No more
> yo-yoing bias either. 5 to 8.75 vdc bias is nothing short of lousy bias
> regulation.
** That's no different than using diodes with no big electrolytic.....same
result...the bias wanders a bit but really hurts nothing.
Carl
## Not quite. 7 x 1N5408's = 5.005 vdc [ ,715vdc with 150 ma flowing
through em on idle]
This will rise by 12% when 1.5A flowing. Then it's 5.60 vdc
## 8.75 / 5 = 1.75..or a 75% increase..which is a bunch. It's probably no
big deal though, the xcvr
is the limiting factor. And yes, stick a big lytic across the string of
diodes..and the resulting dynamic regulation
is superb, it then barely budges. I like the string of diodes approach, since
it's then real easy to change bias
Vdc to anything you want..and do it on the fly. That's good for
experimentation purposes. Like biasing it off
in class C for FM.... or dropping the idle to just 20 ma for CW use.... or
doing some IMD vs idle current
tests. Unless the xcvr is squeaky clean, you would be amazed at how low you
can lower the idle current
on a lot of GG triodes.
## BTW.. I have given up on the EBS experiments. [ electronic bias
switching] I can't get it to work any better
than before. It works semi good on PTT.... but if using VOX SSB... the EBS
saves so little power between
when you stop talking, and when the vox drops out, it's a waste of effort.
It's of no benefit. On CW, EBS is of no
benefit at all. Cranking up the bias V..and reducing the idle current to 10-20
ma works a helluva lot better.
## with some experimenting in the shop, 1A CCS through a 1N5408 is not an
issue. Any more than that, then
the heat builds up..fast. With the 6A10... 2A CCS is max for that diode.
I also tried paralleling both 1N5408's
and also 6A10's..and can always get the current to divide 50-50...or extremely
close to that.
Later... Jim VE7RF
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