Hi,
I have a Sansui TU-717. This tuner is functional, but I have perceptible distortion on all FM stations. According to the signal meter the strength is not the problem. I always get above 4/5, and more often it looks like 4.9/5. The only other unusual this is that the station are ot on the spot, i.e. I get 95.1FM at 94.9. I don't care about this small deviation, what I care more is about the distortion.
The distortion is not extreme, my girlfriend cannot get what I am talking about, but an audiophile friend picked it up right away.
Everything else is perfect, i.e. stereo light, tunning meter, etc.
I would like to get rid of the distortion, but I don't know where to start. I know we can upgrade those tuner, but my main objective here is to get rid of the distortion.
If you can help me identify the cause or better find a solution I would be please.
I have a Sansui TU-717. This tuner is functional, but I have perceptible distortion on all FM stations. According to the signal meter the strength is not the problem. I always get above 4/5, and more often it looks like 4.9/5. The only other unusual this is that the station are ot on the spot, i.e. I get 95.1FM at 94.9. I don't care about this small deviation, what I care more is about the distortion.
The distortion is not extreme, my girlfriend cannot get what I am talking about, but an audiophile friend picked it up right away.
Everything else is perfect, i.e. stereo light, tunning meter, etc.
I would like to get rid of the distortion, but I don't know where to start. I know we can upgrade those tuner, but my main objective here is to get rid of the distortion.
If you can help me identify the cause or better find a solution I would be please.
Hi
I just got done tweaking TU-717. Its quite astonishing after $20 filter mods and alignment:
WIDE
Mono .015% both channels
L+R .016/.022
L-R .083
SEP 58dB
NARROW
Mono .123% both channels
L+R .129%
L-R .104%
SEP. 28dB (with a dual separation pot relay it would be 50db)
@91.1Mhz,72dbf, 75khz deviation, 1.023khz mod, 9% pilot, no SCA, no RDS
So your tuner is capable of much better performance. The audio circuits have a lot of coupling caps to replace for best bass. You would be hard pressed to better it for the money. A Tu-517 is very slightly better at rejecting MPX noise on weak stations.
If you have any q's feel free to contact me
John
I just got done tweaking TU-717. Its quite astonishing after $20 filter mods and alignment:
WIDE
Mono .015% both channels
L+R .016/.022
L-R .083
SEP 58dB
NARROW
Mono .123% both channels
L+R .129%
L-R .104%
SEP. 28dB (with a dual separation pot relay it would be 50db)
@91.1Mhz,72dbf, 75khz deviation, 1.023khz mod, 9% pilot, no SCA, no RDS
So your tuner is capable of much better performance. The audio circuits have a lot of coupling caps to replace for best bass. You would be hard pressed to better it for the money. A Tu-517 is very slightly better at rejecting MPX noise on weak stations.
If you have any q's feel free to contact me
John
First some q's to help narrow down the problem
1)Can you describe in detail what the distortion sounds like?
2)Have you tried a different tuner to see if this distortion is still present?
3)Are you certain that your antenna is getting a good signal, not just a strong signal but one free of multipath?
4)Does the distortion change with antenna orientation or with a different station?
5)Are you using a directional outdoor antenna?
6)What is the distance to your station?
Increased distortion (THD) in FM tuners is caused by the drift and aging of critical circuits such as the ceramic filters and detector coils. This is more pronounced in vintage tuners suchas the TU-717.
On the Sansui I worked on the caps did not influence THD at all. The owner did not see the need to upgrade the caps as the midrange sound was so exceptional even with the old caps!
To my ears the tuner lacked low end that could be upgraded with bigger coupling caps. I have a more extensive list of cap modds than Jim but its muy $$$. Also there's stuff you can do to flatten the high freq. response and power supply upgrades but those are advanced mods.
There are no exact substitutes for Black Gates IMHO but you can use the richer sounding Elna Silmics or Cerafines in contrast to the thin sounding Nichicon Muse. Sanyo Oscons can sound good in some cases also.
Bigger caps = lower frequency response but do not cheat by using lower than 25V caps 50V is best. On the higher end tuners Sansui used a composite cap made from two back to back polar caps bypassed with a poly to good effect.
Electrolytic caps lifetime is typically 15 years under good conditions BUT they can last longer if they where high quality components to begin with. High temperatures degrade the caps much faster than that. Also if the unit was left unpowered for many years these caps will lose their polarization and will "leak' upon first power up. Old bad caps will sound fuzzy and ill-defined in the bass. When I get an old tuner I usually let it run-in for a few days before aligning it.
First I cleaned the frontend contacts with a pinpoint application of Deoxit.( See Audiokarma "how to clean an analog tuner " sticky).
I changed the wide and narrow ceramic filters with carefully matched ones from Bill Ammons (see FMtuners matched filter page).
The narrow filters came with an amplified filter board to compensate for the filter loss. I exchanged the ceramic caps in the detector circuit for polystyrene ones.
Then I re-aligned the detector coils and IF group delay equalizer for lowest distortion and reset the separation pot for best separation.
Unfortunately to do this crucial step you need some rather specialized test equipment like a FM stereo signal generator in good calibration. You will not get proper results just by swapping in filters and caps. So as Salas said you need to find a GOOD tuner tech WILLING to do this.I don't know any tuner techs in Montreal, but Mike Williams or I could easily tune-up a 717 as long as you can ship it to the 'states
John
1)Can you describe in detail what the distortion sounds like?
2)Have you tried a different tuner to see if this distortion is still present?
3)Are you certain that your antenna is getting a good signal, not just a strong signal but one free of multipath?
4)Does the distortion change with antenna orientation or with a different station?
5)Are you using a directional outdoor antenna?
6)What is the distance to your station?
Increased distortion (THD) in FM tuners is caused by the drift and aging of critical circuits such as the ceramic filters and detector coils. This is more pronounced in vintage tuners suchas the TU-717.
On the Sansui I worked on the caps did not influence THD at all. The owner did not see the need to upgrade the caps as the midrange sound was so exceptional even with the old caps!
To my ears the tuner lacked low end that could be upgraded with bigger coupling caps. I have a more extensive list of cap modds than Jim but its muy $$$. Also there's stuff you can do to flatten the high freq. response and power supply upgrades but those are advanced mods.
There are no exact substitutes for Black Gates IMHO but you can use the richer sounding Elna Silmics or Cerafines in contrast to the thin sounding Nichicon Muse. Sanyo Oscons can sound good in some cases also.
Bigger caps = lower frequency response but do not cheat by using lower than 25V caps 50V is best. On the higher end tuners Sansui used a composite cap made from two back to back polar caps bypassed with a poly to good effect.
Electrolytic caps lifetime is typically 15 years under good conditions BUT they can last longer if they where high quality components to begin with. High temperatures degrade the caps much faster than that. Also if the unit was left unpowered for many years these caps will lose their polarization and will "leak' upon first power up. Old bad caps will sound fuzzy and ill-defined in the bass. When I get an old tuner I usually let it run-in for a few days before aligning it.
First I cleaned the frontend contacts with a pinpoint application of Deoxit.( See Audiokarma "how to clean an analog tuner " sticky).
I changed the wide and narrow ceramic filters with carefully matched ones from Bill Ammons (see FMtuners matched filter page).
The narrow filters came with an amplified filter board to compensate for the filter loss. I exchanged the ceramic caps in the detector circuit for polystyrene ones.
Then I re-aligned the detector coils and IF group delay equalizer for lowest distortion and reset the separation pot for best separation.
Unfortunately to do this crucial step you need some rather specialized test equipment like a FM stereo signal generator in good calibration. You will not get proper results just by swapping in filters and caps. So as Salas said you need to find a GOOD tuner tech WILLING to do this.I don't know any tuner techs in Montreal, but Mike Williams or I could easily tune-up a 717 as long as you can ship it to the 'states
John
Hi Salas,
Thank you for the plug. You're very kind.
Hi spacemen12,
I often find the demodulator (quadrature coil or discriminator coil) is out of alignment. That will greatly affect the distortion. Sometimes coupling caps can age, but this would more likely create a different type of distortion rather than just bass loss. The power supply should also be checked out at this age.
The other dreaded fault is someone who gets in there and just starts adjusting things. That can create lengthly repairs, so can component replacement by people who don't solder well.
I do audio service, including complete tuner alignments. My equipment is pretty much all Hewlett Packard, with one Radiometer Copenhagen stereo generator thrown in for good measure.
Now, if you are not in a rush I might be able to help you. Right now I'm pretty busy with work. Just use the button below to send me a message.
-Chris
Thank you for the plug. You're very kind.
Hi spacemen12,
I often find the demodulator (quadrature coil or discriminator coil) is out of alignment. That will greatly affect the distortion. Sometimes coupling caps can age, but this would more likely create a different type of distortion rather than just bass loss. The power supply should also be checked out at this age.
The other dreaded fault is someone who gets in there and just starts adjusting things. That can create lengthly repairs, so can component replacement by people who don't solder well.
I do audio service, including complete tuner alignments. My equipment is pretty much all Hewlett Packard, with one Radiometer Copenhagen stereo generator thrown in for good measure.
Now, if you are not in a rush I might be able to help you. Right now I'm pretty busy with work. Just use the button below to send me a message.
-Chris
Hi spacemen12,
-Chris
Ceramic filters do not often drift that far. The initial center frequencies are not very tight either. Worrying about this is more of an improvement and you may not notice it.
Still sounds like your FM detector.
That happens when the signal bounces off a building or some other surface. The direct signal arrives, but the reflected signal arrives a touch later and interacts with your direct signal. Since they are on the same frequency, the interaction passes through. The only way to "fix" a multipath situation would be to use a directional antenna aimed to reduce the strength of the reflected signal. This will probably not be the direction that gives you the strongest desired signal.
-Chris
Have you tried to switch to Mono? Is than distortion lower than in stereo mode?
You can match to the right frequency of the broadcasting station with trim. potentiometers on the PCB inside, but that is work for the technician.
Also try to connect just piece of wire about 70 cm long ( to the hot point of the coaxial Ant. connector) , perhaps your signal is coming too strong!!! and see if that makes any difference in distortion.
You can match to the right frequency of the broadcasting station with trim. potentiometers on the PCB inside, but that is work for the technician.
Also try to connect just piece of wire about 70 cm long ( to the hot point of the coaxial Ant. connector) , perhaps your signal is coming too strong!!! and see if that makes any difference in distortion.
Hi spacemen12,
Honestly, if you aren't suffering from multi-path, and you aren't as this is across the band, the problem is occurring before your MPX stage. That would be the detector stage, and the adjustments there do require signal generators and instruments.
This problem seems to be becoming more common as time goes by. What I can tell you is that you are by no means alone with this problem. Yours might just be a little worse.
It is possible that there has been a component failure, but that also requires that a good technician looks at it. Too many pot twisters out there these days.
-Chris
All I can really say is that ....
Honestly, if you aren't suffering from multi-path, and you aren't as this is across the band, the problem is occurring before your MPX stage. That would be the detector stage, and the adjustments there do require signal generators and instruments.
This problem seems to be becoming more common as time goes by. What I can tell you is that you are by no means alone with this problem. Yours might just be a little worse.
It is possible that there has been a component failure, but that also requires that a good technician looks at it. Too many pot twisters out there these days.
-Chris
Hi spacemen,
There is a simple voltage test point that you can check to see how far your detector is off center.
If you look inside your 717 you will see a rectangular steel box enclosing the detector circuit. (close to the power trans.)
There are three holes on the one side, the larger hole has a test point located at the center. Measure the voltage referenced to ground ie the chassis. Do this while center tuned to a strong station.
This voltage should be 0mv at the exact center of the tuned station. If it is not and the tuning indicator shows an offset to either side the the tuner needs an alignment to get the indicator to match with lowest distortion
BTW the filters are a considerable improvement as the distortion went from .1% with old 280s in wide to .016 with the new matched ones. Narrow is now close to the old wide mode.
This is because the 717 has a special group delay eq circuit which cancels out the distortion generating group delay of ceramic filters. As there is only one adjustment, matched filters are much better since they "delay" the same amount at the same frequency, enabling the the GD Eq to cancel almost all to the distortion. Also sensitivity/selectivity is enhanced as the filters are all centered perfectly, something you will not find in a production tuner, as anatech says.
So for a meager $20 + the cost of an alignment you get a tuner that is considered a "giant killer"
I'll leave the "you may not notice" judgement to ear of the beholder
There is a simple voltage test point that you can check to see how far your detector is off center.
If you look inside your 717 you will see a rectangular steel box enclosing the detector circuit. (close to the power trans.)
There are three holes on the one side, the larger hole has a test point located at the center. Measure the voltage referenced to ground ie the chassis. Do this while center tuned to a strong station.
This voltage should be 0mv at the exact center of the tuned station. If it is not and the tuning indicator shows an offset to either side the the tuner needs an alignment to get the indicator to match with lowest distortion
BTW the filters are a considerable improvement as the distortion went from .1% with old 280s in wide to .016 with the new matched ones. Narrow is now close to the old wide mode.
This is because the 717 has a special group delay eq circuit which cancels out the distortion generating group delay of ceramic filters. As there is only one adjustment, matched filters are much better since they "delay" the same amount at the same frequency, enabling the the GD Eq to cancel almost all to the distortion. Also sensitivity/selectivity is enhanced as the filters are all centered perfectly, something you will not find in a production tuner, as anatech says.
So for a meager $20 + the cost of an alignment you get a tuner that is considered a "giant killer"
I'll leave the "you may not notice" judgement to ear of the beholder
Hi robjak,
The alternative method which always works perfectly is to inject your own 10.7 MHz signal into the IF strip. You get a better alignment that way. Of course, this means that you need test equipment.
After this is done, you can then align the detector for distortion using the same test signal injection point and actually get it bang on. After that, you can properly align the IF transformer in the front end properly.
Hey, if you can do this job properly for $20, have at 'er. It takes longer to get the tuner ready for alignment than that. Not unless you are suggesting that you just pop the lid and select a station, then twist the control. BTW, there is also normally and adjustment for tuning voltage span, and that does affect the sensitivity.
Sounds like an honest hour of time to me.
-Chris
Yes, that is correct. Most manuals will instruct you to tune to a place where there are no transmissions, but I find that there is enough skip and interference that this is not possible these days.
The alternative method which always works perfectly is to inject your own 10.7 MHz signal into the IF strip. You get a better alignment that way. Of course, this means that you need test equipment.
After this is done, you can then align the detector for distortion using the same test signal injection point and actually get it bang on. After that, you can properly align the IF transformer in the front end properly.
Hey, if you can do this job properly for $20, have at 'er. It takes longer to get the tuner ready for alignment than that. Not unless you are suggesting that you just pop the lid and select a station, then twist the control. BTW, there is also normally and adjustment for tuning voltage span, and that does affect the sensitivity.
Sounds like an honest hour of time to me.
-Chris
Hi anatech,
This is exactly how I align the IF and detector stage in an analog tuner. Then I go back to the front end and align the mixer output transformer for lowest distortion/max sensitivity in stereo. Sometimes its a tradeoff.
Yes the varactor tuning voltage range is the first thing you set on a PLL synthesized "digital". On an analog you check dial alignment and make it line-up with the stations.
Then you can "peak" the gangs using an iterative method with hi/low freq. Some feel this may not be optimal though and prefer a swept alignment
Swept Front-End Alignment
Most of the time the service manual procedures are wrong, outdated, or incomplete as is the case with the TU-717. Just another reason to have an experienced tech work on your tuner. There are quite a few tricks (and pitfalls) you learn only by working on a lot of different tuners.
For example you have to be very careful with the frontend inductor slugs in the 717. Mine were partially cracked from a previous "tech" and had siezed up not allowing me to align the tuner. Had to pull some slugs out of a scrap unit to get it going again
Note that I said "+ the cost of an alignment".
The filters/amp board cost an extra $20 for just for the parts. I throw in the labor to install them as part of the alignment labor cost. If you are going to take the time to do it right you should get paid for it!
My point was that if you're gonna have the unit aligned might as well get the filters put in as they are not a $12/pc Black Gate. They really help the tuner pick out the stations better, which is the primary function of a tuner.
This is exactly how I align the IF and detector stage in an analog tuner. Then I go back to the front end and align the mixer output transformer for lowest distortion/max sensitivity in stereo. Sometimes its a tradeoff.
Yes the varactor tuning voltage range is the first thing you set on a PLL synthesized "digital". On an analog you check dial alignment and make it line-up with the stations.
Then you can "peak" the gangs using an iterative method with hi/low freq. Some feel this may not be optimal though and prefer a swept alignment
Swept Front-End Alignment
Most of the time the service manual procedures are wrong, outdated, or incomplete as is the case with the TU-717. Just another reason to have an experienced tech work on your tuner. There are quite a few tricks (and pitfalls) you learn only by working on a lot of different tuners.
For example you have to be very careful with the frontend inductor slugs in the 717. Mine were partially cracked from a previous "tech" and had siezed up not allowing me to align the tuner. Had to pull some slugs out of a scrap unit to get it going again
Note that I said "+ the cost of an alignment".
The filters/amp board cost an extra $20 for just for the parts. I throw in the labor to install them as part of the alignment labor cost. If you are going to take the time to do it right you should get paid for it!
My point was that if you're gonna have the unit aligned might as well get the filters put in as they are not a $12/pc Black Gate. They really help the tuner pick out the stations better, which is the primary function of a tuner.
Hi robjak,
Well, we seem to be talking the same language. Sorry for the misunderstanding. It's nifty that the alignment procedure I posted was one I came up with on my own after years of frustrating outcomes by following the service manual. What's cool is that it matches what you are doing as well. Mind you, on some products, the procedure in the manual is the one that works. Revox tuners are a good example of that.
Tell me, I assume that you sweep the ceramic resonators to grade them, what test circuit do you use for this? Also, what do you do with the off center resonators? You can't really set up for a non-standard IF frequency or you will have tracking problems.
-Chris
Well, we seem to be talking the same language. Sorry for the misunderstanding. It's nifty that the alignment procedure I posted was one I came up with on my own after years of frustrating outcomes by following the service manual. What's cool is that it matches what you are doing as well. Mind you, on some products, the procedure in the manual is the one that works. Revox tuners are a good example of that.
Tell me, I assume that you sweep the ceramic resonators to grade them, what test circuit do you use for this? Also, what do you do with the off center resonators? You can't really set up for a non-standard IF frequency or you will have tracking problems.
-Chris
Hi spacemen12,
The better, more experienced techs can get by with less equipment, so they may say something like "I don't need all that stuff". But they do if they want to do a really good job.
This is another one of those jobs that you really shouldn't start out on. So my advice is to let an experienced technician do the job. That means an experienced audio only technician.
-Chris
Soft tuning wands and experience.
You will also need a good distortion analyzer and possibly adapters from 50R lines to 75R lines. Then you need to have the "feel" so you don't damage any cores you may come across. I would say that a spectrum analyzer would be invaluable.
The better, more experienced techs can get by with less equipment, so they may say something like "I don't need all that stuff". But they do if they want to do a really good job.
This is another one of those jobs that you really shouldn't start out on. So my advice is to let an experienced technician do the job. That means an experienced audio only technician.
-Chris
Hi anatech & spacemen12
I sourced the filters and IF Filter Adder Board from Bill Ammons specifically for the TU-717.
In order to do this myself I would have to purchase min qty lots of 500-1000 filters and hand-match them into bins.As Bill sells matched sets for only $2 a filter its a no-brainer. That is unless you LIKE sorting hundreds of filters
For offcenter filters, analog tuners don't seem to care much if the matched filters are +-30khz as long as the IF and detector adjustments have enough range, a given in production tuners
Digitals OTOH need 10.700Mhz unless modifcations to the PLL xtal osc are made
Accomodating Offcenter IF Filters
The exceptions are the CSL Yamahas which have a IF offset adjustment which allows a wide range of 10.7ish filters (matched set of course)
BTW Murata has ceased production of the low GDT filters needed for high quality tuners due to low demand. Get NOS while you still can.
What you need to properly align a TU-717 (What I use currently)
1) Low distortion (<=0.01% stereo@10.7Mhz and 88-108Mhz) FM stereo genset specifically designed for low distortion tuner alignment (Levear,Leader,Panasonic,Meguro,Kenwood,others..)
2) High quality externally powered USB/firewire 24/96k soundcard (maudio,etc)
3) >1Ghz Laptop running 16-24bit FFT analyzer software to quantify distortion and separation
4) A good DMM
5) Good shielded cabling/connectors to avoid interference, especially during sensitivity testing
6) Matching 50Ù to 75Ù
7) Tools
8) Service Manual and addendums
9) Caig deoxit needle applicator and MCL
10) Some spare frontend slugs in case yours crack(ed) If they don't turn with mild pressure then they WILL crack when forced
11) Alignment procedures that work
12) Time and patience to learn how to effectively use all of the above = experience
This is not to say that there are no shortcuts, but I try to get better than factory spec out of a tuner
Yeah I need an RF spectrum analyser with tracking gen. but its big $$$ even on the 'Bay.
I sourced the filters and IF Filter Adder Board from Bill Ammons specifically for the TU-717.
In order to do this myself I would have to purchase min qty lots of 500-1000 filters and hand-match them into bins.As Bill sells matched sets for only $2 a filter its a no-brainer. That is unless you LIKE sorting hundreds of filters
For offcenter filters, analog tuners don't seem to care much if the matched filters are +-30khz as long as the IF and detector adjustments have enough range, a given in production tuners
Digitals OTOH need 10.700Mhz unless modifcations to the PLL xtal osc are made
Accomodating Offcenter IF Filters
The exceptions are the CSL Yamahas which have a IF offset adjustment which allows a wide range of 10.7ish filters (matched set of course)
BTW Murata has ceased production of the low GDT filters needed for high quality tuners due to low demand. Get NOS while you still can.
What you need to properly align a TU-717 (What I use currently)
1) Low distortion (<=0.01% stereo@10.7Mhz and 88-108Mhz) FM stereo genset specifically designed for low distortion tuner alignment (Levear,Leader,Panasonic,Meguro,Kenwood,others..)
2) High quality externally powered USB/firewire 24/96k soundcard (maudio,etc)
3) >1Ghz Laptop running 16-24bit FFT analyzer software to quantify distortion and separation
4) A good DMM
5) Good shielded cabling/connectors to avoid interference, especially during sensitivity testing
6) Matching 50Ù to 75Ù
7) Tools
8) Service Manual and addendums
9) Caig deoxit needle applicator and MCL
10) Some spare frontend slugs in case yours crack(ed) If they don't turn with mild pressure then they WILL crack when forced
11) Alignment procedures that work
12) Time and patience to learn how to effectively use all of the above = experience
This is not to say that there are no shortcuts, but I try to get better than factory spec out of a tuner
Yeah I need an RF spectrum analyser with tracking gen. but its big $$$ even on the 'Bay.
Hi robjak,
I do have a bunch of filters also. I match them using a spectrum analyzer, but I often don't need to install a matched set. Most of the tuners I see are out of alignment, and some from different areas see to be wayyy out of alignment. Looks like the resident Mr Fix-it, can't.
I find that everyone so far is so happy with their aligned tuner that replacing the IF filters is not required. The performance always exceeds the listed spec. There are times I need to improve the audio path. I have even eliminated that "Pioneer sound" from their tuners. After this, they sound great, more open without that funny midrange thing going on. Of course, I can just leave it if the customer prefers.
I am using an HP 8656A, 8640B and a Radiometer SMG1 for a generator. I also have an HP 8901A and Boonton 82AD Modulation analyzer to confirm the generators are working properly. An HP 5335A with oven oscillator option confirms frequencies. I use an HP3585A Spectrum Analyzer to look at the IF response. I am looking for an RF model, sometime in the future I guess.
I noticed you are using an HP 3336B Signal Generator. This will couple to an HP 3586B Selective Voltmeter to give you a system that will sweep an IF strip easily. The 3336B will track the 3586B and you can connect a scope as well to give you a visual. One of those USB digital scopes would work very well for this as they don't need to refresh the screen quickly.
So, what method do you use to match your filters?
-Chris
Edit: $7.00 for a service bulletin is highway robbery! $11.95 for a PDF isn't cheap either. Do you get your manuals here and at these prices?
I do have a bunch of filters also. I match them using a spectrum analyzer, but I often don't need to install a matched set. Most of the tuners I see are out of alignment, and some from different areas see to be wayyy out of alignment. Looks like the resident Mr Fix-it, can't.
I find that everyone so far is so happy with their aligned tuner that replacing the IF filters is not required. The performance always exceeds the listed spec. There are times I need to improve the audio path. I have even eliminated that "Pioneer sound" from their tuners. After this, they sound great, more open without that funny midrange thing going on. Of course, I can just leave it if the customer prefers.
I am using an HP 8656A, 8640B and a Radiometer SMG1 for a generator. I also have an HP 8901A and Boonton 82AD Modulation analyzer to confirm the generators are working properly. An HP 5335A with oven oscillator option confirms frequencies. I use an HP3585A Spectrum Analyzer to look at the IF response. I am looking for an RF model, sometime in the future I guess.
I noticed you are using an HP 3336B Signal Generator. This will couple to an HP 3586B Selective Voltmeter to give you a system that will sweep an IF strip easily. The 3336B will track the 3586B and you can connect a scope as well to give you a visual. One of those USB digital scopes would work very well for this as they don't need to refresh the screen quickly.
So, what method do you use to match your filters?
-Chris
Edit: $7.00 for a service bulletin is highway robbery! $11.95 for a PDF isn't cheap either. Do you get your manuals here and at these prices?
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