shot. Estimate to replace caps and recal approx $1000.00. Ooch!!

Any opinions on this??? I'm leaning towards not worth it. Or is it even needed?
Click to expand...

There was a fellow in the back of Radio Guide or Radio World that advertised as J-squared or something like that. His work is pretty good, but keep in mind that it takes time to do that labor.

What you might want to consider is doing all the cap changes yourself, then let J-Squared do the alignment and tuneup. It might save you some money.

As for the PDFs on the their web site, they get a premium price for manuals. A model 724 manual I had to buy was $80. I doubt what you were told is a real issue.
 
Have decided to give up on the TFT box. Have been looking a little more at the Inovonics 531 unit and noticed that the Hi Level and Lo Level input both run through the internal tuner. Anybody have any opinions on this? The frequency agile units I've been around usually give you a direct (non tuner feed) on the Hi side. The RF levels at the Transmitter have always worried me about a tuner fed sample. Any opinions?
 
Perhaps the hi-level feed via the tuner is meant to be able to give you the ability to monitor multiple transmitters at a single site. I know Belar offers the DC-4, which is similar to their frequency agile RF amp, but only accepts a high level signal to allow this sort of operation. Maybe Inovonics is trying to do the same thing without making the broadcaster purchase an extra device?
 
J Squared will repair that 844 for about half what TFT wants to do the deed. Jim Jones and his techs do good work, so I would go with them for a repair. If you don't want to go that route, I'll buy the TFT from you and have Jim repair it and then use the monitor as a portable. I think they are great.
The Inovonics is a fairly good box, and works well enough that plus or minus 5% is what you can expect. If you really want to monitor peaks, though, you need to go to Belar and their FMMA-1 Wizard. I've not found any better accuracy anywhere. My favorite thing to do is use an analog and digital monitor, side by side. It provides the whole picture.
 
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