Kenwood KT-3300d Alignment Question

[kenwoodm2a]

So I started checking the alignment of my Kenwwod KT-3300D tuner.
I'm practicing on my spare unit first to make sure everything goes ok and I have marked off all pots and coils with a sharpie just to make sure.

For the most part, everything so far is going good and I can see actual changes in my adjustments on the scope, distortion meter and ac/dc meter.

On the alignment sheet that I attached to this post, items 5, 6, and 7 are causing me some grief as I can't seem to notice any changes on my scope when making adjustments which is leading me to think that perhaps I'm doing something wrong.
Attached is a picture of my scope display showing the 1 kHz output at the RCA outs as per the alignment procedure.

Can anybody explain why any changes to the coils are not affecting my output reading?

One thing I will mention is that on the 3rd attached alignment page, it shows a picture of a 300 to 75 ohm antenna adapter and what they call a dummy antenna. I'm not sure what a dummy antenna is but what I did is I gutted the 300 to 75 ohm adapter and connected the center pin direct to one of the screws and the outer ground shield direct to the other screw which is connected to a 50 to 75 ohm resistive pad to the generator. I assume that would be the correct way to do this?

Thanks!

 

[rcs16]

Use the THD meter (distortion analyzer) as they show to do any distortion adjustments. You can not use a scope as your eye can not determine THD on a sine wave accurately.
Can use the scope in conjunction with the AC voltmeter to peak coils in the front end and IF.
If your RF sig gen has 75 ohm o/p, connect that directly to the tuners 75 ohm input using 75 ohm coax.

 

[Punker X]

Reduce your signal generator output. You have it 100 units.. can tell what your setting is.. dbu or something.. Wayt to high to align the front end.. One way to do with just the generator and scope is to reduce the signal down until you see noise and adjust for reduction in noise, on a digital tuner with LED signal meters is harder to peak than one with analog meters. You can reduce your generator down to where an LED just turn off and tweak until it lights then readjust your generator output.

Doesn't look like your generator has MPX capability. Will make things difficult to finish the alignment.

Recently did a KT-3300D. Might be one of the best digital tuners I've ever had come across my bench. It's also pretty complicated. Not the ideal learning tuner.

 

[kenwoodm2a]

Use the THD meter (distortion analyzer) as they show to do any distortion adjustments. You can not use a scope as your eye can not determine THD on a sine wave accurately.
Can use the scope in conjunction with the AC voltmeter to peak coils in the front end and IF.
If your RF sig gen has 75 ohm o/p, connect that directly to the tuners 75 ohm input using 75 ohm coax.

I have used the distortion meter on most of the adjustments that require minimum distortion setting but still have a couple more to do .
My generator is 50 ohm output which is why I made the 50 to 75 ohm resistive load pad

 

[kenwoodm2a]

Reduce your signal generator output. You have it 100 units.. can tell what your setting is.. dbu or something.. Wayt to high to align the front end.. One way to do with just the generator and scope is to reduce the signal down until you see noise and adjust for reduction in noise, on a digital tuner with LED signal meters is harder to peak than one with analog meters. You can reduce your generator down to where an LED just turn off and tweak until it lights then readjust your generator output.

Doesn't look like your generator has MPX capability. Will make things difficult to finish the alignment.

Recently did a KT-3300D. Might be one of the best digital tuners I've ever had come across my bench. It's also pretty complicated. Not the ideal learning tuner.

Yes, your right, my generator output is showing high in that picture but even at 80 it was still the same on the scope . Oh, and that output reading is in dbu emf.
I will try lowering till I see noise and try again . I assume that I start at the antenna input?

As far as my generator having MPX capabilities, it does have Main, Left, Right, and Sub as well as the stereo and pilot buttons so I assume that's what your asking? I was able to do most of the adjustments but still have a few left to do.

One thing I'm curious about.
If the generator and tuner setting is 98 mHz, and - setting the front end for maximum value at that frequency, wouldn't that imply that any channels that are tuned above or below 98 mHz would not be maximized? So if I only listen to one channel, say 103.9, wouldn't it be better for me to fine tune at that frequency?

You mention that you recently tuned one of these tuners. Yes, you are correct in saying that this tuner
Is complicated but seeing that I'm practising on my spare unit, if I can figure this one out, then the rest should be easier....I hope!

Did I make the correct kind of connection from my generator to the tuner with the resistive 50 to 75 ohm matching pad and the antenna adaptor being gutted as described in my first post?

Thanks!

 

[Punker X]

but even at 80

You need to take it down to about 35 to 15 to see a change

setting is 98 mHz

Step 5 peak coils at 90Mhz
Step 6 Peak trim caps at 106Mhz
98Mhz for IF. Doesn't matter where you are tuned to really the IF frequency is 10.7Mhz. Most tuners call for 98Mhz, but could really be any frequency.

 

[rcs16]

I was taught as a tech at Motorola to adjust the front ends by measuring and adjusting for the best quieting sensitivity. Monitor the noise thru some speakers and the null on the AC voltmeter. Keep reducing the RF level so you get down to the noise floor.
The IF coils should be peaked and then fine tuned for best mono THD after the discriminator is zero'd and fine tuned for best THD, these can be interactive so best to go over them a few times.
I bought a mini-circuits 50:75 ohm pad on ebay, this part should be well shielded.

 

[kenwoodm2a]

You need to take it down to about 35 to 15 to see a change



Step 5 peak coils at 90Mhz
Step 6 Peak trim caps at 106Mhz
98Mhz for IF. Doesn't matter where you are tuned to really the IF frequency is 10.7Mhz. Most tuners call for 98Mhz, but could really be any frequency.

OK, I will give it a try again at a lower output setting till I see noise and see if I notice any changes.

Should I start at the antenna input coil and move ahead from there?

Hopefully once I figure this tuner out I will move on to my other tuners......KT-5020 and my Model Eleven GX

Thanks for your help!

 

[kenwoodm2a]

I was taught as a tech at Motorola to adjust the front ends by measuring and adjusting for the best quieting sensitivity. Monitor the noise thru some speakers and the null on the AC voltmeter. Keep reducing the RF level so you get down to the noise floor.
The IF coils should be peaked and then fine tuned for best mono THD after the discriminator is zero'd and fine tuned for best THD, these can be interactive so best to go over them a few times.
I bought a mini-circuits 50:75 ohm pad on ebay, this part should be well shielded.

Thanks for the info! Every bit counts!
I'm gathering up as much expert knowledge as I can to succeed with my alignments .

 

[rcs16]

Most procedures have you start with the low end, 88MHz, adj coils starting with the ant input coil and then proceeding down the stream. Then go to 108Mhz and adjust the trimmer caps. back to 88 Mhz and check for interactions.
In many digital tuners you adjust the LO VCO coil first, set it for a specific tuning line DCV, usually the high end first then check the Vt at the bottom of the band.

 

[Bob@FM]

OK, I will give it a try again at a lower output setting till I see noise and see if I notice any changes.

Should I start at the antenna input coil and move ahead from there?

Yes, peak all the coils, except don't touch the local oscillator coil (usually the opposite end of RF strip from the antenna coil). Be aware that the antenna coil and trimcap is usually not very responsive to small adjustments. On those it can take large gross adjustments to see movement. As others said, do this with signal level so low it shows some noise on the audio out mono signal. Also make sure the audio signal sine wave on scope is symmetric, not uneven between top/bottom.
After you do the RF once, do the IF coils/detector, then do the RF again, etc. Do this loop until no improvement is found. If the signal gets less noisy on the scope, lower the RF level.

 

[kenwoodm2a]

Most procedures have you start with the low end, 88MHz, adj coils starting with the ant input coil and then proceeding down the stream. Then go to 108Mhz and adjust the trimmer caps. back to 88 Mhz and check for interactions.
In many digital tuners you adjust the LO VCO coil first, set it for a specific tuning line DCV, usually the high end first then check the Vt at the bottom of the band.

Thanks again for that added info!

 

[kenwoodm2a]

Yes, peak all the coils, except don't touch the local oscillator coil (usually the opposite end of RF strip from the antenna coil). Be aware that the antenna coil and trimcap is usually not very responsive to small adjustments. On those it can take large gross adjustments to see movement. As others said, do this with signal level so low it shows some noise on the audio out mono signal. Also make sure the audio signal sine wave on scope is symmetric, not uneven between top/bottom.
After you do the RF once, do the IF coils/detector, then do the RF again, etc. Do this loop until no improvement is found. If the signal gets less noisy on the scope, lower the RF level.

Thanks Bob! Everything you describe about the gross adjustments is exactly what's happening. No small adjustment seems to make any changes.
As everybody has said, I will try and lower RF signal till I see noise and play around till I see something happening . I wonder if I used the level input of my distortion meter and watched the analog gauge if that would show something? Or should I just stick with the scope?

 

[rcs16]

I use a analog AC voltmeter contained in the THD analyzer

 

[kenwoodm2a]

I use a analog AC voltmeter contained in the THD analyzer

That's what I meant. I have an analog ac voltmeter in my Amber 3501 distortion analyzer . So I could use that as well as my scope?

 

[rcs16]

Yes, I use my Amber 3501 too for this setup. I do not even bother using a scope for this test.

 

[kenwoodm2a]

So I'm having a little difficulty with some of these alignments and need some help from you experts.

I followed the suggestions that you guys made about lowering the output of the generator for alignment # 5 and 6 to the point that I see noise on the scope but even with drastic changes to the coils, seen very little changes on the scope. I did notice some changes to the strength meter display however even though they were small, I did peak for maximum on the meter display so I guess that's the best that can be done with that.

One of the problems I'm still trying to make sure that I'm getting right is the generator output settings.

Alignment # 7, 8, and 9 call for very low output of the generator.

# 7 calls for 2 - 3 dbu, # 8 calls for 12 dBu and # 9 calls for 43 dBu.

My generator outputs in dBu EMF so I have been using the following converter.....
https://www.eeweb.com/tools/rf-unit-converter

Attached are some pics of how I have my generator connected to my tuner. As you can see, I gutted and modified the 300 ohm to 75 ohm adaptor which is connected to a resistive 50 ohm to 75 ohm matching pad that is connected to the 50 ohm output of my generator using a 50 ohm BNC cable. I then need to adjust the generator output voltage to 1.55 times due to the losses in the resistive pad which I constructed from this site....... http://ham-radio.com/k6sti/match.htm

So for example, alignment # 9 calls for 43 dBu (Ant Input). According to the converter tool, 43 dBu equals 141 uV. If I multiply the 141 x 1.55= 218.55 uV.
Now if I place that 218.55uV into the uV box in the converter, the dBuV has now changed to 46.8 and the dBu EMF box is now showing 52.8. So the 52.8 dBu EMF is what I'm setting my generator for.

Same thing applies to alignment # 7 and # 8..... I use the same procedure for calculating the output of my generator for all settings ....... but yet # 7 and # 8 don't seem to have enough output to get any results.

Checking the IFT as in procedure # 7 made absolutely no changes to the scope display when adjusting the coils. I even tried using the level input of my distortion meter with no change so now I'm getting frustrated with the possibility that I'm doing something wrong.

Can anybody tell me if I'm doing this right? I need to know if I'm doing something wrong using the above online converter for these alignments cause if I don't have the correct Ant Input, then I can't accurately adjust # 8 for the stereo light and # 9 for the signal meter display.

I did manage to figure out # 10 and most of the other settings after but I do have another question.
Using # 10 as an example, it ask for an input setting of 10Hz 100-150kHz dev.
I don't believe that I can set my FM generator for a frequency other then the internal 1 kHz or 400 H signal which means that I need to feed an external 10 Hz signal into it which I did from another generator. My FM generator modulation can only be set from 0 to 100 dev so I'm not sure how I'm suppose to get 100-150 kHz dev. Am I missing something??

Any help would be greatly appreciated!

 

[rcs16]

rest there procedure for now, try my tests
do not use the scope. measure the quieting sensitivity, that is an un-modulated carrier, muting off on the tuner, rf off, use your AC voltmeter, no filters, to monitor the noise on either L or R o/p, it jumps around like it should but you can average it out, increase rf level to get your -3dB, and so on quieting curve to the noise floor of the tuner. you can measure this quieting sensitivity at low mid and high band. post them. compare to what they say it should be in the specs.

 

[kenwoodm2a]

rest there procedure for now, try my tests
do not use the scope. measure the quieting sensitivity, that is an un-modulated carrier, muting off on the tuner, rf off, use your AC voltmeter, no filters, to monitor the noise on either L or R o/p, it jumps around like it should but you can average it out, increase rf level to get your -3dB, and so on quieting curve to the noise floor of the tuner. you can measure this quieting sensitivity at low mid and high band. post them. compare to what they say it should be in the specs.

To which numbered procedure on the alignment sheet are you making reference too?

 

[rcs16]

it is not part of the alignment procedure, it is a test I asked you to perform and post the results.