Need Clarification on Yamaha R-500 FM Alignment

[whirligig]

I'm in the middle of aligning this Yamaha R-500 and the service instructions threw me in a loop. In the attachments is a table outlining the adjustments to be made to the FM tuner and a diagram of the tuning locations. Where I'm confused is the #2 callout just above the adjustment table. It says 2. Perform this adjustment and a lowpass filter must be used. I don't have any detail what this lowpass filter is and where it should be used. Does anyone have a clue what is meant here?

Step 2 in the table under Adjustment method calls out for a Tuning meter. This Tuning meter appears in Step 2 Tracking adjustment 1 and Step 4 Discriminator balance.The only detail is shown in the tuning location diagram where the Tuning meter is attached to R168 and J161. I'm assuming this Tuning meter is a +/-100uA Galvanometer. Would that be correct?

In the diagram with adjustment points, there is an asterisk describing the tuning meter attachment. It says The tuning meter is to be connected to a circuit which include the Ji00088 or equivalent connected in series to a 47kOhm resistor. I can't find anything about the Ji00088. Any clue what that might be?

[bob91343]

My take on it is this:

The low pass filter needn't be hadware; just try to ignore the high frequencies on the scope screen.

The ji number may be the part number of the meter itself.

The bottom line here is to ignore the details and work with the adjustments and what they do.  Common sense applies; don't get befuddled by the specifics.  What you want is best dial calibration, lowest distortion, greatest sensitivity, and best separation.  You know where the controls are and what they do, so use your knowledge of how stereo works and go from there.

If your understanding is lacking, read up on it or enlist the help of a friend who can work with you.

[CaptDon]

Did someone screw up the alignment??? Do you have reason to believe it can be aligned for better performance than it is already giving? Do you have a very stable signal generator which can provide an accurate signal with pilot injection and so forth?? Chances are you may end up making it far worse with no way to get it right. Can your signal generator give you the choices of L, R, L+R, and L-R with the options of turning the pilot on and off for good mono summing and great stereo separation (which is never better than about 40db anyway). This is certainly not a job for a C.B.'er with a package of diddle sticks.
 

[whirligig]

My take on it is this:

The low pass filter needn't be hadware; just try to ignore the high frequencies on the scope screen.

The ji number may be the part number of the meter itself.

The bottom line here is to ignore the details and work with the adjustments and what they do.  Common sense applies; don't get befuddled by the specifics.  What you want is best dial calibration, lowest distortion, greatest sensitivity, and best separation.  You know where the controls are and what they do, so use your knowledge of how stereo works and go from there.

If your understanding is lacking, read up on it or enlist the help of a friend who can work with you.

I went back and compared the alignment instructions to my Luxman tuner which I did recently. The tuning meter is a galvanometer. I used one from work for the Luxman and it came out well. i think this time I'll just use the bar graph feature on my Fluke. I won't worry about the low pass filter then.

[whirligig]

Did someone screw up the alignment??? Do you have reason to believe it can be aligned for better performance than it is already giving? Do you have a very stable signal generator which can provide an accurate signal with pilot injection and so forth?? Chances are you may end up making it far worse with no way to get it right. Can your signal generator give you the choices of L, R, L+R, and L-R with the options of turning the pilot on and off for good mono summing and great stereo separation (which is never better than about 40db anyway). This is certainly not a job for a C.B.'er with a package of diddle sticks.

I found this Yamaha maybe 15 years ago on the curb with a bunch of other electronics. There were cold solder joints on the amplifier IC from thermal cycling and so it wasn't working until I reflowed the connections. The tuner performance was disappointing and so I shelved it for 15 years. Recently I decided to restore it. I got rid of the corrosive glue, recapped it, removed the amp and driver IC's and resoldered it, checked many of the diodes and transistors, and repaired the 5V regulated power supply which caused several old 6.3V electrolytics to overheat when it failed. The receiver performance improved but the dial is off and the sensitivity and selectivity could be improved. Yes, it needs an alignment. It'll be the second time I'll use my Danish made Radio Technology RE125 Rf generator that I recently purchased. Some of the lingo on this generator is a little different but the major parameters are there e.g. Rf frequency, signal level in several units, toggle and set the pilot, deviation, modulation on the L & R, etc. This baby is more signal generator than the HP or Boonton I use at work. Unfortunately it's just as big but heavier.

So forgive me, this ME is still learning.

73

[CaptDon]

Sounds like a nice signal generator with all the features you need for proper alignment. I worked as a Chief Engineer for the FM portion of an AM/FM outlet in York Pennsylvania. The studio site used Orban and Time Frequency Technology gear to get the signal up to the mountain. On the mountaintop we had a 5kw CCA transmitter for hot standby and a 20kw CSI running 11kw into the feedline with about 6kw arriving at the antenna for 50kw ERP. The tower was 400+ feet from the transmitter building and the antenna was 820 feet up. I would tune the transmitter for a flat bandpass to remove as much AM component as possible. This was not the most efficient operating point because things were not at their peak of resonance. CSI data registered with the FCC claimed 73% efficiency but we seldom got better than 69-70%. The exciter was a BE20 if I remember correctly. The IPA was the 5CX1500 with the A version and the B version used but they were all crap!! Prone to all kinds of failures and short life. The emission would start to drop rapidly at about 8 months even with careful use of filament voltage control. They were also prone to silver migration along the ceramic between the plate and grounded G3 ring which lead to arcing and the ceramic cracking. Probably the worst design from Eimac ever with the possible exception of the 'more expensive than gold' 4CX600 series (JA, JB) built for the military at military pricing!!

[whirligig]

Sounds like a nice signal generator with all the features you need for proper alignment.

Yes, it is. It'll even do RDS which is something I'll probably never deal with. Most of the things I have pre-date RDS except for the MP3 players with FM radios. But, those are disposable since there isn't anything that can be tweaked.

I worked as a Chief Engineer for the FM portion of an AM/FM outlet in York Pennsylvania. The studio site used Orban and Time Frequency Technology gear to get the signal up to the mountain. On the mountaintop we had a 5kw CCA transmitter for hot standby and a 20kw CSI running 11kw into the feedline with about 6kw arriving at the antenna for 50kw ERP. The tower was 400+ feet from the transmitter building and the antenna was 820 feet up. I would tune the transmitter for a flat bandpass to remove as much AM component as possible. This was not the most efficient operating point because things were not at their peak of resonance. CSI data registered with the FCC claimed 73% efficiency but we seldom got better than 69-70%. The exciter was a BE20 if I remember correctly. The IPA was the 5CX1500 with the A version and the B version used but they were all crap!! Prone to all kinds of failures and short life. The emission would start to drop rapidly at about 8 months even with careful use of filament voltage control. They were also prone to silver migration along the ceramic between the plate and grounded G3 ring which lead to arcing and the ceramic cracking. Probably the worst design from Eimac ever with the possible exception of the 'more expensive than gold' 4CX600 series (JA, JB) built for the military at military pricing!!

Oh man, you really worked with some high powered stuff! The most I ever see is 300W coming out of a Drake or Swan transceiver at work as a radio tech. Your experiences has brought back some memories as a young ME packaging antenna farms on satellites. It was all about getting maximum EIRP on the ground. Everything from optimizing the locations of the TWT's and SSPA's on the payload to squeezing the largest antenna on a volume constrained spacecraft. The technical challenges sure made it an interesting job.

So you have 11kw coming out of the CSI and 6kw arriving at the antenna. Were these ohmic losses in the transmission line?

On the output tubes, at least you can bring down the transmitter and replace them. We had a similar situation where tin was in our supply line. The tin would develop whiskers. This shorted out several of our satellites crippled or dead. The first instance was a PanAmSat and it brought down telecom across CONUS. The day the earth stood still for us.

[CaptDon]

I would say that a portion of the loss was surely ohmic. 1220 feet of feedline. But also the dielectric losses in the spiral teflon insulator/spacer material. We ran dry nitrogen at about 1.5psi in the line and our worst enemy was pissed off hunters shooting the feedline where it ran up the Ch. 43 T.V. broadcast tower. The T.V. feed was waveguide that I would estimate at about 8" by 16" rectangular. Our FM was at 103.3Mhz and the AM was 910Khz at 6.1kw into the phasor cabinet sent to a 4 tower directional array. At one point we had 4 engineers on staff and we are all hams (I kept my advanced because it is a unique 2X2 call not issued anymore). I also worked for Jim Strauss K3JFL the owner of J.R.S. Distributors. We were a ham radio equipment dealer in York Pa attending nearly every hamfest in a 100 mile radius. Fun times!!! I am retired now, still living in the U.S.A. and still Company Senior Master Captain (Skipstjori in Icelandic). In fact we moved the boat to winter berth this very day!! Directly across the Bayfront from Hamot Hospital in Erie Pa. Cheers!!! 73