Here some interesting information about transformers.
I asked Bob's opinion about transformers and this is what he send me.
Will, K6NDV
-----Original Message-----
From: Bob Marston <k1ta@earthlink.net>
To: Will K6NDV <k6ndv@contesting.com>
To: <amps@contesting.com>
Date: Sunday, October 18, 1998 9:55 PM
Subject: Transformer Selection
>Here are some hints regarding transformer selection
>
>For Secondary Voltage if you want to use a tuned choke filter You will be
>limited to 1 of 2 rectfier configurations Full Wave Bridge or Full Wave
>Center Tapped.
>
>First Choice: Full Wave Bridge the Secondary Voltage must be between 3000
>volts and 3600 Volts The transformer secondary current rating must be 1 amp
>
>Second Choice: Full Wave Center Tapped the Secondary Voltage must be
>between 6000 and 7200 Volts The transformer secondary current rating only
>needs to be 500ma. Note: The secondary MUST HAVE A CENTER TAP
>
>Third Choice: Voltage Doubler the Secondary must be between 1500 volts
>and 1800 volts with a 2 amp rating. Note: This circuit will preclude the
>use of a choke
>
>Some hints when selecting a transformer. These same techniques can be
>applied in the choke selection. The secondary resistance is a factor in
>regulation. The higher the resistance the poorer the regulation. It's
>simple ohms law and Kirchoff's voltage law if you are swinging 1 amp
>between no load and full load conditions the Supply Voltage will drop 1
>Volt for each ohm of secondary resistance. Bring a VOM with you and measure
>the resistance of the secondary.
>
>CAUTION!!!!! You are measuring the resistance of a storage device IT WILL
>CHARGE UP...Even with a VOM that uses a 9 volt battery. the stored charge
>has knocked this author on his ass. It's an experience you'll only do once
>if you have to learn the hard way.
>
>When you first contact the transformer it will look like a dead short. If
>you have an analog meter you will see the needle rise as it charges. The
>secondary resistance will be the value indicated after the charging is
>complete.
>
>It has been some time since I transformer shopped but as I remember a
>secondary of
>100 ohms is an exceptional transformer
>200 ohms is good
>250 ohms ehhh
>300 ohms or more---Look for another transformer
>
>For a transformer in the 6000 to 7200 volt range you can double these
values
>
>Also check the primary to make sure its not burned out
>
>these same techniques can be used with the plate choke
>
>Bob
>
>
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