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H & R Transformers




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Fellow Coilers,
To answer some of the questions that people have asked concerning the H & R
Transformers:

Each transformer is rated at 5KV at 300ma. Primary is 110/120 VAC 60HZ.
(note that since two transformers would normally be used, you can wire the
primaries in parallel for 110 or in series for 220 VAC operation) The core
is quite massive, and I believe you could run these at 50Hz, although you
might have to de-rate them a little. Not having access to 50Hz I cannot
vouch for 50Hz operation, but hopefully someone out there with 50Hz will
buy a couple and get back to the rest of us and tell us if they run OK at
european frequencies.

The physical size of each transformer is 6" tall x 7" core length x 6"
wide. They are heavy duty construction with angle brackets for mounting.
The quality of construction is excellent. The primary is located at the
physical top of the core. The primary is about one inch thick and extends
outward for about 6 inches. It is not round, but somewhat oval shaped, like
a racetrack. Connections are made with large quick-connect terminals.

Below the primary there are two magnetic shunts installed between the
primary and the secondary, one on either side. These are in the form of a
block of laminated core material and some form of insulatory material
wrapped around the block. I have not tried to remove the shunts, but it
looks like it would only require some gentle tapping with a rod and hammer
to loosen them. I like the shunts being there, because it does allow you to
use it for a Jacob's ladder, and eliminates the need for extra primary
inductance to limit current.

The secondary occupies the bulk of the transformer. I do not know what the
wire size is, as I have not disassembled one, and do not plan to either. At
the base of the secondary are three quick connect terminals. These appear
to be part of a resonant winding that a supplied AC capacitor can be
connected to. I believe this was used to help regulate the secondary
voltage. You can operate the transformer with or without the AC capacitor
connected. I am not exactly sure whether the AC capacitor and the base
winding are part of a power factor correction scheme or a resonant
regulator scheme. Each person will have to experiment and determine whether
they want to use or ignore this aspect of the transformer.

Someone questioned whether the transformer was rated for continuous duty.
When I originally ordered my unit the H&R people told me that it was a unit
from some sort of copy machine, and that it was continuous duty. This
sucker is built *solid*. It sure as heck looks like it is built for
continuous duty. I have not personally run it for a full year at rated
load, so I will not make any claims beyond repeating what I was told. Now,
I honestly don't know what kind of copy machine would need such a brute
transformer for its high voltage section, as all the copy machines I have
ever torn apart never had anything as humongous as *this* baby inside. In
fact, the transformer weighs more than most of the copiers I have lifted!

As to its usefulness in a Tesla Coil, I am appending the following post
that appeared here on the Tesla list. It was a response to Malcolm Watts'
call for coil info. You will note that Barry Benson's Tesla coil uses two
Transformers that appear to be the same ones that H&R is selling. Maybe
Barry can give us some more intimate details of how well these transformers
work, and if there are any things about them that we should know.

 ----------
Benson_Barry%PAX5-at-mr.nawcad.navy.mil
From: "tesla"-at-poodle.pupman-dot-com-at-PMDF-at-PAXMB1
To: Benson Barry; "Tesla-list-subscribers"-at-poodle.pupman-dot-com-at-PMDF-at-PAXMB1
Subject: Coil Research
Date: Tuesday, February 11, 1997 2:02AM

-snip-
Secondary Height=27"
Diameter=6"
Turns=~630
Wire diameter=#18 gauge (.0421")
Top terminal Type, Size=toroid, 5 high X 20"diameter
Resonant Frequency with terminal=~200khz
Q without terminal (optional)=haven't measured
Q with terminal (optional)=""""""

Primary cap value=.04
Peak primary cap voltage=14kv (2 5kv photocopier transformers in series x 
1.414)
Breaks per sec=14 X 1750 / 60 = 408
Output length to grounded rod=56"

-end snip-

Barry reported a 56" spark length using a 6" diameter by 27" secondary
using 2 5kv photocopier transformers in series. So, obviously the
transformers do a pretty good job in Tesla service. I am hoping that Barry
will see this post and give us any useful details that he can on the merits
of these transformers, and any special details about using them that he may
have learned along the way. Anyone else out there used these transformers?

My purpose in alerting the members of the list to this transformer is to
share with you what I consider a great find. I bought two myself. I figure
if $20 for a 12KV 30ma neon transformer is considered good, and if that is
only 360 watts, then it would take about 8 of these $20 neons to equal the
power you can get with just two of the H&R units. $180 worth of neons
versus $100 worth of H&R transformer. You have to *see* these units to
appreciate how beautiful they are!

Someone asked if the 100 in stock that I mentioned was all they would ever
have. I don't know. But I tell you this: If we coilers bought up their
entire stock over the next week or so, you can be sure they would keep
their eyes out for MORE! These items have probably *not* been their biggest
selling item, because it is not the kind of thing everybody needs or wants.
But it is *exactly* the kind of thing we coilers can use. How many of you
coilers and would-be coilers were unaware that such a transformer existed?
Or if you knew it existed, how many of you were hesitant to buy one or two
because you did't know if it was going to be useful in Tesla service? I
hope that the info I have gathered about this transformer helps many of you
to finally get a decent power source for your  Tesla coil.

Does anyone else out there have info about any other such bargains that we
could all take advantage of?

Fr. Tom McGahee

*** here is the original post, in case you missed it or misplaced it ***

Fellow Coilers,
Yes, 10KV RMS -at- 300ma for less than $100 delivered in the USA.

I have run across a transformer that is just about perfect for Tesla Coil
work, and I want to let you all in on it. 

Herbach and Rademan have 100 of these transformers in stock. They are rated
at 5,000 volts RMS, 300 ma continuous duty. These are *open-frame*
transformers, absolutely NO tar or anything else to give you problems. Mine
came with power factor correction capacitors included.

There are current shunts installed... which is actually a *plus*, because
it means you do not need any reactance added to the primary! If you insist
on removing the shunts, it is very easy to do so, since it is all open
frame construction!

The secondary is entirely isolated from the core!

I bought two of these and wired the  primaries in anti-parallel. This makes
the phase of the two secondaries *opposite*. That allows me to take the
inner wires of each secondary and wire them together so that the two
*outer* wires of the secondaries are oppositely phased. In other words, the
total series output is now 10,000 volts AC RMS (14KV Peak!) at 300 ma. If
desired, the inner wires of the secondaries can be connected to AC ground,
so that the electrical stresses are reduced. But if you want to, you can
also leave them floating. Both ways work.

Buy two for $39.50 each, throw in about $15 for shipping, and you are under
$100 for an almost perfect 10KV RMS 300ma *open frame* NO TAR transformer
for your Tesla coil. 

The really daring among you can figure out other combinations of these
transformers, I am sure.

Part Number TM92XFR2019  5KV 300ma Transformer  $39.50 each

Herbach and Rademan
18 Canal St.
P.O. Box 122
Bristol, PA  19007-0122

Orders 1-800-848-8001
Fax 215-788-9577
Business hours Mon-Fri 8 am - 5pm EST

Ask to be placed on their mailing list!

Hope that this is something useful for all of you. This is not exactly a
pole pig, but two of these will deliver 3,000 VA at continuous duty. Not
bad!

Fr. Tom McGahee






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