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

[Carl]

>
>
>> ##  any 1.5 kw  CCS out amp with 50-60% eff... will require a bare min
>> of 3000-3500 va ccs xfmr.  You can  buy the alpha 3.5 kva CCS xfmr,
>> as used in all their recent amps, including the 91/99/87A..from their
>> site.
>
>
> ** I wasnt talking about those later amps. I stay far away from
> microprocessor crap.
>
> ## The ameritrons will do 1.5 kw out, so will qro/command/
> palstar/Emtron.  they all have 3.5 kva xfmr's in em.

** Youre starting to sound like someone we know, making up specs on the fly 
(-:
Grab a real Dahl catalog and run the math. Example is the Commander 2500 
Heavy Duty replacement is 900V @ 2A ICAS. The AL-1200, etc is 2570V @ 800ma 
ICAS


>
>> I can understand 330-560uF
>> which  still may place a strenuous starting load on stock amps.
>
>> ## install step start....pretty simple.
>
>
> ** More junk to buy, find room for, and eventually blow unless its
> overbuilt. The Harbach stuff is marginal in a SB-220. Amp Supply uses step
> start in most models.
>
> ## The fix for..'not enough room for step start' is to install it 
> outboard.
> I use 2 x standard 8" square x 4"  tall  metal electrical box's. One DPST
> P+B relay with 30A contacts  applies the 240vac.   2nd Relay is a SPST
> P+B  30A  relay.  Resistor is a 20 ohm-100-150W  Arcol, metal finned unit,
> bolted directly to box.  240 is hardwired to input of box. Power cable 
> from anp
> is hardwired to box as well.  One small control cable  comes  from 8' x 8" 
> box
> on floor... up to a tiny mini box on desk.. with 2 x miniature toggles. 
> One toggle
> turns on 1st relay... then wait a few seconds... then hit the 2nd 
> toggle..turns on
> 2nd relay.   IE: manual step start.  Do the reverse sequence when shutting 
> down
> for the night. Then no back emf  from xfmr, etc.
>
> ## this will also step start the fil xfmr at the same time.   Then you can 
> also do cool
> stuff, like drop the resistor back into the circuit.. then toggle from CW 
> to SSB  hi-B+
> position.. then shunt the step start R out.
>
> ## It's either that.. or fry on/off switch's.. and also  cw/ssb  switchs. 
> Without
> the step start, the peak current is an easy 160-190A through the on/off 
> switch..
> albeit for only a split second.
>


** I could also buy a Mini, place it on a custom tube frame and running 
gear, stretch the nose and run a blown hemi.
Thats about as ridiculous as adding a bunch of outboard crap to a good 
working amp.


>>
>
> ** My backup MLA2500 has 330uF Snap In's installed. More than enough, run 
> cold and dont
> have to be outboard in a plywood box. 8873/74/75's have at least 10-15dB
> better IMD than any Class AB rice box, they dont need any more.
>
> ## Then get a Class A  ricebox.  When toggling between Class A.. and AB
> the difference is just un-real..esp when listening off freq.. with a 2nd 
> RX..aprx
> 4' away.  S-9 crud  drops to zero.


** I wouldnt waste my money on a new ricebox. Its simple enough to rebias 
the TS-940 and add more cooling. Or just use the TS-830. Im less concerned 
about HF IMD where Im rarely on SSB except in an already noisy DX pileup. On 
VHF and up I take it pretty serious.



>
> **  Some tubes cant take all that stored energy from your overkill caps
> without something better than a glitch resistor. We dont all run YC-156,
> 3CX3000A7, 3CX6000A7, 4CX10000A, and bigger like your crowd do.
>
> ## better imd, far better bang for the buck, rebuildable in most cases. 
> You
> can buy any of the above tubes for a lot less, than what it cost to 
> re-tube
> a 87-A.


** How does that help the appliance operator that already has an amp?


>
> ** RCA specifies right on the 8122 spec sheet that above 2200V no more 
> than
> 10uF output C be used. Thats what the NCL-2000 used with 8X 80uF. My 6M
> version now runs 41.25uF ( 8X 330uF) with no damage yet. But the glitch
> resistor has gone from the stock 15 Ohms (Yes a glitch resistor in 1963,
> long before Measures and Rauch invented it) to 50 Ohms which doesnt help 
> the
> regulation. Ive retrofitted a few customer NCL's  with 8X 220uF and 25 Ohm
> glitch.
>
> ## what's the problem with the 8122's and small tetrodes ?   Is it arcing 
> from
> anode to screen ??    What else can the anode arc to ??   How come the 
> guys
> with the big terodes never have a problem, if the anode arcs to the screen 
> ?
> They never damage the screen supply either.


** I suppose thats the reason. Eimac doesnt discuss the subject with their 
small tetrodes. The bigger tubes have a lower Es to Ep ratio as well as 
greater spacing.


>
> ## I use 50 ohm, heavy duty glitch R  on everything.  I also precede it 
> with a fast,
> hv fuse too.  Plus a 2nd HV fuse  between sec of plate xfmr.. and FWB. 
> And also
> a fast mag hydraulic breaker in the 240 line. ..'instant trip'.
> IF  B+  arcs to anything... HV fuse opens up <2 msecs.
>
> later... Jim  VE7RF



** My HB linear and Class C AM amps do similar except for the breaker but Im 
not running your levels of power, or energy storage, on any mode or band.

Carl
KM1H