RCA 9TC240 Alignment...The start of my education (I hope!)

[Chris K]

Originally Posted by bandersen

1077 is not an alignment generator or fixed frequency RF generator - it only outputs test patterns. Composite or RF modulated video.

Yes yes yes yes yes....I shouldn't talk about these things without them in front of me...I meant the 415...I have them both.

[Penthode]

I bought my HP 606B locally thru Facebook Marketplace for $35. It required some repair. But to obtain the accuracy with it or any other marker source, you will require a frequency counter.

Decent sweep generators are easy to find cheaply. Coupling the equipment should be straight forward if you follow the procedure outlined.

You will be able to get the responses depicted only if you have the proper equipment and you can trust your frequency source.

And I only ended up with the HP606B because it was cheap and available. I have have three different HP frequency counters which I obtained over time because they happened to be cheap and were readily available. I believe we live in a fortunate time where so much 1960s and 1970s test equipment which we once could only dream of are now available for next to nothing.

What have you to measure the frequency source accurately?

[Penthode]

I want to reluctantly add that I have not be averse to dumpster diving. A local community college was throwing away Wavetek sweep marker generators. The cords were cut off and a few toggle switches were faulty. All easily fixed and it was free. I earlier used an old Precision generator made in Elmhurst NY which I got for free. It needed a few repairs but it worked well. The venerable HP5245L I bought for $25 with a few minor faults. The best addition I made to it was to replace the noisy original fan with a quiet modern computer fan.

I would suggest you first present here your equipment choices and we can provide advice.

[Chris K]

Hi all...just a couple of things and questions.

I did the first two steps in the alignment that required the use of the VTVM and I think I was successful.

So yes Penthode, I will detail a list of the equipment I have. Below is what I bought, restored and thought would provide the entire package for doing these alignments.



The way I understood this worked was the RF frequency out is selected using the dial on the right. You select signal strength with the attenuator dials. Sweep width is selected using the sweep dial. Maximum range on this is 10 megacycles. The signal is fed into the desired point(s) on the chassis. If the signal out requires demodulation, it comes back in from the desired point in the circuit using the demodulation cable back into the 369. At that point, a marker is added to the trace selected by the dial on the left and the marker size is adjustable. The processed signal comes out and goes to the scope by the scope out jack which is a funky, special jack that essentially provides a horizontal, vertical and ground signal interpreted on a scope using X-Y mode.

Here are my oscilloscopes...an HP 54600B and a Chinese scope...works well and cost a little over $200 (not that it indicates anything. It was well reviewed)





That's what I got! I don't have a frequency counter or a separate RF generator and sweep generator. I think I have a shelf full of equipment that needs to be scrapped and I'll have to start from scratch!


Some of this has already been done but if my friends can provide some shopping lists and maybe some information on how all of them work together it would be appreciated. I think, at this point, I don't have what I need to dive into the more detailed and intricate steps in this process.

[Electronic M]

Originally Posted by bandersen

1077 is not an alignment generator or fixed frequency RF generator - it only outputs test patterns. Composite or RF modulated video.

+1 the 1077 is for figuring out WHY your IF is dead, not for alignment....It's also good for signal injection troubleshooting on every other circuit in a TV (which is why I like mine it helps me fix dead sets faster).

[Chris K]

It’s a 4.5 mc. I have some pictures of pages from the user manual I can post in a bit

[Chris K]

For your reading enjoyment... Actually, I don't expect anyone to read all of this. My only hope is I can somehow use this piece of equipment to do some of the things, starting with the audio IF, I can do to optimize it's function.





























[img]

[Penthode]

I skimmed through the instructions and it is pretty standard stuff. The 4.5MHz crystal was intended mainly for later intercarrier sets which this is not. It has little use in this alignment other than perhaps using a harmonic as a reference to set the variable marker frequency. I have to emphasize that a split sound set alignment, especially this chassis, is somewhat more complicated than the average intercarrier set and an accurate marker is essential.

The 4.5MHz crystal oscillator has a useful 5th harmonic at 22.5MHz and 6th harmonic at 27.0 MHz. These would be useful as a reference for calibrating the variable marker.

The bottom line is that you can use the Eico but it is going to be more difficult to use that a more modern set up. Good equipment is relatively cheap. My first suggestion would be try the Eico sweeper and find a separate RF generator and a frequency counter to obtain an accurate marker. A separate marker oscillator can be loosely coupled. You can also use the separate accurate marker to calibrate the Eico marker.

For my IF alignment the HP 8600a Digital Marker with the HP 8601a Sweeper is one of the best setups. The equipment dates from the 60's and 70's and provides five accurate bandpass markers. I bought them twenty years ago for about $40 each on eBay. The HP8601a is common: there are about six on eBay at the moment but the lowest price is about $165. The HP8600a was it's companion and is to integrated with the HP8601a for accurate markers and spot frequencies.

The pair of HP devices essentially is an RF Network Analyser. I do not know how much you are into electronics but a more modern and efficient approach (and cheaper too) is to you to use a modern RF network analysis tool. I see Chinese built ones on eBay for under $50 and with client software on a computer I would see this as a very accurate and spiffy way to align your set. I have for the last decade seen the cost drop and performance improve. I haven't tried this solution out myself but you should be able to see the trap notches and IF and tuner RF responses very clearly and accurately with this device. This thread has kindled my interest to finally buy one these things to try out in the application.
https://www.ebay.com/itm/126284122318

[Penthode]

Here is another nifty one with a display. You should be able to see the IF response and accurately set the traps with one of these. I haven't tried it yet. But rather than using old clunky equipment, this may be the most efficient and yet least costly way to go.

https://www.amazon.com/Portable-Tiny...s%2C241&sr=8-4

[Chris K]

Originally Posted by Penthode

Here is another nifty one with a display. You should be able to see the IF response and accurately set the traps with one of these. I haven't tried it yet. But rather than using old clunky equipment, this may be the most efficient and yet least costly way to go.

https://www.amazon.com/Portable-Tiny...s%2C241&sr=8-4

I bought it. Maybe when it gets here we can take a shot at doing this together?

[bandersen]

I made a video on using the TinySA as a sweep gen for TV alignment. I think you'll find it useful.
https://youtu.be/BQJjgpHyWRs

[Chris K]

Looks like it can be used in conjunction with a separate tracking generator

[bandersen]

It is the tracking generator. I think you mean marker generator. Yes, you can loosely couple a second generator to create a marker blip

[Penthode]

Originally Posted by bandersen

It is the tracking generator. I think you mean marker generator. Yes, you can loosely couple a second generator to create a marker blip

Great to see you had the Tiny SA. You were highlighting my fear as it only would examine RF spectrum. It is not what I would call a network analyser since it does not have a sweep source that tracks with the spectrum analyser display.

The WinWT4 Spectrum Analyzer RF Signal Generator With Tracking Generator appears to be more appropriate and is cheaper too! It has a tracking generator output which is fed to the device under test, in this case the input to the IF amplifier. The output is applied to the RF input of the Spectrum analyser. Then you use the the software to provide the display of the sweep on a computer. No need for an oscilloscope.

Here is the link again:

https://www.ebay.com/itm/126284122318

[Chris K]

Originally Posted by Penthode

Great to see you had the Tiny SA. You were highlighting my fear as it only would examine RF spectrum. It is not what I would call a network analyser since it does not have a sweep source that tracks with the spectrum analyser display.

The WinWT4 Spectrum Analyzer RF Signal Generator With Tracking Generator appears to be more appropriate and is cheaper too! It has a tracking generator output which is fed to the device under test, in this case the input to the IF amplifier. The output is applied to the RF input of the Spectrum analyser. Then you use the the software to provide the display of the sweep on a computer. No need for an oscilloscope.

Here is the link again:

https://www.ebay.com/itm/126284122318

Yes I looked at these in some detail last night. It's worth a shot, even just as a product review for everyone to comment on. The cheapest option isn't necessarily a requirement as I'd gladly spend up to $400 or so for a good quality instrument. I believe these are manufactured and shipped from China so I imagine QA might be an issue and shipping may take several weeks to get to me. I'll order one and we can use it when it arrives but I'm still open to other suggestions even if they are more expensive options.