[Amps] HV lytic max V ratings..some notes.

[Carl]

>
>> I notice the stock  200 uf  @  450 vdc caps  in my 4 x old 1977 era 
>> Drake
>> L4B's  seem too last
>> forever. B+ on em is 2650 vdc  NO load on RX.   2650/3600 = 73.6%    A
>> heath SB-220 and similar
>> amps  with the same  8 x 450 vdc caps, run at 3300-3600 vd.... don't fare
>> as well after yrs of use.
>>
>
>
> ** The Drake secondary is 780/1065 VAC. The Heath is 860/1171 VAC.  Where 
> do
> you get your numbers from?
>
> ##  all 4 of my drake L4PS  are 670/ 940 VAC.    I know several Ameritron 
> owner's,
> whose B+  is  3600-3790 vdc.. depending on their line vac.   I know of a 
> few.. who
> moved to a new home.. and vac was as high as 257 vac.. and caps exploded ! 
> With the
> line vac  up to 247.. a heath sb-220  can easily hit 3550 vdc.    The 
> ameritrons are maxed
> out.. with just 240vac.
>
>
>
>
> ** Most of the SB-220 series I get thru here have good original caps. Get
> rid of the 30K heaters and go with 100K MOX and verify that the voltage
> deltas arent excessive. I use the standard Mouser 5% Xicon, no need for 
> 1%.
>
> ##  I have had  5% tol.. that were  4% low... then the next batch are  3.9 
> % high.
> IF you have caps that are almost maxed out  [due to excessive line V]..
> it works out nicely to  at least have better matched eq resistor's.


** That certainly wont happen with the SB-220.


>
> ##  The deluxe  1%  tol resistors... [ that are actually .1%]  were 
> relatively
> inexpensive.   It was getting tedious.. trying to matchup 24-30 
> resistors..
> then  repeat 8 x more times.
> I can afford the extra 2 bucks  buying a box of 1% resistors... since I
> didn't drop  $10K on an Emtron.    lol
>
>
>
>
> ** Amazingly Im still getting mid 60's NCL-2000's in with original caps.
> National used a custom built 80uF  450V rated for high ripple current, 
> about
> an inch longer than a comparable Sprague Atom.
>
> ##  OK.. how do they work with real caps in em... like 560 uf variety ? 
> ..or
> bigger.   The screen HV cap in the NCL-2000 wasn't too big either.  Think
> the NCL-2000 uses  6 caps for the Hv ??    That's  only 80/6 = 13.34 uf...
> that's  like  6%  ripple.

They use 8 and ripple has never been noticed on the air. That was a lot of 
uF in 1962-63. I used 330uF  CDE 381LX Snap Ins on the rebuild of my 6M 
version and had to use perf board since they are too fat for chassis and 
cabinet clearance using the original phenolic assembly. The locals didnt 
hear any difference.

Carl
KM1H



>
> later... Jim   VE7RF
>
>
>
>
> Carl
> KM1H
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