Dropping Resistor?
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Dropping Resistor?
Looking at the schematic on the tube line up a 12BA6 could be used or a 6BJ6 as the RF amp.
In between the heater line up is a 3 watt 33 ohm resistor. With the 12BA6 in the line the ac voltages add up to a 114 volts without the drooping resistor. Do you still need the dropping resistor when the 12BA6 is used? I can see it is needed when the 6 volt tube is used because the string would only be up to 108 volts, but not with the 12BA6 is used.
In between the heater line up is a 3 watt 33 ohm resistor. With the 12BA6 in the line the ac voltages add up to a 114 volts without the drooping resistor. Do you still need the dropping resistor when the 12BA6 is used? I can see it is needed when the 6 volt tube is used because the string would only be up to 108 volts, but not with the 12BA6 is used.
nytuberadio- New Member
- Number of posts : 11
Registration date : 2010-07-26
Re: Dropping Resistor?
Assuming this is a series-connected AC/DC set, I'd leave the resistor as it should be.
It takes up excess surge voltage/current during warmup.
It takes up excess surge voltage/current during warmup.
repairtech- Member
- Number of posts : 97
Registration date : 2010-04-28
Re: Dropping Resistor?
repairtech does have a point.
However, I have worked on Zenith H723 radios. These come in types with 6BJ6 and 12BA6 as the RF tube. H723's that have the 6BJ6 always have the resistor and H723 that have the 12BA6 never have the resistor.
My tendancy is to go with the Zenith engineers' design, however, repairtech does have a point. Reasonable persons can disagree on this.
All the Best,
Bill
However, I have worked on Zenith H723 radios. These come in types with 6BJ6 and 12BA6 as the RF tube. H723's that have the 6BJ6 always have the resistor and H723 that have the 12BA6 never have the resistor.
My tendancy is to go with the Zenith engineers' design, however, repairtech does have a point. Reasonable persons can disagree on this.
All the Best,
Bill
zdiode- New Member
- Number of posts : 3
Registration date : 2012-01-03
Re: Dropping Resistor?
Yes leave the dropping resistor in place.They put it there to help keep voltage where they wanted it.
Sprman
Sprman
sprman- Member
- Number of posts : 323
Age : 66
Registration date : 2008-03-27
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