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Vyper 14 Chassis

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#26 Jeff Morgan

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Posted 04 June 2020 - 02:45 PM

I think you would really like the PVS-14, regardless if you adapt it or not. The gain pot is so much better on it than on the mod-3, like a fine audio knob on a high fidelity sound system. 

 

Are the pots dimensionally close?

 

How involved of a DIY would that be for Mod 3 owners?



#27 cnoct

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Posted 05 June 2020 - 03:36 AM

Are the pots dimensionally close?


MOD-3C Trimmer/Pot:

~ 13.8mm body diameter
~ 11.5mm body length

PVS-14 Trimmer/Pot:

~ 12.7mm body diameter
~ 9.5mm body length
 


How involved of a DIY would that be for Mod 3 owners?

Sorry, not sure what the DIY is?!

 

Transplanting the tube from a MOD-3 over to a PVS-14 or ???



#28 Jeff Morgan

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Posted 05 June 2020 - 01:02 PM

MOD-3C Trimmer/Pot:

~ 13.8mm body diameter
~ 11.5mm body length

PVS-14 Trimmer/Pot:

~ 12.7mm body diameter
~ 9.5mm body length
 


Sorry, not sure what the DIY is?!

 

Transplanting the tube from a MOD-3 over to a PVS-14 or ???

 

DIY - Do it Yourself. In other words, could without special skills do it at home, and what tools would be be required?

 

 

The PVS 14 pot sounds like it would fit with room to spare. 



#29 11769

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Posted 05 June 2020 - 02:23 PM

The MOD-3 pot mounting is less than ideal to begin with. Essentially an interference with the housing. The pot diameter is about as big as the collar on the pot that provides the press fit. Just don't get your hopes up on being able to fit any bigger pot, like from a PVS-14, in there. With L3 tubes, I've noticed a lesser "felt" difference in adjustment between a PVS-14 and a MOD-3C. The adjustment range is just compressed into a smaller span of the knob. Could replace the 250k Bourns pot that comes with a MOD-3 with a lower value pot and stretch out the gain adjustment range over a greater span of the knob. Alternatively, could also add a fixed parallel resistor to the pot to stretch out the span but the "felt" adjustment range might feel a bit "funny". 

 

The L3 tubes reach max gain well below the max setting of the pot on both a MOD-3 and a PVS-14. Can also be safely operated with no pot or with the pigtail disconnected. Big no-no for earlier/other tubes. The L3 pigtail can also just be unplugged from the tube body. 



#30 cnoct

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Posted 06 June 2020 - 01:05 AM

DIY - Do it Yourself. In other words, could without special skills do it at home, and what tools would be be required?

 

 

The PVS 14 pot sounds like it would fit with room to spare. 

 

Ok, just didn't know what it was you wanted to DIY smile.gif

 

The tolerances are so close that the friction retention washer should be enough, if not just sleeve the smaller diameter pot, even building out with Scotch tape could work. 

 

If you need the potentiometer for the PVS-14 let me know, have OEM spares with knobs. 




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