Alignment Tools?

[super98lsc]

Ok so my fluke 87 true RMS which is about 12-14 years old now I think should do this function fine then. I was trying to figure out how on earth an old mechanical tube meter could superior to a modern high end one. Not knocking on the old stuff but seems they would not "lose" functionally in 50 years of R&D.

Have a few beginner questions...

When the manual says connect o-scope to Output Load. Which output are they referencing?

Also the IG-37 RF output is centered on 100hz. Shouldn't it "broadcast" on other frequencies as well? Example in the sansui instructions they want you to tune the dial to 90/106 and some other spots for different steps. I'm thinking I need to go through the IG again and be certain someone didn't remove or setup something inside into a calibration mode and left it there electrically speaking.

 

[ConradH]

Usually you look at the signal at the speaker outputs or the tape outputs when doing most adjustments other than IF. I've got a write -up on the 2000x on my web site, and I added alignment info at the very end. The service manual has some errors and the 2000x will have loops on the bottom of the PCB where you measure, not the test points listed in the manual. There's also a write-up on the Yamaha CR-620 alignment that has some good general info you might use. The big difference between the two is that the 2000x has tuned transformers in the IF, whereas the CR-620 uses ceramic filters- no IF adjustment needed.

My LSG is also centered at 100 MHz and I think that's common for an MPX generator. They weren't intended for dial calibration. For dial calibration I use the 8640B, but you can actually do it with broadcast stations if you have some near the ends and know their frequency. It can be harder because unlike the generator's obvious tone, you may not immediately know what station you're listening to. The method is best if things are already close. That's the reason I have several generators for the different purposes. Naturally more $$ will get you every possible thing in one generator.

 

[super98lsc]

Excellent thanks again guys. The manual also stated to connect my scope and or generstor "via the 10pF cap" since I don't see a 10pF cap I presume it means to couple my equipment using that.

On the IG- mine is only variable +/- 2MHz on either side of 100MHz. Which is part of the instructions in the assembly manual for centering the RF portion of it. Makes me think something isn't quite where I need it yet. I'll read and play more with it later today.

 

[rcs16]

In older SM, they called out a VTVM, for it's high Z and bandwidth, which usually implied a HP 400 series meter that used a nuvistor tube in the front end, so technically it was a VTVM, the rest of the circuitry was semis. There is also the HP3400A true rms voltmeter. It is the 100KHz-10MHz region were VTVMs are most useful and accuracy trumps many semi based meters.
My HP 3478A does about everything a VTVM will do, with precision.
For peaking RF tuned circuits, analog is so much easier on the eyes than digital.

rBuckner, I certainly would like a copy of that panasonic sm, if you do not mind.

super... I understand it as, you are to supply the cap, to block DC, what procedure are you refer too?

thx
Rick

 

[ConradH]

Very often signals and measuring equipment are coupled to the circuit through a very small cap, 5-10 pF. This prevents loading and pulling of the frequency. Hint- twist a couple pieces of insulated wire together about 5-10 times and you have a poor man's 10 pF cap.

 

[gadget73]

In the prehistoric days of radio, when small value caps did not exist, these were called "gimmick" capacitors. It was exactly what Conrad described, a couple insulated wires twisted together a few times. Looks like some sort of rigged nonsense but it worked.

 

[rBuckner]

...rBuckner, I certainly would like a copy of that panasonic sm, if you do not mind.

...

Sure, shoot me a PM with an e-mail address and I'll get it to you.

 

[super98lsc]

Thanks again everyone. You guys have been a huge help. Funny how this "old tech" is such a lost art and more complex than most can imagine. Taken for granted these days. I remember the days of " wow you have a "transistor radio" and it received FM Stereo! That was the coolest thing ever when I was a kid. Back then DJ's talked about the music, the artist, and bam cued the songs in a way you could tape them nice and clean for later enjoyment. Now......

 

[super98lsc]

From the IG-37 assembly/operation manual. This would mean that it only broadcasts centered on 100MHz +/- 2MHz. So when I am following the Sansui alignment procedure they call for tuning the dial to 90 and 106. Does that mean this unit wont do me any good since its fixated on 100MHz?


SPECIFICATIONS

RF Signal Output Center Frequency……………. 100 MHz adjustable by approximately
±2 MHz.

Pilot Modulating Frequency. ………………........ 19 kHz ±2 Hz.

FM Modulation. ………………………………………….. Left channel (stereo).
Right channel (stereo).
Phase test (left plus right channel in phase).
Monophonic FM

Deviation……………………………………………….. Adjustable to 75 kHz.

Sweep Rate. ………….. 60 HZ

Sweep Width.---------------------- Adjustable to 750 kHz.

RF' Attenuator Range.----------------------- 60 db in 20 db steps.

Crystal-Controlled Markers.

• 10.7 MHz.
• 90.95 MHz.
• 96.30 MHz.
• 101.65 MHz.
• 107.00 MHz.

Composite Signal Output:

• Left channel (stereo).
• Right channel (stereo),
• Phase test (left plus right channels, in phase).

 

[rcs16]

I have not read the manual, but it looks like it does a few functions
1) Provides a 100MHz carrier modulated at up to 75KHz deviation with optional stereo modulation. Use this for IF alignment, FM detector distortion, stereo demod. alignment
2) Provides a sweeper function (the clue is the sweep rate) with markers. Use this for older IF strips "10.7MHz marker/sweeper" that uses L/C tuned ckts (set for critical damping of lumped L/C stages) and to center the "S" curve in the FM detector.
Can also use it for RF tuned ckt alignment. Need to use the sweeper rate as input to the "X" horizontal input on the scope. On the "Y" axis, use the detected RF level. Where to pick off, the signal or agc detector?. I guess you can use this method to peak the tuned circuits for maximum vertical deflection as they ask for "alignment procedure they call for tuning the dial to 90 and 106." The marks show you where the important band points are located on the horizontal sweep.A t one end of the var cap you peak the coils and at the other end you peak the trimmers on each var cap gang.
I have never done this, anyone else? give it a shot.
So you need to have both ends of the FM band, so that you can align the tracking of the L/C tuned circuits in the front end.
Good luck with my blurb!! You be the judge if it makes sense.
Cheers
Rick

 

[super98lsc]

Rick,
Makes great sense actually.

Had I think decent luck at the Surplus Auction today! Ill know when I get it all home cleaned and tested out. But here is my shopping list.

• HP5238A - 500MHz Universal Counter - This should do the trick for anything I need??
  
• Tektronix TYPE 191 Constant Amplitude Signal Generator- 350kHz to 100MHz
  It appears to be in good shape and did not have any "warning-inop" stickers on it. Figured since its from 1969 and has 7119 tubes in it, I will bring it up slow on the variac and test it out after cleaning.
  
• Tektronix 2445 150MHz O-Scope
  Looks to be decent shape with all the leads, cords, multiple probes, still in the original matching bag on the top. Just needs a thorough cleaning.
  
• I got Tektronix matching Scope/Equipment rolling cart. This will be nice to have everything racked up on

Hopefully the testing and cleaning and operations of all 3 devices work out for me.

 

[rcs16]

All good finds!!
HP 5328A, good one, does it have a 10MHz oven? I used these before and have a printed service manual. You have the 500MHz pre-scaler too. I have 2 of 5316A, little newer than 5328A, with a 1GHz pre-scaler.
Tektronix TYPE 191 Constant Amplitude Signal Generator- 350kHz to 100MHz. Not sure what the heck you can use this for, scope cal, flatness tests?
tek 2445, another good find. I used to use a 2467, the 400MHZ big bro. What probes did you get?

I started reading the IG-37 manual, look at page 41, it explains what it is used for. I was close in my explanation. I have to study the design a bit more. i think that you should be able to replace c22 (6.2pF) with a air gap tuning cap, from a old stereo LO. May even use a varactor diode and use DCV to reverse bias thus tune the oscillator. Now that you have a counter, makes life so much easier. Hi-voltage stuff is a bit scary, I am used to 3.3V (logic level stuff)
This generator is 300 ohm balanced o/p, so if you want to use it for 75 ohm, you need to use a balun.

 

[rBuckner]

Some nice grabs there super98!

 

[super98lsc]

Yah I wasn't certain on the 191 either but for 10 bucks I figured why not. The scope won't give a trace of any kind on any of its 4 channels. It lights up runs through the selections and such. Screen is a bit worn, even focused its not super sharp so figure the CRT has seen better days also.

Haven't opened it up or bothered with it much yet. The counter is dead nuts accurate.
Not bad for $50.00 overall got the cart, counter, and the spare scope and 191.

 

[super98lsc]

Oh the freq counter was just calibrated this mid this year. How do I find out which oven it has?
Leads- Tektronix (4)P6131 and (1)P6122 and (1) random M-12
Few spare BNC connectors and 1 spare attenuator module for a Tek 2465 scope. And a few bags of random never used transistors rofl.

 

[ConradH]

That IG-37 has crystal controlled markers. Can't those be used to set the dial calibration? Why else would they be there?

 

[super98lsc]

That's what I was thinking as well.

 

[rcs16]

HP 5328A option 010, has A3 oscillator support board for 10MHz oven oscillator 10544A. If does not have the oven option, it a standard crystal osc, with no temp stabilization.
Options are printed on labels placed on the back. You have option 030, channel "C" 5-512MHz, 15mV sensitivity.
This model was our factory cal standard at Motorola back in '85
Too bad about the 2445. Scopes are fun to fix, need a scope to fix a scope

 

[transmaster]

Wow I came here to ask about a good set of Alignment Tools, and there was already a thread going. Both of My solid state Zenith Trans-Oceanic radio the Royal 1000, and 7000 need alignment, especially the 1000. I need a better set of alignment tools. These T-O's have hex keyed tuning slugs and none of the ones I have fit. It is time for a new set. What would you suggest?

 

[rBuckner]

I use the Aven Tools set, I think I got it at DigiKey. Kit number 13-016. They are anti-static to boot! Still, once you sit down to do an alignment touch the tuner housing to discharge any static. Don't want to blast any front end FETs!