[Amps] Transformers for HB?

[Zeitler, Lane LT, FST-1]

Good points Carl. AG6K used to have a nice circuit design on his web
site for an inexpensive yet effective hi-pot tester. Lane Ku7i

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]
On Behalf Of Carl
Sent: Friday, March 26, 2010 6:18 AM
To: Lee Buller; amps at contesting.com
Subject: [Amps] Transformers for HB?

Good points Lee.

Now here Im going to offer a somewaht radical departure from finding a
pole 
pig or 200# WW2 iron.

For the technically savy and safety knowledgeable why not go AC/DC?  Yes
it 
requires caveats and different thinking but KW amps using such have even

been described in QST back in the 50-60's. Voltage multipliers of X8 and

beyond are simple and with todays high value electrolytics filtering and

regulation isnt a problem. With 240VAC input you have about 2700VDC at 
whatever your line and PS fuse can handle. Add 2-4  $10 813's in GG and
you 
have a respectable signal with good IMD. Thats a voltage that a lot of
tubes 
perform well at. The RF components are still easy to find used or if you

want new go to Ameritron.

If the thought of a purely line operated PS still sends shivers down
your 
spine then use an isolation transformer; Ive seen many 1kva and up units

(thats a CCS rating) at hamfests go begging at $50 and less. These
include 
120/120 and 120/240. There are also industrial versions at 5kva and up
that 
will give you various combinations up to 440 and 660V that go begging at

scrap dealers as older buildings are demolished or others get new
tenants. 
All it takes now is some diodes and electrolytics to get some serious 
voltages and power. Insulation ratings you ask?  Thats where the hi pot 
tester comes in, lots of info out there on building one.....cheap of
course. 
I built a 13KV one that isnt pretty but does the job in the shop built 
around a sign transformer. For roaming around I picked up a 5KV
industrial 
one at a local surplus shop for $25 that is light weight and has a
handle. 
Ive found most industrial rated iron to be good for at least 5 KV; maybe

thats why they are premium priced when new. Put it in a plywood box with

warning labels if they worry you.

Get creative and think outside the box. Just dont wind up inside a box!

Carl
KM1H



>
> I love to build, but I opted to operate and contest and stopped for a 
> decade or more.  I got back into building because of Elecraft and the
K2. 
> Nuff said about that.
>
> I find it hard to find parts.  Well, I will be blunt here.  I don't
like 
> to "pay" the price for today's parts.  Now, with that said, let me
explain 
> a little.  I got my first license in 1965 at the age of 15.  Parts
were 
> plentiful still from WWII and ripping apart old TV sets that had
massive 
> transformers.  I still have some of those parts.  They were either
cheap 
> or free.  Free!  Many times, Elmers would give me their junk.  That is
how 
> I build my first amp...a pair of 811As in Push-Pull class B.  Hey, it 
> worked!
>
> Now, you cannot find "free" anymore...or at least it might be very
rare. 
> Again, I need to change my building paradigm to something else....I
cannot 
> be cheap...and it ain't going to be free.
>
> For instance....I have been looking at building a GI-7B amp.  Tubes
are 
> cheap and plentiful  I have many of the parts I need...variable caps, 
> coils, meters, etc.  I can homebrew a tube stock easily.  But, I
cannot 
> find a transformer that isn't going to cost me, what I think is an 
> outrageous price.  Again, I have to change my paradigm.
>
> Finding parts for RF - tubes, caps, coils, chokes - seems to be fairly

> easy to find at a reasonable price, but when it comes to iron
transformers 
> there is not a lot to choose from that doesn't cost you 300 to 500 
> dollars.  I just discovered transformers at MFJ and that seems to be
the 
> best deal out there.
>
> Why build something, when you can buy an amp for 700 dollars?
>
> Also, some people have no skills drilling a hole or using tools.  Shop

> class in High School is long gone.
> A lot of people entering the hobby have opted for homebrewing
software, 
> not hardware.  Why?  They grew up with computers and gaming equipment,
not 
> radios.
>
> The information to build amps or radios is available on the internet.
A 
> wealth of information is out there, but you must be willing to learn
on 
> your own.  Today's hams have seemed to have lost that aspect of 
> radio...learning something to get that higher class license or a sense
of 
> wanting to know how it works.  Ham Radio taught me that I could learn
by 
> myself.  I did not have to have a teacher....just books...parts....and
a 
> little help from an Elmer.  I wanted to learn.  That is not the case 
> today.  Nuff said, to political in nature.
>
> More could be said, but I have bored the reader already
>
> Lee - K0WA
> "Curmudgeon in Kansas"
> "I still think I am 15"
> "I still think I am cool - even though I am 60 now"
>
>
>
>
> Ham Radio Operators:  Kansas QSO Party is August 28-29, 2010.  See 
> www.ksqsoparty.org for details
>
> In our day and age it seems that Common Sense is in short supply.  If
you 
> don't have any Common Sense - get some Common Sense and use it.  If
you 
> can't find any Common Sense, ask for help from somebody who has some 
> Common Sense.  Is Common Sense divine?
>
> Common Sense is the image of the Creator expressing revealed truth in
my 
> mind. -  J. Wolf
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
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