You should be connecting your signal generator to pin 8 of the 12SA7, through a .1 MFD cap. Going through pin 4 of the 12SK7 is a useless step, unless the IF transformers are badly out of tune (going through pin 4 of the 12SK7 skips the 1st IF transformer and feeds into the 2nd IF transformer only). Be sure that your signal generator wire is shielded. If not, the signal will radiate everywhere, and it'll be difficult to tell if the IF transformers are peaking or not.
If you are doing everything as you should and the radio still won't peak with your generator, check to see if it is receiving stations well. The 66X1 has fixed mica capacitors in the base of each IF transformer. If they go bad, the IF transformers will not peak. If the radio performs well, try to peak the IF transformers using a weak station. If you can peak them and all stations line up, then the radio is likely working as it should. If not, it may be necessary to drill out the old capacitors and install new ones across the IF transformer leads under the chassis. New capacitors should range from about 80 to 200 pF.
The 66X1 is a fine performer. I have one, and I like it. The dial is also nice to look at once you get the pilot lamps centered on the glass.
T.
:
:You should be connecting your signal generator to pin 8 of the 12SA7, through a .1 MFD cap. Going through pin 4 of the 12SK7 is a useless step, unless the IF transformers are badly out of tune (going through pin 4 of the 12SK7 skips the 1st IF transformer and feeds into the 2nd IF transformer only). Be sure that your signal generator wire is shielded. If not, the signal will radiate everywhere, and it'll be difficult to tell if the IF transformers are peaking or not.
:
:If you are doing everything as you should and the radio still won't peak with your generator, check to see if it is receiving stations well. The 66X1 has fixed mica capacitors in the base of each IF transformer. If they go bad, the IF transformers will not peak. If the radio performs well, try to peak the IF transformers using a weak station. If you can peak them and all stations line up, then the radio is likely working as it should. If not, it may be necessary to drill out the old capacitors and install new ones across the IF transformer leads under the chassis. New capacitors should range from about 80 to 200 pF.
:
:The 66X1 is a fine performer. I have one, and I like it. The dial is also nice to look at once you get the pilot lamps centered on the glass.
:
:T.
Thanks for the help, I will give it a try. The radio is picking up stations ok, but not strong. I am wondering about those caps. I love the look of this radio and would really like to get it working strong. One more question the band selector has three positions and it seems like two of the are broadcast band, but the furthest counter clockwise quiets down the background noise. Would you mind helping me understand this? Thanks.
T.
:
:T.
Thanks, that helps.
:
:You should be connecting your signal generator to pin 8 of the 12SA7, through a .1 MFD cap. Going through pin 4 of the 12SK7 is a useless step, unless the IF transformers are badly out of tune (going through pin 4 of the 12SK7 skips the 1st IF transformer and feeds into the 2nd IF transformer only). Be sure that your signal generator wire is shielded. If not, the signal will radiate everywhere, and it'll be difficult to tell if the IF transformers are peaking or not.
:
:If you are doing everything as you should and the radio still won't peak with your generator, check to see if it is receiving stations well. The 66X1 has fixed mica capacitors in the base of each IF transformer. If they go bad, the IF transformers will not peak. If the radio performs well, try to peak the IF transformers using a weak station. If you can peak them and all stations line up, then the radio is likely working as it should. If not, it may be necessary to drill out the old capacitors and install new ones across the IF transformer leads under the chassis. New capacitors should range from about 80 to 200 pF.
:
:The 66X1 is a fine performer. I have one, and I like it. The dial is also nice to look at once you get the pilot lamps centered on the glass.
:
:T.
I turned down the output on the signal generator and injected the signal on pin 8 of the 12sa7 and was able to peak both IF transformers. I noticed the second IF was unscrewed quite a bit so I decided to go ahead and inject the signal on pin 4 of the 12sk7 and see if I could adjust just the second IF and could not. No matter which way I turned the screw it made no difference. Does this mean it has a bad cap? Thanks, Ron
I just had an RCA that I was trying to align and drove me crazy until I tightened down all the adjustment screws and realigned it. Someone had backed them out quite a bit and I believe I was peaking them to an 'image' of the 455.
::First, be sure to turn down your signal generator's output control as low as possible so that you can barely hear the tone in the speaker. Turn the radio all the way up. If you are injecting too strong of a signal, you will activate the radio's AVC circuit, which will make volume changes difficult to detect.
::
::You should be connecting your signal generator to pin 8 of the 12SA7, through a .1 MFD cap. Going through pin 4 of the 12SK7 is a useless step, unless the IF transformers are badly out of tune (going through pin 4 of the 12SK7 skips the 1st IF transformer and feeds into the 2nd IF transformer only). Be sure that your signal generator wire is shielded. If not, the signal will radiate everywhere, and it'll be difficult to tell if the IF transformers are peaking or not.
::
::If you are doing everything as you should and the radio still won't peak with your generator, check to see if it is receiving stations well. The 66X1 has fixed mica capacitors in the base of each IF transformer. If they go bad, the IF transformers will not peak. If the radio performs well, try to peak the IF transformers using a weak station. If you can peak them and all stations line up, then the radio is likely working as it should. If not, it may be necessary to drill out the old capacitors and install new ones across the IF transformer leads under the chassis. New capacitors should range from about 80 to 200 pF.
::
::The 66X1 is a fine performer. I have one, and I like it. The dial is also nice to look at once you get the pilot lamps centered on the glass.
::
::T.
:
:I turned down the output on the signal generator and injected the signal on pin 8 of the 12sa7 and was able to peak both IF transformers. I noticed the second IF was unscrewed quite a bit so I decided to go ahead and inject the signal on pin 4 of the 12sk7 and see if I could adjust just the second IF and could not. No matter which way I turned the screw it made no difference. Does this mean it has a bad cap? Thanks, Ron
Ron, your radio may have some bad capacitors in the 2nd IF transformer. However, once you peak the 1st IF transformer, again turn down the output of your signal generator. As you make adjustments and get a louder signal, always turn down your signal generator. If your generator was really quiet to begin with and got louder once you adjusted the IF transformers, the AVC circuit might be activated by the stronger signal, which would make further peaking of the transformers rather difficult. Each time the signal gets louder, turn down your generator. Keep repeating this until you cannot get any improvement.
T.
:Ron's radio is slug tuned, so he cannot tighten down the cap screws. The capacitors in his IF transformers are fixed values.
:
:Ron, your radio may have some bad capacitors in the 2nd IF transformer. However, once you peak the 1st IF transformer, again turn down the output of your signal generator. As you make adjustments and get a louder signal, always turn down your signal generator. If your generator was really quiet to begin with and got louder once you adjusted the IF transformers, the AVC circuit might be activated by the stronger signal, which would make further peaking of the transformers rather difficult. Each time the signal gets louder, turn down your generator. Keep repeating this until you cannot get any improvement.
:
:T.
:
::Ron's radio is slug tuned, so he cannot tighten down the cap screws. The capacitors in his IF transformers are fixed values.
::
::Ron, your radio may have some bad capacitors in the 2nd IF transformer. However, once you peak the 1st IF transformer, again turn down the output of your signal generator. As you make adjustments and get a louder signal, always turn down your signal generator. If your generator was really quiet to begin with and got louder once you adjusted the IF transformers, the AVC circuit might be activated by the stronger signal, which would make further peaking of the transformers rather difficult. Each time the signal gets louder, turn down your generator. Keep repeating this until you cannot get any improvement.
::
::T.
::
:::Ron's radio is slug tuned, so he cannot tighten down the cap screws. The capacitors in his IF transformers are fixed values.
:::
:::Ron, your radio may have some bad capacitors in the 2nd IF transformer. However, once you peak the 1st IF transformer, again turn down the output of your signal generator. As you make adjustments and get a louder signal, always turn down your signal generator. If your generator was really quiet to begin with and got louder once you adjusted the IF transformers, the AVC circuit might be activated by the stronger signal, which would make further peaking of the transformers rather difficult. Each time the signal gets louder, turn down your generator. Keep repeating this until you cannot get any improvement.
:::
:::T.
I did as you said and kept turning down the signal and even hooked up my digial meter across the speaker and peaked the first IF and the second. The radio seems to be picking up ok, but nothing on the short wave, admittedly I did not hook up an antenna, but I thought I might recieve a faint signal. That is why I went back to injecting the signal into the second IF to see if I could peak it and I could not. No matter how much I turned it never changed. I am baffled why I could peak both tranformers when I injected it into the first IF, but when I inject it into the second - nothing. I am not sure I am making sense. Mostly I am just trying to learn this whole alignment procedure, I am thinking of it as my next stage in reparing radios. Thanks for all of your help.
:::
::::Ron's radio is slug tuned, so he cannot tighten down the cap screws. The capacitors in his IF transformers are fixed values.
::::
::::Ron, your radio may have some bad capacitors in the 2nd IF transformer. However, once you peak the 1st IF transformer, again turn down the output of your signal generator. As you make adjustments and get a louder signal, always turn down your signal generator. If your generator was really quiet to begin with and got louder once you adjusted the IF transformers, the AVC circuit might be activated by the stronger signal, which would make further peaking of the transformers rather difficult. Each time the signal gets louder, turn down your generator. Keep repeating this until you cannot get any improvement.
::::
::::T.
:
:I did as you said and kept turning down the signal and even hooked up my digial meter across the speaker and peaked the first IF and the second. The radio seems to be picking up ok, but nothing on the short wave, admittedly I did not hook up an antenna, but I thought I might recieve a faint signal. That is why I went back to injecting the signal into the second IF to see if I could peak it and I could not. No matter how much I turned it never changed. I am baffled why I could peak both tranformers when I injected it into the first IF, but when I inject it into the second - nothing. I am not sure I am making sense. Mostly I am just trying to learn this whole alignment procedure, I am thinking of it as my next stage in reparing radios. Thanks for all of your help.
One More question, there are lugs under the chasis and on top, do you peak both of them?
Tony, with slug tuned IF transformers it isn't quite as easy as tightening trimmer capacitors down. Center of travel is where the slugs create maximum inductance. Up or down from there creates minimum inductance. If you have the can removed from the IF transformer in question, you can eyeball where the slug is, and start it at a point where it's completely inside of the coil it adjusts. However, if you don't remove the can, you can't really tell where the coils are, so you won't know where to put the slugs as a starting point. Of course you could always turn them completely out and start from there.
With the bottom slug all the way up and the top slug all the way down so that the two meet, greater coupling and bandwidth occurs, which isn't usually desirable. Normally you want the bandwidth to be more narrow, so it is best to always adjust the lower slug from the center of its travel downward, and the upper slug from the center of its travel upward. That will give you a better peak. .....Or start with the bottom slug all the way down and the top slug all the way up, and go down from there, though you'll be starting at higher frequencies (lower inductance) and will be working towards lower frequencies, so there is more of a chance that you could align to a harmonic. If in doubt, go for the loudest point of resonance. If your signal generator is accurate, the correct resonance point will be the loudest one. I don't usually run into trouble with harmonics at IF frequencies, though I guess you could.
With any trimming device, be it capacitive or inductive, you don't know how well matched the device is with whatever it is supposed to resonate with (capacitor trimmer with a coil, and inductive trimmer (coil) with a fixed capacitor), so proper resonance could happen anywhere in the mechanical travel of the trimming device. For screw type capacitive trimmers resonance is usually found at some point just a bit up from tight down, though not always. There are some radios in which the trimmers are opened up quite a bit before resonance is found.
T.
Sir Ron........
I caught your final query about the "lug(s) " on the bottom of the set and thought possibly that you had only covered two slugs out of 4 in your adjustments. Also, with the tuning response effect probably masked by too strong of a signal from your signal generator, and a swamping of the unit with the IF signal. Thus, the need of setting the generators attenuator for less signal OR a possible distancing of the unit from the receiver if it is still too strong.
Sooooo...what I have done is finished my posting that was disrupted earlier, and posted it separately as a new byline.
I do see that Sir Thomas...the Big Bad Pirate.... has come back in the interim and coincidentally happened to have touched upon a few common points.
Additionally, you mention the use of digital metering, which is fine for reading out 5.467 volts AC or DC but could certainly be bested by the use of analog metering when doing alignment metering. It is so nice to see a meters pointer responding ever so exactly to a changing signal as compared to a digital units refresh sampling bobblings, that mask finite transitions. Even my combo Flukes with the "analog" hash marks doesn’t do it, because the marked step increments are spaced so far apart .
If one uses an analog meter *** connected to the AVC bus for the final tweaking of an alignment , you can then monitor for a max negative voltage peaking and cumulatively peak the system so that even a 1/32--1/64 th of a TURN of a single slug can make a difference in the overall tuning of a system. Then you will be getting a finite, empirical figure that you can see, and not merely be relying upon an aural response of your hearing when using a tone modulated signal.
***[ Specifically, a VTVM, TVM, or FET VM, so that the input impedance of that metering will not be loading down that AVC buss and pulling it down in its overall – DC level ]
Refer to ye olden HOT link:
http://www.nostalgiaair.org/Forums/messages/272/M0060272.htm
73's de Edd
