There's a 2-watt 4000 ohm, now reads 6.66K, connected between the postive of C10 8 MFD and Pin 2 of the RF 6D6. I can tell it's an add on. Any purpose you figure or just a bad mistake.

Bill VA

http://www.nostalgiaair.org/PagesByModel/379/M0023379.pdf

I am too new to these old designs and am not familiar with that RF circuit as it concerns T2.
.. looks like that resistor is in parallel with both sections of T2 primary that normally supplies B+ to the 6d6 plate.
My first thought was that it is alternatively supplying B+ if T2 primary was open.

But I don't know how T2 would function if bypassed due to an open.

Have you tried removing the resistor to test if the radio still works? ....and see that you still get B+ on the 6D6 plate?

Norm probably can enlighten us here.

Hi, Bill. Hmmm. Pin 2 of the 6D6 is the plate.

I wonder if all or part of the primary winding of T2 is open, and somebody bypassed it with a resistor. Just a theory.

Does the radio play?

Doug

:There's a 2-watt 4000 ohm, now reads 6.66K, connected between the postive of C10 8 MFD and Pin 2 of the RF 6D6. I can tell it's an add on. Any purpose you figure or just a bad mistake.
:
:Bill VA
:
:http://www.nostalgiaair.org/PagesByModel/379/M0023379.pdf

Either what they say, or maybe there was a serious problem that the owner/repairman was trying to fix, such as oscillation, or distortion on local stations. For the latter, the resistor connected as you say, is the wrong way to go about it, but who knows. Actually, for both situations, the resistor is the wrong way to go about it.

T

:Either what they say, or maybe there was a serious problem that the owner/repairman was trying to fix, such as oscillation, or distortion on local stations. For the latter, the resistor connected as you say, is the wrong way to go about it, but who knows. Actually, for both situations, the resistor is the wrong way to go about it.
:
:T

Of, course, the first thing to do is remove the resistor and see what happens. If there is an open winding in one of the coils, putting B+ on the plate of the RF tube might cause some RF to get to the converter and work on strong stations, but then, "iitrwtgai" (didn't feel like typing it again) In some of these "repairs" you run across, one can only scratch one's head and wonder.
Lewis L.

A resistor across the primary will lower the circuit "Q" factor, in turn reducing the selectivity of the 1st RF stage and the set. Some sharp techie or rebuiler of yesteryear may have done it to reduce the net RF gain or stop the 1st RF from oscillating or because of a strong local station overloading everything.

marv

:There's a 2-watt 4000 ohm, now reads 6.66K, connected between the postive of C10 8 MFD and Pin 2 of the RF 6D6. I can tell it's an add on. Any purpose you figure or just a bad mistake.
:
:Bill VA
:
:http://www.nostalgiaair.org/PagesByModel/379/M0023379.pdf

Hi Bill

Since it's not shown on the schematic I would think the primary of T2 is open and somebody bypassed the winding? If the manufacturer made a modification they wouldn't have used a 2 watt resistor across the coil. The coil would carry most of the current.

If it was used to bypass an open winding a small cap (50-100pf) from plate of RF 6D6 to 6C6 may help reception?

Norm

:There's a 2-watt 4000 ohm, now reads 6.66K, connected between the postive of C10 8 MFD and Pin 2 of the RF 6D6. I can tell it's an add on. Any purpose you figure or just a bad mistake.
:
:Bill VA
:
:http://www.nostalgiaair.org/PagesByModel/379/M0023379.pdf

:Hi Bill
I also concur on the strong possibility of the unit having been a shunt for that IF transformers with an open primary.

Upon computing the operation of that tube, with a tuning off station or into a weak station, that "plate" resistor could be dissipating ~2.75 watts, whereas on a strong station it could only require ~1.1 watts consumption, in response
to the AVC levels compensatory shift. Your finger tip on the resistor after an adequate warmup period sholud confirm that, or the shunting of it with a DC voltmeter for a quick reading would also confirm...if you are antsy.

Now if it was designed in as a "Q" dampener or bandwith enhancing modification, it would merely / typically have but a 1/2 watt unit value, since the coil winding that is shunting is carrying all of the power (99.86/100) in a low RF level application,such
as this would be. .
(10K ohm and 5 /4.7 k ohm are very common choices for damping resistors)

Sooooooo we are all like that Dirty Harry movie..with its Magnum pistol and the query... "We (I) gots to know"

So lift out the resistor and see if there IS an intact IF tranfo winding present ...if SO, that was one ratty tolerance resistor !
And hopefully, after pulling off the shield, if the tranfo was open, it will be accessible at the start or the end of its winding and you can repair its continuity and get some greatly enhanced performance from that unit.

73 de Edd

::Hi Bill
:I also concur on the strong possibility of the unit having been a shunt for that IF transformers with an open primary.
:
:Upon computing the operation of that tube, with a tuning off station or into a weak station, that "plate" resistor could be dissipating ~2.75 watts, whereas on a strong station it could only require ~1.1 watts consumption, in response
:to the AVC levels compensatory shift. Your finger tip on the resistor after an adequate warmup period sholud confirm that, or the shunting of it with a DC voltmeter for a quick reading would also confirm...if you are antsy.
:
:Now if it was designed in as a "Q" dampener or bandwith enhancing modification, it would merely / typically have but a 1/2 watt unit value, since the coil winding that is shunting is carrying all of the power (99.86/100) in a low RF level application,such
:as this would be. .
:(10K ohm and 5 /4.7 k ohm are very common choices for damping resistors)
:
:Sooooooo we are all like that Dirty Harry movie..with its Magnum pistol and the query... "We (I) gots to know"
:
:So lift out the resistor and see if there IS an intact IF tranfo winding present ...if SO, that was one ratty tolerance resistor !
:And hopefully, after pulling off the shield, if the tranfo was open, it will be accessible at the start or the end of its winding and you can repair its continuity and get some greatly enhanced performance from that unit.
:
:73 de Edd

Well I want to thank everyone for their help. I had not tried the set yet. I had just been going over it and noting things of interest, i. e., power transformer ok, candohm bad, loose wires, etc. It does not have a speaker. An output transformer has been put under the chassis and it is wired right. Have not located anything wired in for the field coil L1.

But to T2. I checked it today and the primary is open, all the way. I went ahead and pulled it today because I saw a paper cap on the inside. It's a .006 and wired so as to connect the grid of the 6C6 and the plate of the 6D6. So it's get out my 7X time. I have a heck of time with the small wire nowadays. Thanks again. As always remarkable help here.

Bill VA