[462ron]

Hi all, I am ready to align the FM part of my Philco 52-944. I have done countless alignments before but this will be my first time doing an FM alignment. So, I realize I need a sweep generator and dug around and came across this TV sweep generator my dad built sometime in the 50s. I see it does cover the FM band and looks like I can align the IF and discriminator with it I hope. It has a 4.5 MHz crystal probably for the old TV sound IF alignment. I want to try and find FT-243 type crystals in 10.7 MHz and 9.1 MHz frequency that my Philco needs. Right now, I’m going through this Heathkit checking resistors, so far so good, and I’ve already replaced electrolytics. I really hope this sweep generator works out for me, we will see!

Ron    

[RodB]

Hi Ron, I've been doing FM alignment with just the 10.7 Mhz carrier from a signal generator and monitoring the AGC voltage. I found this method several years ago when restoring a 1960 Grundig. The alignment instructions were to use this method and are much simpler to follow. I'm guessing Grundig designers figured most techs wouldn't have an FM sweep generator. I get very good results.

[462ron]

Hi Rod, I kind of thought you could just use the IF frequency from my signal generator for most of the IF chain but Philco doesn’t show that procedure and recommends a sweep generator for getting the discriminator right. They give that procedure along with the curve you need to get for the least distortion so since I found my dad’s old sweep generator, I’m taking a side journey here and see if I can get it in operating condition and then try it on my Philco.

Ron

[Radioroslyn]

I'll bet if you're working on an early set w/a FM1000 you'll need a sweep generator to get it on the nose.

[RodB]

Good point Terry, forgot about the orphan.

[462ron]

No FM1000 in this set, it uses a 19V8. Still working on the sweep generator and it appears it oscillates according to my frequency counter. I may replace all the old output connectors on the front with BNC connectors so I can use modern cables for everything. My regular signal generator, frequency counter and oscilloscope all use BNC!

Ron

[462ron]

Well I went through this sweep generator and the sweep oscillator section is being problematic. With my frequency counter attached to the output I can see it is way off from the dial setting and isn’t stable at all. It jumps around in frequency and doesn’t settle down. There’s not a whole lot to the oscillator, all resistors are good and the few caps are disc ceramic types. I have changed them anyway but still the same. It uses what Heath says is a saturable reactor or increductor along with the tuning cap. The increductor is coated in tar which has cracked and flaked off in spots. I have one hope left and that is to get a new 6BQ7 oscillator tube and try that. If it’s that increductor then this will be only good as a door stop!

Ron

[462ron]

Well looks like the increductor is bad and is unobtanium sooo….i ve bid on and won an Eico 368 tv/fm sweep marker generator for a decent price. Fingers crossed it turns out to be useable!

Ron

[radiorich]

Hello Ron,
Sorry to hear about that bad part because that heathkit looked like a nice one .

I too need to get myself a sweep generator I have like 3 or 4 early Fm sets .

Sincerely Richard

[RodB]

I can't even pronounce increductor!

[462ron]

Rod, I had the same problem plus I’ve never heard of this component until I read the manual for this sweep generator!

Richard, yes this sweep generator is in excellent shape for being kicked around for probably 65 years or so. I’ve had it for 40 years in my attic which is freezing in winter and broiling hot in summer which I’m sure wasn’t good for it. Wish dad was still hear to ask him how well it worked when he used it!

Ron

[radiorich]

Hello Ron,
Yes , Attics are not the best place to store electronics !
I have late 1950s Heathkit scope that my friend's late father built when he was younger .



Sincerely Richard

[462ron]

Same here Richard. I have a few pieces of equipment my dad built from the 50s when he was in the repair business. A few pieces I have gone through and am using on my bench. I had his old Heathkit oscilloscope but sold it as it really wasn’t worth the time and expense to get it running as I have a couple of other more modern solid state scopes if you can call 1970s era modern   Anyway this sweep generator appears to have a bad increductor so I now have an Eico 368 sweep generator that I won for a decent price on eBay. I’m old school so I don’t understand digital terminology or equipment. I’m slowly going through this Eico before trying it out.

Ron

[462ron]

Getting back finally to my Heathkit sweep marker generator which appears to have a bad increductor. So I have since bought a Eico 368 generator. Part of the setup requires making what they call is broad band detector. It should be in a shielded box so I improvised with what I have. 

Ron            

[462ron]

OK, I need to rename this thread to say..Eico 368 TV/FM Sweep Generator instead of the current title..Heathkit Sweep Generator TS-4.. as I don’t know how to rename my thread. The reason being my Heathkit is dead in the water as it needs a part that is unobtanium! I am now working with my Eico 368.

So I have built the “broadband demodulator” as required (see last post above #14) and got the desired pattern they expect which is two parallel lines, my pattern also has the 10.7 MHz pip superimposed on top ( see attached last photo at bottom)). I have purchased a 9.1Mhz crystal to use for aligning my Philco 52-944 and also purchased a 10.7Mhz crystal for my Zenith 7H-920 I am currently working on.

The problem is when I I run the signal through the radio per Sam’s alignment procedure, I can get the pattern desired from the discriminator but there’s no 10.7 MHz pip on trace anywhere even though the crystal oscillator is dead on according to my frequency counter. See first photo below.

I have altered this generator by installing a switch so I can kill the sweep oscillator thus leaving me with an accurate IF signal. I used this crystal controlled signal to do a step by step alignment with no sweep and got the radio playing beautifully. I could leave well enough alone which I might do but I would really like to know why I can’t see the marker pip on the display. I’ve never done a sweep alignment on a FM radio so I don’t know what I’m doing wrong!

Ron