160m Mods: Difference between revisions
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1. the input PI section, |
1. the input PI section, |
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2. the PA output PI section |
2. the PA output PI section |
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3. changing one of the bandswitch |
3. changing one of the bandswitch stops. |
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It's a tight fit inside the input circuit compartment. 160m variable coil is bottom left. The other 160m coil and SM caps are tucked inside the aluminum box. |
It's a tight fit inside the input circuit compartment. 160m variable coil is bottom left. The other 160m coil and SM caps are tucked inside the aluminum box. |
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NB. It appears there are two different 30S1 input circuits depending on the age of the amp. The 160m mod is practical only for input circuits using simple wafers with contacts on one side only. If there is a grounding ring in addition to a selector ring then things get rather complicated. The mod I am doing does not deal with the double sided grounding wafers for obvious complex fabrication reasons. |
NB. It appears there are two different 30S1 input circuits depending on the age of the amp. The 160m mod is practical only for input circuits using simple wafers with contacts on one side only. If there is a grounding ring in addition to a selector ring then things get rather complicated. The mod I am doing does not deal with the double sided grounding wafers for obvious complex fabrication reasons. |
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Collins uses 1KV disk ceramic so ideally the 160m capacitors should be 1 KV SM but space is tight. I tested the 500V SMs i am using and they showed no leakage up to 1.5KV, the max range on the 576 Tek curve tracer, so they should be ok up to 100W. I noticed Alpha 77Sx uses compression micas, which have higher Q than ceramics. |
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[[File:Schem.jpg|500px|thumb|center|Schematic showing 160m additions to the PA]] |
[[File:Schem.jpg|500px|thumb|center|Schematic showing 160m additions to the PA]] |
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[[File:Input_pi_160.jpg|500px|thumb|center|160m addition to the input-Pi circuit]] |
[[File:Input_pi_160.jpg|500px|thumb|center|160m addition to the input-Pi circuit]] |
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[[File:160m_ouptput_PA.jpg|500px|thumb|center|Accessing the rear PA band wafer for removal]] |
[[File:160m_ouptput_PA.jpg|500px|thumb|center|Accessing the rear PA band wafer for removal]] |
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Revision as of 02:12, 27 May 2020
160m Mods. The 160m mods involve working on: 1. the input PI section, 2. the PA output PI section 3. changing one of the bandswitch stops.
It's a tight fit inside the input circuit compartment. 160m variable coil is bottom left. The other 160m coil and SM caps are tucked inside the aluminum box.
NB. It appears there are two different 30S1 input circuits depending on the age of the amp. The 160m mod is practical only for input circuits using simple wafers with contacts on one side only. If there is a grounding ring in addition to a selector ring then things get rather complicated. The mod I am doing does not deal with the double sided grounding wafers for obvious complex fabrication reasons.
Collins uses 1KV disk ceramic so ideally the 160m capacitors should be 1 KV SM but space is tight. I tested the 500V SMs i am using and they showed no leakage up to 1.5KV, the max range on the 576 Tek curve tracer, so they should be ok up to 100W. I noticed Alpha 77Sx uses compression micas, which have higher Q than ceramics.
- Switch-Wafer modifications
