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Manufacturer of Ultra High Quality Audio Transformers
Introduction
Input (and DC-free line output)
applications
Plate (anode) chokes,
interstage and line output
Push-Pull and SE
Chokes
for Power Supply
Mains transformers
Miscellanious products
Some Pictures
Storage
| These Lundahl C-core products are also based on the double Coil technology,
which gives options that are not possible with single coils. The coils
can be put in series or in parallel, resulting in two different valuesl.
Also, each coil can be separately used, giving higer Commnon Mode
Rejection than normal (Single Coil) chokes. So, this
gives three applications for each choke type.
Here is an example for the 1673/10. This product has two coils of each 5Henry, 200mA 1) Both coils in series: Gives 10Henry / 200mA
In the double coil configuration, one coil is in the positive lead to the second capacitor, and one on the ground lead to the second capacitor. This will give lowest field radiation coming from the choke. Such good results can not be achived with lower cost E-Core chokes, and the Lundahl double coil chokes are a major step into the direction of a really hum-free amplifier. The datasheets gives a good diagram of how to connect a double coil choke, using it's full features and get best noise rejection from it. (check for instance here, all at the bottem of the last page) Of course, it is still possible to use them as a single coil also. |
Overview of types
| 1 ) LL1638 | Wound with thick wire. Gives best performance for High Current applications. Available with different air gaps, which results in different current / henry. |
| 2) LL1673 | Same as above, but wound with thin wire. Gives best performance for High Henry applications. |
| 3) LL1685 | Same as 1673, but wound on the next smaller core. Lower in price, but less Henry. |
| Note: | At "medium" current, many combinations can be made, but some chokes will perform better than others. In the following table, the best combinations are given, with the most Henry for the money, at a several currents. |
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POWER CHOKES, BEST COMBINATIONS |
DC-mA Important: Read Note below! |
Henry
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for lower current, use LL1667 /25mA |
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168
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Coils in Series. LL1685= Compact construction. |
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17
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Coils in Series. LL1673= High Henry type. |
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20
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Coils in Series. LL1685= Compact construction. |
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13
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Coils in Series. LL1673= High Henry type. |
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15
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Coils in Series. LL1685= Compact construction. |
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10
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Coils in Series. LL1673= High Henry type. |
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10
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Coils in Parallel. LL1685= Compact construction. |
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3,25
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Coils in Parallel. LL1673= High Henry type. |
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3,75
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Coils in Parallel. LL1685= Compact construction. |
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2,5
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Coils in Series. LL1638= High Current Type. |
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4
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Coils in Parallel. LL1638= High Current Type. |
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1
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DC-mA is specified very conservatively by Lundahl, at FULL specified ripple voltage over the choke. This will only happen when you work without first capacitor (is possible with Lundahl chokes) When working with a first capacitor, the DC-mA current can be exceeded with ca 10..15% ! |
SOME DESIGN RULES FOR A HUM-FREE TUBE RECTIFIER CIRCUIT
In this circuit diagram the primary Capacitor is C1, the secondary
Capacitor is C2.
