[Amps] SB-220 Output Network

Thu Aug 12 18:44:19 EDT 2021

http://www.n3xkb.com/henryinfo/

If it's NOT  there, somebody please send it to me so I can get it there.
I'm always on the lookout for missing information or new to fill in the
gaps after NE7X let the site disappear from the interwebs a few years
back.   I take no credit for anything but scraping what I could from
archive.org and putting it back where people can get to it.

-Bob (N3XKB)

On Thu, Aug 12, 2021 at 4:29 PM Joe <nss at mwt.net> wrote:

> The amp has been working perfectly fine for 2 years now not a single arc
> ever.
>
> I will try to find the spec's for the 3K unless someone knows where some
> is.
>
> Joe WB9SBD
>
> On 8/12/2021 5:21 PM, Richard Solomon wrote:
> > With the increase in Plate Voltage you will need a bigger (spacing) Tune
> > Cap also.
> >
> > 73, Dick, W1KSZ
> >
> > On Thu, Aug 12, 2021, 3:15 PM Mark Bitterlich <
> markbitterlich at embarqmail.com>
> > wrote:
> >
> >> You might consider looking at the network design values of the Henry 3k
> >> that used a pair of 3-500's. Both the 3k and 3k-A ran those tubes with
> >> about the same plate voltage you mention. They could exceed 2K key down
> >> output with a lot of drive, but were also were probably into distortion.
> >> It's just a thought, but why reinvent the wheel?
> >> -------- Original message --------From: Joe <nss at mwt.net> Date: 8/12/21
> >> 1:42 PM  (GMT-05:00) To: Nidhog <robrk at nidhog.net> Cc: Amps group <
> >> amps at contesting.com> Subject: Re: [Amps] SB-220 Output Network
> >> Thanks,Will check it out.It's all working and has worked perfectly
> without
> >> any issues of any kind for over 2 years now. No arc's nothing at all.
> it is
> >> just to make it have a well you know the load cap is in a good spot you
> >> have to run 1400+ watts.And want to finally be able not to have to.Joe
> >> WB9SBDOn 8/12/2021 12:28 PM, Nidhog wrote:> You are trying to put a 427
> in
> >> a Vega.> Go read a handbook or go here.> I don’t have a Microslop
> computer
> >> to do the software.> Mouse down and do his Pi net design.> Bet there’s
> >> others, on the net.> http://www.ifwtech.co.uk/g3sek/ <
> >> http://www.ifwtech.co.uk/g3sek/>>>> Sent from my iPad>>> On Aug 12,
> 2021,
> >> at 12:57, Joe <nss at mwt.net> wrote:>>>> Hopefully some of you here may
> >> remember my adventures with this SB-220.>>>> I'm the one that ran RTTY
> at
> >> full power in a RTTY Contest and >> literally melted down the HV
> >> transformer.>> And in the process toasted a LOT of other stuff with
> it.>>>>
> >> So a complete re-build and change of the HV section was needed.>>>> So
> >> after looking at what a Pair of 3-500Z's can actually do, I >> decided
> to
> >> try to get all I can from them.>> Think like a Big Henry Amp.>>>> I
> looked
> >> at the Eimac data sheets. And found a suitable HV transformer.>>>> This
> amp
> >> now has 3800 volts at rest on the plates and at full load >> 3600 to
> 3700
> >> volts.>>>> Problem is, running this much higher voltage has changed the
> >> values >> of the output network components needed to be to obtain a
> match
> >> now.>>>> It was discovered that on EVERY Band, until the amp is making
> 1400
> >>>> watts or MORE the load control wants to be fully meshed, max amount >>
> >> of "C" available.>>>> Once it gets above 1400 watts, then you can get a
> >> peak on output >> power when adjusting it.>> But it is still a very
> small
> >> less "C" like 5% less than maxed out.>>>> So a simple thought was add
> more
> >> "C" so added a nice variable in >> parallel with the load cap.>> This
> cap
> >> was about 1/2 the value of the main load cap, so thought >> this should
> be
> >> plenty.>>>> I was amazed to see that if it made any change at all, it
> was
> >> very >> minimal.>>>> So with discussions with many on this group and
> >> elsewhere, it was >> decided that because of the higher voltage, this
> amp
> >> needs more "L".>>>> That is a major re-do for sure so I set that on the
> >> side. So >> continued to use the amp at 1400 watts or more.>>>> Thats
> been
> >> geez 2 years now? The AMP is still running great! But >> often I did not
> >> need or want to run 1400+ watts, So I bit the bullet >> and decided to
> try
> >> to add the More "L">>>> Now I "CAN" just do a poke and not do anything
> >> Scientifically.>>>> Like on the 10/15 coil, just move the 10 meter tap 1
> >> turn longer.>> looking at the 80/40/20, coil, It actually looks like I
> can
> >> add in >> the coil form up to 7 or 8 more turns! The grooves in the form
> >> are there.>>>> Give like 15 meters one more turn,>>>> 20 meters 1
> turn>> 40
> >> 2 turns>> 80 3 turns>>>> And just see what happens?>>>> Or is anyone
> here
> >> great with all that math stuff that I probably >> learned when I took my
> >> extra exam in 1980 or so, but have long forgot >> how to do this kind of
> >> work to calculate the needed components.>>>> But thinking Ok here is a
> >> stock SB-220  a pair of 3-500Z's>> Stock voltage is what? 2500 & 3000
> >> volts>>>> With stock caps and the pair of 3-500Z's How much "L" is
> needed
> >> on >> each band.>> I would assume that is how much "L" was designed in
> the
> >> Kit.>>>> Now raise the voltage to 3600 to 3800 volts.>>>> Now how much
> "L"
> >> is needed with the rest still stock?>> for each band?>>>> and using the
> >> stock 1.75" coil form, how many turns should be the >> best chance of
> >> working for each band segment?>>>> Anyone willing to try a gander at
> >> this?>>>> Joe WB9SBD>>>>
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