S.O.S. Electronics Scout 20 Amplifier help

[Alabama Trainman]

I'm looking for the value of the RF choke on the upper deck. I took a pic of the part from another amp but need to replace the one in a different Scout 20 that burnt up. I searched everywhere and could not find a schematic.

 

[brandon7861]

It looks like a non-ferrite support, so chances are an air would coil calc would get you reasonably close. Why not just wind one with the same number of turns on the same diameter form with the same diameter wire?

 

[Alabama Trainman]

It looks like a non-ferrite support, so chances are an air would coil calc would get you reasonably close. Why not just wind one with the same number of turns on the same diameter form with the same diameter wire?

Because I don't have the materials. Looking for the mH value to purchase a new one. Thanks.

 

[brandon7861]

Because I don't have the materials. Looking for the mH value to purchase a new one. Thanks.

I counted 90 turns. If you can tell me the form diameter and the wire gauge, I can figure it out.

 

[brandon7861]

Based on the picture... (a guess that it's 20awg and 1/4" diameter), about 4.8uH. I'd bet it's a standard value 4.7uH.

 

[nomadradio]

That would be microhenries (uH), not millihenries mH.

The old Ohmite Z28 choke would work fine. I'm hesitant to use less than around 22 uH, but some amplifiers get by with less.

Had a look at RF Parts. Not much to see in this category there.

73

 

[linearone]

That would be microhenries (uH), not millihenries mH.

The old Ohmite Z28 choke would work fine. I'm hesitant to use less than around 22 uH, but some amplifiers get by with less.

Had a look at RF Parts. Not much to see in this category there.

73

Is that choke part of a feedback circuit?

 

[Alabama Trainman]

Is that choke part of a feedback circuit?

21uH is what it is. Z-28

 

[nomadradio]

Is that choke part of a feedback circuit?

No.

It's the plate choke, or "anode choke" for purists. It does two things. Provides a low-resistance path for DC current from the HV power supply to the tubes' plate circuit. Second, it blocks the flow of RF current that would otherwise feed back into the HV power supply.

73

 

[linearone]

No.

It's the plate choke, or "anode choke" for purists. It does two things. Provides a low-resistance path for DC current from the HV power supply to the tubes' plate circuit. Second, it blocks the flow of RF current that would otherwise feed back into the HV power supply.

73

Tiny dang

 

[linearone]

I'm looking for the value of the RF choke on the upper deck. I took a pic of the part from another amp but need to replace the one in a different Scout 20 that burnt up. I searched everywhere and could not find a schematic.

If it's a simple plate choke for a cb amp it easily home brewed. See if you can borrow an inductance meter

 

[Alabama Trainman]

Z-28 ohmite chokes are readily available. It would be easier to just replace it. If it was a part that was unobtainable, then I would fabricate my own. Thank you all for your input. The actual value is now known for me to carry on. 73's