[AMRadio] AM amp from 807's ? (+Rons HV Supply/Round Table)

[Bruce - KB6LWN]

Page down for the 807 question.

On Thu, 17 Jan 2002 w5sum at glowbugs.com wrote:

> I finished the HV supply for the 805's last night, works very very 
> well.

That's GREAT news Ron...
It's nice to hear about projects coming to completion
(have many here that need to move in that direction :)
and that they operate as designed.  Way ta Go!

Say...  I think I heard your call on 80m last night.
Were you chatting with a bunch of fellas in a round
table at about 3 or 4 AM ?  I was just getting ready
to shut down for the night and decided to turn up the
AF gain on the HQ-110.  Heard this group fairly well,
except for the SB'ers that seemed to be trying to do
their best to interfere - even heard what sounded like
bursts of RTTY while one fellow was commenting on how
warm (underwear weather) it was on his back porch.
Not sure of the freq, as I still need to do some align on
the 110 when/if the VTVM i have ordered ever gets here.
Dial says it was 3920, but I'm not sure it wasn't as far
down as 3860...  :-(

Just read your posts AGAIN!  <---------------
Yup...  Must have been you I heard.. ;)
I thought the call sounded familiar.
Grid here is CM88 (Lake County CA) and had a 45 copy
on you using the HQ-110C and a makeshift dipole cut
for 6m - hung from the ceiling above the radio fed
with TV twinlead :)

   -=-   -=-   -=-

On to the question at hand...

I have several 807's and 1625's here that I've obtained
from various places over the last couple years, and I just
recently acquired an HT-40 that should be here within the month.
The HT-40 caught my eye because it covers the 6m band as well.

Since the AM output of the Halli' is only going to be
about 20-25 watts (and I prefer to op a little on the
low side of maximum), I'm wondering if anyone might have
a schematic of a proven design for using two 807's in
push-pull, or perhaps two push-pull pairs in parallel
that could be comfortably driven by the HT-40 ?

===
Schematics and construction pics gladly accepted via
direct eMail (NOT attached to the list please), and
I'm limited in display resolution so not much more
than about 800x600 would be best.  URL's to diags
online work also...
===

I realize the maxfreq of the 807 is 60 Mc, but perhaps
with some good layout planning and some finnageling of
lead/component dressing, and maybe some extensive tube
and stage shielding and cooling (ala tin can chimneys)
it can be op'd on 50.4 Mc without too many parasitics.
Plus, I've read that if the plate/screen potentials are
reduced to 90-95% of max, the max operating freq goes
up just a little bit.

So...  Basically, I figure we're looking at tuned input
and output circuits, the proper matching of these stages
to the set (2 or 4) of 807's (or 1625's), some filter
stages to clean things up a bit, and a PS (700vdc plate,
300 vdc screen, both variable), and some metering, for
an amp that I should be able to sit beside the HT-40
on the desktop, and would provide somewhere in the area
of a fairly clean 200-300 watts.  Anyone concurr ?

> 57 degrees this morning in Shreveport Fellows. The 3880
> crowd is on now (4:50 AM) so I gotta go

Like I said...  Must have missed the above 1st time thru.
Sorry :(

> 73's and god bless

Right back at ya bro...  With a Big "G" :)

Bruce