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Still new at this and new to Philco and superhets. Is it necessary to pull the coils out to test them? I haven't found a definitive answer in my research. Is there a cheat sheat available showing point to point testing that would verify continuity in all the coils w/o disturbing them. Thanks in advance. One curious thing I found was a single 16 mfd ecap instead of the 2 8mfds...probably a repair??? No stations as yet and I replaced the 16 mfd with a 22 mfd.
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Most of the time the primary of the antenna coil and the feedback winding of the oscillator coil are the one that are commonly open.
Terry
(This post was last modified: 02-27-2012, 08:57 PM by
Radioroslyn.)
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(02-27-2012, 08:56 PM)7estatdef Wrote: Most of the time the primary of the antenna coil and the feedback winding of the oscillator coil are the one that are commonly open.
Terry
The only sound I get is steady soft hum and a noise like somebody is hitting radio with a rope at a steady cadence...curious.
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Go a head and replace the paper caps, electrolytic caps and out of spec resistors. Then we can talk about coils.
Terry
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After recapping the bakelites and rewinding the primary of the osc coil...still nothing in terms of reception. Primary of osc coil now measures 2.1 ohms vs. 3.4 of schematic. Antenna on grid cap of 6A7...still nothing. The .7 SW of antenna coil measures open. Would that knock out even BC reception??
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(03-19-2012, 08:39 AM)sjhs1962 Wrote: After recapping the bakelites and rewinding the primary of the osc coil...still nothing in terms of reception. Primary of osc coil now measures 2.1 ohms vs. 3.4 of schematic. Antenna on grid cap of 6A7...still nothing. The .7 SW of antenna coil measures open. Would that knock out even BC reception??
It is customary to post link to schematic with question
http://www.nostalgiaair.org/PagesByModel...013793.pdf
If the antenna coil is open, it needs to be rewound or replaced. That being said and if voltages are reasonable, work backwards from the speaker (right to left) with a modulated signal generator to find out where you are losing signal.
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If the primary of the ant coil as open you can hook the ant to the grid cap of the mixer tube and you should be able to receive radio signals. Is you local oscillator working?
Terry
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(03-19-2012, 04:33 PM)7estatdef Wrote: If the primary of the ant coil as open you can hook the ant to the grid cap of the mixer tube and you should be able to receive radio signals. Is you local oscillator working?
Terry
http://www.philcoradio.com/tech/60evol.htm
No, oscillator not working. In addition plate voltages are high 370 vdc. Also, resistor on band switch measures 11 ohms ...schematic says 10k, but I have another 60 in a different version that works and this resistor also measures 11 ohms. Confused. Antenna on grid cap of 6A7 doesn't bring in anything.
(This post was last modified: 03-19-2012, 08:52 PM by
sjhs1962.)
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Your resistor measures 11 Ohm because it is in parallel to the antenna coil that actually says "11 Ohm" on it.
You know how paralleling resistors work, right?
(This post was last modified: 03-19-2012, 09:15 PM by
morzh.)
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(03-19-2012, 09:14 PM)morzh Wrote: Your resistor measures 11 Ohm because it is in parallel to the antenna coil that actually says "11 Ohm" on it.
You know how paralleling resistors work, right?
Thanks...tricky concept that could trip you up easily. I found the calculator online...of course you have to know that the resistors are in parallel.
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(03-19-2012, 09:44 PM)sjhs1962 Wrote: ...of course you have to know that the resistors are in parallel.
That's where experience in reading and interpreting a schematic helps with these kinds of issues.
Continued good luck,
Chuck
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Well The thing isn't gonna work if the oscillator isn't running. Check the voltage on grid 2 of the 6A7. Should be pretty high like 100 volts. If not rewind oscillator feedback winding.
Terry
(This post was last modified: 03-21-2012, 06:21 PM by
Radioroslyn.)
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And make sure that oscillator feedback winding is wound counterclockwise!
--
Ron Ramirez
Ferdinand IN
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Osc coil wire that doesn't go to any terminals on actual osc coi....what is purpose of this coil wire? Does it go to cathode of 6A7?
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On the antena coil, the primary is the inserted coil inside the tube and the secondary has the three taps. I am wondering if it is necessary to rewind the .7 sw coil since it doesn't function for the most part?
