Philco RF choke bad..ok to replace with resitor?

12/27/2010 8:09:46 PMGeorge

I am recapping a Philco model 665 and the RF choke is bad. On the schematic it is #22 at 160ohms... Is it ok to replace this with a resistor say at a 1/2 watt? If so why did they not so this in the first place? Cheaper?

12/27/2010 8:13:31 PMGeorge..oops also

:I am recapping a Philco model 665 and the RF choke is bad. On the schematic it is #22 at 160ohms... Is it ok to replace this with a resistor say at a 1/2 watt? If so why did they not so this in the first place? Cheaper? ALSO I ONLY HAVE 150 OHM @1/2 watt..will that work?
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12/27/2010 10:54:42 PMThomas Dermody

I am trying to decipher the schematic. At this point I have yet to figure out exactly what the choke does, but it is connected between the broadcast and long wave switch contacts, most likely part of the 1st RF interstage transformer system.

Chokes are usually more expensive than resistors. If a choke is in place, it has a purpose, especially in the RF section. Philco made a lot of cheap radios, but they also made a lot of good radios, and when extra parts were put in place, they served a good purpose. I would repair or replace the choke. If it has opened, unwind it and count the number of turns. Rewind with same size wire and turn count.

Meanwhile I will continue to study the schematic. It does not help that Google Chrome has made it impossible for me to view these files with Adobe, but instead with Google's own program, which doesn't allow for rotation of the picture, so I will have to re-open it in Internet Explorer.

12/27/2010 11:40:28 PMEdd

Sir George ? . . . . .

Just as its "choke" assigned designation implies, its circuit function in this sets related circuitry is to " choke "

the developed RF present in that RF amps plate circuitry on the two lowest bands and and hold it back from taking

its passage straight thru the low impedance path to ground via the power supply.

Yet . . . the power supply DC inflow to the circuitry is unimpeded.

Sooooo a resistor won't equally fill the bill in that respect.

That 160 ohm resistance figure must be tied to even more inductive value than a common ~ 2.5Mh inductance, as that

is being typically around 75 ohms for a coil to be utilized at that stages low level of current consumption.

Have you initially attempted an examination . . . . under a HIGH INTENSITY light and MAGNIFIER . . . . of the wiring

coming out from the choke coil windings start and finish ?

I'm hoping for you to see an errosive copper sulfate deposit, with the wire eaten open.

Then hoping that you can repair the open circuit ? Particularly if its being the outer finish end of the winding.

73's de Edd

:I am trying to decipher the schematic. At this point I have yet to figure out exactly what the choke does, but it is connected between the broadcast and long wave switch contacts, most likely part of the 1st RF interstage transformer system.
:
:Chokes are usually more expensive than resistors. If a choke is in place, it has a purpose, especially in the RF section. Philco made a lot of cheap radios, but they also made a lot of good radios, and when extra parts were put in place, they served a good purpose. I would repair or replace the choke. If it has opened, unwind it and count the number of turns. Rewind with same size wire and turn count.
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:Meanwhile I will continue to study the schematic. It does not help that Google Chrome has made it impossible for me to view these files with Adobe, but instead with Google's own program, which doesn't allow for rotation of the picture, so I will have to re-open it in Internet Explorer.
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:T.
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12/28/2010 12:01:28 AMunwound choke...george

I unwound the choke about 1/4 of the way into it and wire was broke...I am having a hell of a time re-finding the break on the coil...Ok ..I guess I have to restore the choke...

12/28/2010 4:04:43 AMGeorge...repaired

The choke was wire was broke 1/2 way into the windings..fixed and rewound....Anyway..all test good but i am not recieving ANY signal on this Philco 665 unit..Back to the bench and a checking of all resistors and other coils...

:I unwound the choke about 1/4 of the way into it and wire was broke...I am having a hell of a time re-finding the break on the coil...Ok ..I guess I have to restore the choke...
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