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 Post subject: More questions about Delco R-1130...
PostPosted: Jul Tue 10, 2018 12:53 am 
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Does anybody know what kind of speaker a Delco R-1130 has? Permanent magnet or ? I'm offered one but the speaker is missing.


Last edited by guyonearth on Aug Fri 10, 2018 4:36 am, edited 1 time in total.

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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Tue 10, 2018 12:59 am 
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http://www.nostalgiaair.org/pagesbymode ... 022576.pdf

looks like Electromagnetic.

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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Tue 10, 2018 4:55 am 
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I couldn't really tell from that schematic, but thanks.


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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Tue 10, 2018 5:15 am 
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Definitely an electromagnet. The field coil serves as the filter choke in the B+ supply.

Jay


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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Tue 10, 2018 9:46 am 
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Radiomuseum entry for The Commentator model:

https://www.radiomuseum.org/r/united_1_delco_r1130.html

"Loudspeaker:Electro Magnetic Dynamic LS (moving-coil with field excitation coil)"

Note that the tube list has a minor error: the first audio amp tube should be a 6F5, not a 6F6.


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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Tue 10, 2018 9:51 pm 
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JnTX wrote:
Definitely an electromagnet. The field coil serves as the filter choke in the B+ supply.

Jay


Wonder what the resistance of that coil is?


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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Tue 10, 2018 10:26 pm 
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guyonearth wrote:
JnTX wrote:
Definitely an electromagnet. The field coil serves as the filter choke in the B+ supply.

Jay


Wonder what the resistance of that coil is?

Probably around 1000-1500 ohms

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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Tue 10, 2018 10:27 pm 
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guyonearth wrote:
JnTX wrote:
Definitely an electromagnet. The field coil serves as the filter choke in the B+ supply.

Jay


Wonder what the resistance of that coil is?

Looks like 55 volts is dropped across the field coil. So, if the B+ current used by the radio is 75 mA, the field coil resistance will be in the neighborhood of 730 ohms. But that's based on a guess of 75 mA as representative for this type of set- could be more, or less.


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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Tue 10, 2018 10:31 pm 
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lorenz200w wrote:
guyonearth wrote:
JnTX wrote:
Definitely an electromagnet. The field coil serves as the filter choke in the B+ supply.

Jay


Wonder what the resistance of that coil is?

Looks like 55 volts is dropped across the field coil. So, if the B+ current used by the radio is 75 mA, the field coil resistance will be in the neighborhood of 730 ohms. But that's based on a guess of 75 mA as representative for this type of set- could be more, or less.

That was my 1st guess, but they're not giving us the DC voltage out of the rectifier.....the 285 is the a.c. voltage on the plates

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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Wed 11, 2018 3:11 am 
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The radio I have is missing the speaker. I could try using an 8" electrodynamic I have from that era, or using a modern speaker. Not sure how to approach it.
EDIT: May have a line on a 12" speaker from another radio, 1000 ohm coil.


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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Wed 11, 2018 4:07 am 
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guyonearth wrote:
The radio I have is missing the speaker. I could try using an 8" electrodynamic I have from that era, or using a modern speaker. Not sure how to approach it.
EDIT: May have a line on a 12" speaker from another radio, 1000 ohm coil.

If you use the electro-dynamic one... the field coil may be about the same... but the print also shows a hum-bucker coil as part of the original speaker... so you'll need to examine how those wires connect if the substitute speaker doesn't have a hum-bucker.

You can use a modern PM speaker and substitute a resistor in place of the field coil ... however the ripple-smoothing won't be as good, so you'll need to increase the size of the second filter capacitor to compensate,.

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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Wed 11, 2018 2:47 pm 
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Pbpix wrote:
guyonearth wrote:
The radio I have is missing the speaker. I could try using an 8" electrodynamic I have from that era, or using a modern speaker. Not sure how to approach it.
EDIT: May have a line on a 12" speaker from another radio, 1000 ohm coil.

If you use the electro-dynamic one... the field coil may be about the same... but the print also shows a hum-bucker coil as part of the original speaker... so you'll need to examine how those wires connect if the substitute speaker doesn't have a hum-bucker.

You can use a modern PM speaker and substitute a resistor in place of the field coil ... however the ripple-smoothing won't be as good, so you'll need to increase the size of the second filter capacitor to compensate,.


That would have to be a pretty big resistor, right?


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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Wed 11, 2018 3:17 pm 
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Define "big"......suppose you use 1000 ohms and the current is 70mA. Power = 0.07^2 * 1000 =~5 watts
Use a part rated at 10 watts, and bolt it or glue it to the chassis or speaker frame.

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 Post subject: Re: Speaker setup is in a Delco R-1130?
PostPosted: Jul Wed 11, 2018 11:56 pm 
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guyonearth wrote:
Pbpix wrote:
guyonearth wrote:
The radio I have is missing the speaker. I could try using an 8" electrodynamic I have from that era, or using a modern speaker. Not sure how to approach it.
EDIT: May have a line on a 12" speaker from another radio, 1000 ohm coil.

If you use the electro-dynamic one... the field coil may be about the same... but the print also shows a hum-bucker coil as part of the original speaker... so you'll need to examine how those wires connect if the substitute speaker doesn't have a hum-bucker.

You can use a modern PM speaker and substitute a resistor in place of the field coil ... however the ripple-smoothing won't be as good, so you'll need to increase the size of the second filter capacitor to compensate,.


That would have to be a pretty big resistor, right?

Not really.

An AA5 radio typically draws about 50ma.
If the resistor was 1200 ohms:
that would drop 60 volts.
P=IxE
.05A x 60 = 3 watts

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 Post subject: Re: More questions about Delco R-1130...
PostPosted: Aug Fri 10, 2018 4:39 am 
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I'm adding this in here because I've been told not to do multiple posts on the same radio. This radio is up and running, but the eye tube never closes, or even seems to move. (Yes, I have checked the 1 meg resistor in the socket, and it's fine). The radio seems fairly deaf overall, but it does pick up a number of local stations, at least as many as some other radios I have. Anybody have any ideas?


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 Post subject: Re: More questions about Delco R-1130...
PostPosted: Aug Fri 10, 2018 11:52 am 
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Have you done an alignment?

Do you see a change in the AVC voltage when you tune in a station?

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 Post subject: Re: More questions about Delco R-1130...
PostPosted: Aug Fri 10, 2018 3:26 pm 
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pixellany wrote:
Have you done an alignment?

Do you see a change in the AVC voltage when you tune in a station?


It's peaked as best as I could get it. I'm honestly not sure where to check AVC, the schematic is pretty minimal.


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 Post subject: Re: More questions about Delco R-1130...
PostPosted: Aug Fri 10, 2018 6:22 pm 
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guyonearth wrote:
pixellany wrote:
Have you done an alignment?

Do you see a change in the AVC voltage when you tune in a station?


It's peaked as best as I could get it. I'm honestly not sure where to check AVC, the schematic is pretty minimal.

You can check it at the grid node of the magic eye tube. All the eye tube does is serve as a high-impedance, relative-indicating DC voltmeter that monitors the AVC bus voltage. However, to obtain meaningful results you will need to measure it with an extremely high-impedance voltmeter (vacuum-tube voltmeter) or an oscilloscope; otherwise you will load down the AVC bus and obtain unusable readings.

"Peaked as best as I could get it" is a pretty open-ended statement. Does that mean that the IF filters didn't have sharp peaks? If you can't get sharp peaks out of all of the filter adjustments, reception will be poor and there won't be enough demodulated signal to charge the AVC cap.

If you have doubts about the eye tube operation, you can put three 1.5v AA cells in series and tie the + lead to chassis ground; then clip the negative lead to the eye tube grid (pin 3). (Use caution when doing this, of course, since you will be exposing yourself to high voltages.) This will put a large enough negative voltage on the eye tube grid to drive it into significant closure. No closure= something is wrong with the eye tube. If you messed with the eye tube socket internals, check to make sure that the B+ wire goes to pin 4 and not pin 2. If you had to replace the 1 Meg resistor inside the tube socket that links pin 2 and pin 4, it's easy to re-install the B+ wire on pin 2 instead of pin 4. If this has been done, the tube will fluoresce but the shadow aperture won't budge.


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 Post subject: Re: More questions about Delco R-1130...
PostPosted: Aug Sat 11, 2018 5:39 am 
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lorenz200w wrote:
guyonearth wrote:
pixellany wrote:
Have you done an alignment?

Do you see a change in the AVC voltage when you tune in a station?


It's peaked as best as I could get it. I'm honestly not sure where to check AVC, the schematic is pretty minimal.

You can check it at the grid node of the magic eye tube. All the eye tube does is serve as a high-impedance, relative-indicating DC voltmeter that monitors the AVC bus voltage. However, to obtain meaningful results you will need to measure it with an extremely high-impedance voltmeter (vacuum-tube voltmeter) or an oscilloscope; otherwise you will load down the AVC bus and obtain unusable readings.

"Peaked as best as I could get it" is a pretty open-ended statement. Does that mean that the IF filters didn't have sharp peaks? If you can't get sharp peaks out of all of the filter adjustments, reception will be poor and there won't be enough demodulated signal to charge the AVC cap.

If you have doubts about the eye tube operation, you can put three 1.5v AA cells in series and tie the + lead to chassis ground; then clip the negative lead to the eye tube grid (pin 3). (Use caution when doing this, of course, since you will be exposing yourself to high voltages.) This will put a large enough negative voltage on the eye tube grid to drive it into significant closure. No closure= something is wrong with the eye tube. If you messed with the eye tube socket internals, check to make sure that the B+ wire goes to pin 4 and not pin 2. If you had to replace the 1 Meg resistor inside the tube socket that links pin 2 and pin 4, it's easy to re-install the B+ wire on pin 2 instead of pin 4. If this has been done, the tube will fluoresce but the shadow aperture won't budge.


The IF filters have pretty sharp peaks. I will try some tests on the tube later. I may have another tube, I have to look.


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