Ok so I have never done an RF amp from scratch only repaired them and modified them. I know from past experince that 10m band often by the time all the math was done I needed something like 4-8pf but seldom could I find an air variable in that low of a range that would also fit the case. So you almost always sacrificed the best Q for what would fit the case.
So know that I am looking at building my own amp from scratch and am looking at some of the air variables on the market they all seem huge?!?! A lot of these are rated up to 4500V and and are in the 32-800pf range. So why on earth would anyone need that large of a pf range on the air variable???
From practical experience what range do you guys find to be the most likely to be used and the easiest to tune? I am trying to find reasonably priced multi gang set up's over these massive giant single gange beast's???
I have never had to repair or replace any of the parts in a multi-band HF amp's input tuning stage before so I have no clue. Considering the fact that coupling caps are used to join sections in the circuit I can not imagine one needs 240pf on either the tun or load side but that is just me making an assumption.
So some input would be welcome. Experience trumps most book knowledge any day of the week in my book!
So know that I am looking at building my own amp from scratch and am looking at some of the air variables on the market they all seem huge?!?! A lot of these are rated up to 4500V and and are in the 32-800pf range. So why on earth would anyone need that large of a pf range on the air variable???
From practical experience what range do you guys find to be the most likely to be used and the easiest to tune? I am trying to find reasonably priced multi gang set up's over these massive giant single gange beast's???
I have never had to repair or replace any of the parts in a multi-band HF amp's input tuning stage before so I have no clue. Considering the fact that coupling caps are used to join sections in the circuit I can not imagine one needs 240pf on either the tun or load side but that is just me making an assumption.
So some input would be welcome. Experience trumps most book knowledge any day of the week in my book!