Ok. Let’s try this again…RCA 9TC240 Alignment

[Chris K]

After a couple weeks of false starts, equipment changes, troubleshooting and almost throwing several hundred dollars in vintage test equipment across the room I finally have, hopefully, a working combo of the three essentials to do this. A working trio of HP equipment: HP 8600 marker/HP 8601 sweeper generator and an HP oscilloscope rated at 100MHZ

If my friends who tried to help me with this before would like to hop back on board, maybe we can have a do over and try to see if I can follow discussions, theory and perform the hands on tasks resulting in finally…FINALLY seeing some alignment trace shapes on my scope. I’ll be working on the bench tomorrow after 1pm eastern daylight time setting some preliminary checks up. I appreciate all the input, time, knowledge and brainstorming provided in the previous thread. Thanks all!
Chris

[Penthode]

So you have the working pair on hand? That is terrific.

Once the equipment is confirmed working and the interconnection cabling is in place, the use of the HP equipment will follow the published alignment documentation. The RCA split sound receiver alignments always begins with the sound IF and Sound discriminator alignment because the proper Video IF alignment is dependent upon the sound aligned first.

[Chris K]

I confirmed frequency adjustments work but after moving on and trying the setup for the sweep characteristics setup, I'm getting nonsense on my scope. I think, the issue is my lack of knowledge on this HP 64600B oscilloscope. Most of my oscilloscope use is limited to hooking up a probe in a circuit, pressing "Auto" and comparing what my trace looks like as compared to what's in the service manual.

[bandersen]

It must be in XY mode. You cannot use the "auto" button. This is where a cheap, basic analog scope is easier to use. You do not need high bandwidth at all.

[Chris K]

I have it in XY mode. I can see the markers and move them but I’m not sure what this is supposed to look like. It’s a function confirmation protocol. Anyway, I think if I move straight to production of the sound discriminator wave and the 21.25 symmetrical trace for the sound IF, with help, I’ll probably learn more than I would going through all the tests. I’ve been in contact with the seller and after many email exchanges I’m confident in his statement the sweep generator works accurately.

[Penthode]

Can you show some photos? of the Scope setting, the setting on the 8601a generator, the settings on the 8600a marker?

I am particularly curious what yiou have on the display to start so we may guide you in.

[Chris K]

The cables and the sweep characteristics test are setup the way it is pictured in the manual on page 4-3. I put together the RF detector as you sketched out. There are two blanking inputs on the back of the marker generator so I plugged it into the one on the bottom...hey, I flipped a coin. They don't specify an RF frequency, only that the range selector be set as shown. At least the trace on the scope looks like a CRT! The tall, vertical line is the marker at approx. 106MHz on the counter but I don't think this sweep test is supposed to look like this, is it? My scope is set for XY input.

[Chris K]

...and I assumed the ground hookups to the RF out and Y scope input on your RF detector schematic is the line on the bottom and the signal goes through the 1000pf cap and the diode etc?

[Penthode]

The first thing I see is the sweep is set to full. That is the full bandwidth from 1.0MHz to 110MHz when the range is set to 110. To sweep across the center frequency indicated in the read out. Refer to page 3-2 in the manual.

Nest set the Sym Sweep with to 1.0MHz for aligning the sound IF and discriminator and fully clockwise to to the Video IF alignment.

Set the dial indicator to 21.25MHz to do the sound alignment and about 44MHz to do the Video IF alignment.

I generally use line truggering (lower left). On the 8600a the center button depressed for scope is correct for the sweep alignment. You press the CW when the generator is in CW to generate and measure the frequency of a fixed CW signal.

The scope I cannot see the settings but as Banderson indicated it must be in X-Y mode.

[Penthode]

When it is working correctly, with the test detector, you should see a flat line. When you select a marker button, then rotate the control, you should see a bright marker dot move along the line. The marker display will indicate the exact frequency of the marker at that point. I typically set as you see from my CT-100 IF response, to have the 5 markers from left to right across the the response.

Are you inserting the detector circuit?

[Penthode]

I switched on my 8601a, 8600a and the scope. I left the RF out to the scope Y input disconnected. The scope is in X-Y mode. The generator is set for a 3MHz sweep width across 50MHz. So it is sweeping from 48.5 MHz to 51.5MHz with 50.0MHz in the middle.

I set the markers across the band being swept with the center button of the marker selected and set to 49.99MHz. You will see it in the middle of the scope display as the brightest marker because the marker button is depressed.

You should see this BEFORE connected the RF.

Also a correction to my earlier instructions: Put the sweep trigger switch (lower left) to FREE. It eliminates the bright dot on the right which I believe is due to the sweep waiting for the next line trigger. Fee run is fine so long as the swwep speed when aligning is not set too high. (we can discuss that later when you get to that step).

[Chris K]

Yes it’s in there. For the test of sweep characteristics. I’ll look at your instructions and work on it. It’s Bedtime for Bonzo right now. Talk with u tomorrow!!

[Chris K]

I’m putting the HP manual aside and just following your instructions to the letter from now on! I’ll be able to do more on this tomorrow evening and most of the day Tuesday. I’ll be “working from home “ Tuesday!

[Chris K]

Questions...

What is sitting on top of your counter? Is that something I need?

How are the cables connected between the sweep/generator and the counter? Forget the scope right now. I have everything disconnected to start from scratch.

[Chris K]

So far, all I have hooked up is the cable to the aux out of the 8601