This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
Thanks,
Dave
I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
Thanks,
Dave
:Hello All,
: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
:
:Thanks,
:
:Dave
:
:Hello Again All,
: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
:
:Thanks,
:
:Dave
::Hello All,
:: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
:: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
::
::Thanks,
::
::Dave
::
:
:
:
:
::Hello Again All,
:
:: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
::
::Thanks,
::
::Dave
:::Hello All,
::: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
::: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
:::
:::Thanks,
:::
:::Dave
:::
::
:
A couple of comments. First, unless there is a separate section on the tuning capacitor for each band, which would be unusual and require a REALLY long tuning cap, I'd discount that as part of the problem.
I'd suspect silver-mica disease in the trimmer cap for this band. Two simple tests might reveal this. A) the noise is gone when the volume is turned down, and 2)tapping it makes it better or worse. Remember these are not definitive tests, but might help narrow the problem.
Good luck,
Terry
Are you talking about the SW Padder, not attached to the tuning capacitor?
Thanks,
Dave
::Hi Dave, I had a very similar problem on a radio I found in a barn. It had been exposed to the elements for 15+ years. The shaft that the cap. plates were mounted on had some kind of semi conductive buildup on it shorting it to ground at some points thru the tuning range. Contact cleaner and compressed air eventually got it clean, and it now performs very well.
::
::
::
:::Hello Again All,
::
::: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
:::
:::Thanks,
:::
:::Dave
::::Hello All,
:::: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
:::: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
::::
::::Thanks,
::::
::::Dave
::::
:::
::
:
:Hi Dave-
:A couple of comments. First, unless there is a separate section on the tuning capacitor for each band, which would be unusual and require a REALLY long tuning cap, I'd discount that as part of the problem.
:I'd suspect silver-mica disease in the trimmer cap for this band. Two simple tests might reveal this. A) the noise is gone when the volume is turned down, and 2)tapping it makes it better or worse. Remember these are not definitive tests, but might help narrow the problem.
:Good luck,
:Terry
:
: Are you talking about the SW Padder, not attached to the tuning capacitor?
Yeah. This doesn't sound to me like a tuning cap problem, or it'd be on all the bands. I might be wrong about it being the trimmer, or padder, but I'll bet it's in the tuning circuit for just that band.
But I've been wrong before, in '98 I think, on a Thursday afternoon.
Ha ha
T.
:
:Thanks,
:
:Dave
:::Hi Dave, I had a very similar problem on a radio I found in a barn. It had been exposed to the elements for 15+ years. The shaft that the cap. plates were mounted on had some kind of semi conductive buildup on it shorting it to ground at some points thru the tuning range. Contact cleaner and compressed air eventually got it clean, and it now performs very well.
:::
:::
:::
::::Hello Again All,
:::
:::: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
::::
::::Thanks,
::::
::::Dave
:::::Hello All,
::::: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
::::: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
:::::
:::::Thanks,
:::::
:::::Dave
:::::
::::
:::
::
::Hi Dave-
::A couple of comments. First, unless there is a separate section on the tuning capacitor for each band, which would be unusual and require a REALLY long tuning cap, I'd discount that as part of the problem.
::I'd suspect silver-mica disease in the trimmer cap for this band. Two simple tests might reveal this. A) the noise is gone when the volume is turned down, and 2)tapping it makes it better or worse. Remember these are not definitive tests, but might help narrow the problem.
::Good luck,
::Terry
::
:
All that's left to replace would be a mica capacitor. The resistors are all fine. I replaced all the paper and electrolytic capacitors.
It did make some difference cleaning the trimmer capacitors. Trying to adjust the padder got me the shock, which reminded me to disconnect the other end of the capacitor on top of the chassis. So that was good too.
Thanks,
Dave
::Terry,
:: Are you talking about the SW Padder, not attached to the tuning capacitor?
:
:Yeah. This doesn't sound to me like a tuning cap problem, or it'd be on all the bands. I might be wrong about it being the trimmer, or padder, but I'll bet it's in the tuning circuit for just that band.
:
:But I've been wrong before, in '98 I think, on a Thursday afternoon.
:Ha ha
:T.
::
::Thanks,
::
::Dave
::::Hi Dave, I had a very similar problem on a radio I found in a barn. It had been exposed to the elements for 15+ years. The shaft that the cap. plates were mounted on had some kind of semi conductive buildup on it shorting it to ground at some points thru the tuning range. Contact cleaner and compressed air eventually got it clean, and it now performs very well.
::::
::::
::::
:::::Hello Again All,
::::
::::: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
:::::
:::::Thanks,
:::::
:::::Dave
::::::Hello All,
:::::: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
:::::: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
::::::
::::::Thanks,
::::::
::::::Dave
::::::
:::::
::::
:::
:::Hi Dave-
:::A couple of comments. First, unless there is a separate section on the tuning capacitor for each band, which would be unusual and require a REALLY long tuning cap, I'd discount that as part of the problem.
:::I'd suspect silver-mica disease in the trimmer cap for this band. Two simple tests might reveal this. A) the noise is gone when the volume is turned down, and 2)tapping it makes it better or worse. Remember these are not definitive tests, but might help narrow the problem.
:::Good luck,
:::Terry
:::
::
:
I sprayed the trimmers mounted on the tuning capacitor with De-Ox-Id. The trimmer on the center tuning capacitor really was really staticy while turning it clockwise and then counter clockwise and spraying it some more. Now I am receiving stations above 10 Mc, one is around 12 Mc that sounds like it's in Japanese. That went off, and I hear radio Havana Cuba near that station. I believe that you are correct. The padder is difficult to get to without a mild shock. I think I need to disconnect the other wires connected to one side of the old capacitor on top of the chassis. It must have been shorted because it's live. But it's a very tiny current. I'll keep cleaning the trimmer until the static is gone. I don't hear much getting towards 18. But I don't think there's much up there. The short wave I usually listen to seems to be operational again.
Thanks very much,
Dave
::Hi Dave, I had a very similar problem on a radio I found in a barn. It had been exposed to the elements for 15+ years. The shaft that the cap. plates were mounted on had some kind of semi conductive buildup on it shorting it to ground at some points thru the tuning range. Contact cleaner and compressed air eventually got it clean, and it now performs very well.
::
::
::
:::Hello Again All,
::
::: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
:::
:::Thanks,
:::
:::Dave
::::Hello All,
:::: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
:::: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
::::
::::Thanks,
::::
::::Dave
::::
:::
::
:
:Hi Dave-
:A couple of comments. First, unless there is a separate section on the tuning capacitor for each band, which would be unusual and require a REALLY long tuning cap, I'd discount that as part of the problem.
:I'd suspect silver-mica disease in the trimmer cap for this band. Two simple tests might reveal this. A) the noise is gone when the volume is turned down, and 2)tapping it makes it better or worse. Remember these are not definitive tests, but might help narrow the problem.
:Good luck,
:Terry
:
: I sprayed the trimmers mounted on the tuning capacitor with De-Ox-Id. The trimmer on the center tuning capacitor really was really staticy while turning it clockwise and then counter clockwise and spraying it some more. Now I am receiving stations above 10 Mc, one is around 12 Mc that sounds like it's in Japanese. That went off, and I hear radio Havana Cuba near that station. I believe that you are correct. The padder is difficult to get to without a mild shock. I think I need to disconnect the other wires connected to one side of the old capacitor on top of the chassis. It must have been shorted because it's live. But it's a very tiny current. I'll keep cleaning the trimmer until the static is gone. I don't hear much getting towards 18. But I don't think there's much up there. The short wave I usually listen to seems to be operational again.
:
:Thanks very much,
:
:Dave
Dave-
Check out this link.
http://www.radiomuseum.org/forum/if_transformer_repair.html
The two plates that are separated by a piece of mica can develop a coating of carbon across them. This would certainly account for voltage appearing across the cap. I successfully repaired two caps in a couple of IF transformers. I had to cut out the plates and replace them with 75 picofarad mica caps. The link does not necessarily apply to your problem, but should still give you some useful information. I think the results of your tests prove you've found the source of the problem. You might have to replace the cap. It'd be nice if you have an RF generator to reset the IF frequency.
Good luck-
Terry
:::Hi Dave, I had a very similar problem on a radio I found in a barn. It had been exposed to the elements for 15+ years. The shaft that the cap. plates were mounted on had some kind of semi conductive buildup on it shorting it to ground at some points thru the tuning range. Contact cleaner and compressed air eventually got it clean, and it now performs very well.
:::
:::
:::
::::Hello Again All,
:::
:::: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
::::
::::Thanks,
::::
::::Dave
:::::Hello All,
::::: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
::::: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
:::::
:::::Thanks,
:::::
:::::Dave
:::::
::::
:::
::
::Hi Dave-
::A couple of comments. First, unless there is a separate section on the tuning capacitor for each band, which would be unusual and require a REALLY long tuning cap, I'd discount that as part of the problem.
::I'd suspect silver-mica disease in the trimmer cap for this band. Two simple tests might reveal this. A) the noise is gone when the volume is turned down, and 2)tapping it makes it better or worse. Remember these are not definitive tests, but might help narrow the problem.
::Good luck,
::Terry
::
:
You may need to clean the spring contacts between the rotor shaft and the stator or fixed part of the tuning condenser. If these are not making clean contact it can cause static especially at higher frequencies.
Clifton
:Hello Again All,
: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
:
:Thanks,
:
:Dave
::Hello All,
:: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
:: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
::
::Thanks,
::
::Dave
::
:
So . . . that Zenith units produced audio with its 12 in speaker and P/P outputs impresses you . . . eh ? As per "silver mica" problems, I can only see that as being related to the insides of certain manufactured coil assemblies . . . particularly IF transformers . . . where a very thin silver paint/silk screening was applied to both sides of a mica disc. |
:
:Dave,
:
:You may need to clean the spring contacts between the rotor shaft and the stator or fixed part of the tuning condenser. If these are not making clean contact it can cause static especially at higher frequencies.
:
:Clifton
::Hello Again All,
:: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
::
::Thanks,
::
::Dave
:::Hello All,
::: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
::: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
:::
:::Thanks,
:::
:::Dave
:::
::
:
De-Ox-Id made by General Cement(now known as: GC Electronics) contains: Hepatane, Naptha (why that's in there I have no idea) and mineral oil. That's it, nothing else except C02 propellent. I knew about the detune effects. It's available in 4 oz spray cans for $7.00. I always used to like Trichlor. But it's not allowed to be used anymore. Would Isopropyl Alcohol be better on the mica trimmers?
I have been given more time on the Emerson. I just got two more radios in, including the 10-S-160. The owner of this set doesn't care if the shortwave works or not. I find this an interesting problem. I have never seen this before.
I'm finishing up the restoration of a 1950 Car Radio who's schematic wasn't released until 1958. Then I'll be back to the TV.
Thanks,
Dave
:
:
:
:
:
:
:
:
:
:
:
:
:Sir Dave. . . . .
:
:
:
:So . . . that Zenith units produced audio with its 12 in speaker and P/P outputs impresses you . . . eh ?
:
:
:
:" I sprayed the trimmers mounted on the tuning capacitor with De-Ox-Id. "
:
:
:
:I would say that was not the right thing to do . . . as we are assuredly talking about mica compresion trimmers . . .and that would not go well with the tuning stability with time onset, particularly the highest frequency trimmers..
:
:
:A solvents use would have washed out completely and been void of any residue.
:
:
:If you run a chemists standard initial evaluative test of a drop of De-Ox-It on a white blotter paper and completely dry it out you will ,for sure, notice the red coloring agent residue BUT additionally there will be an "oily" residue left. That being OK considering that you are working with a switch or controls contact or wiper element.
:
:
:So instead of your dry leaf plate- to air- to mica- to air- to other dry leaf plate, instead you are now setting up yourself with an
:dry leaf plate- to oil film- to mica- to oil film- to other dry leaf plate situation and the oil having to then dissipate with time.
:
:
:That shifts tuning.
:
:
:Plus, you KNOWS what havoc is wreaked with even a trace of water getting into a tuning / mica compression trimmer condenser. Whereupon, you then have to wait it out or cook it out.
:
:
:
:
:
:
:
:Aside . . . on De - Ox - It cleaner:
:
:
:I had a comm/crypto man assigned to me and my Strike team and at the start of operations and the end of operations Intelsums and Opsums had to go in as secure mode so I had to offer him extra back perimiter security and he would always have to initially clean his code wheels.
:Somehow, I am 99 and 86/100th percent convinced that 16 ounce bottle of cleaner he was always using was De-Ox-IT, just by my remembering its odor and that red coloring agent also used. Remembering the color, because, somewhat lint free, pure WHITE twill jean cleaning cloths were used.
:
:
:Also,rememnbering it so well, because in order to get set up quickly, I usually helped him set up. I also wondered if we coerced the Navy to be supplying that twill cloth, as it was just like their dress whites materiel.
:
:
:Now if I just had that FSN . .stock number . .and ANY surplus was coming up available, that 16 ounces would translate into $100 of liquid at the rate that De Ox It is charging for their small vial sizes.
:
:
:
:As per "silver mica" problems, I can only see that as being related to the insides of certain manufactured coil assemblies . . . particularly IF transformers . . . where a very thin silver paint/silk screening was applied to both sides of a mica disc.
:
:
:That assures a uniform contact areas on both sides to be then relying upon their outward connectivity then being made to pressured contact strips. With time and chemical transitioning the silver blackens into silver oxide and along with there additionally being dissimilar metals connected, the interfacing connection further deteriorates.
:
:
:Airborne/humidity carried reactants further aggravate the situaton.
:
:
:You don't even have that situaton with your single sheet(s) of mica dielectric.
:
:
:As far as your single sheet of mica between the plates, the only thing imaginable with that is a metal burr damaging its integrity, a crease or a pinhole . And yet another rare situation is an ore contaminant occuring within the vein of a sheave of the raw mica materiel.
:
:
:THAT conditon would and should have been caught during a HV Hi-POT test, of the incoming sheet mica at manufacturings initial materiel QC.
:
:
:Thassit . . . .Got the clients Emerson Tee Wee linear again ? . . its fast become your self imposed June the 30th PLUS.
:
:
:
:
:
: 73's de Edd
:
:
:
:
:
:
:
:
:
:
:
::Dave,
::
::You may need to clean the spring contacts between the rotor shaft and the stator or fixed part of the tuning condenser. If these are not making clean contact it can cause static especially at higher frequencies.
::
::Clifton
:
:
:
::
:::Hello Again All,
::: I tried another 6A8 and it does the same thing. Maybe a mica capacitor isn't working?
:::
:::Thanks,
:::
:::Dave
:
:
::::Hello All,
:::: This symptom sounds similar to plates touching. But there doesn't seem to be anything wrong with the tuning capacitor at all. The A Band works perfectly. Anyway, as I tune past about 6.5 Mc I can hear something like slow motor-boating (tick-tick-tick-tick,etc.). It does get a little faster in places as I tune through the band. If I tap the tuning capacitor it stops momentarily. It does this a tiny bit on the B band but it can tune in stations there. Then after about 10 Mc on the C band the tuning sounds scratchy but it can tune in nothing. There is no motor-boating up there. Could the converter tube be having trouble with higher frequencies?
:::: All paper and electrolytic capacitors have been replaced. The sound is amazing on this radio.
::::
::::Thanks,
::::
::::Dave
::::
:::
::
: