Transient Voltage Supressor

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Transient Voltage Supressor

Postby K9ACT » Mon Aug 23, 2010 11:44 pm

When ordering the 1.5KE18CA from Mouser, I was told that it comes in two flavors, 15V and 18V. I hadn't a clue so I ordered a few of each. What I received were two identical parts with the same marking and ID but the bag they came in said one was 18V and the other 15V. I forget which but only one said "bi-direction" on the bag but they were different manufacturers so it could just have been left off the label.

They look exactly like the one I got from Steve and aside from trade marks, have exactly the same ID.

I can't seem to find a data sheet for a CA and the A version is the same voltage (18) as the non a.

Can anyone help me out on this? and while at it, just what is the purpose of this device?

And is it safe to assume that it is non polarized and can go in either way?

Thanks,

Jack
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Re: Transient Voltage Supressor

Postby Gilly » Tue Aug 24, 2010 4:52 am

Hi Jack

Good to here that your AM System is going well....

This is a copy and paste from Steves WEB Site:

The 1.5KE18CA TVS works very well in protecting the gates. This is a 1500 watt, 18 volt device. The device starts to clamp at around 19.5 volts, and effectively keeps the gate voltage at or below that point. The TVS is is used to clamp accidental high gate voltage. It is not designed to be clipping the gate waveform under normal, steady-state operation, and excessive TVS device heating and device failure may result if the gates are overdriven for too long.

And is it safe to assume that it is non polarized and can go in either way?

Yes that right...

I don't actually use them but if you only had the 15Volt ones they should be fine to use....


Wayne
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Re: Transient Voltage Supressor

Postby kf1z » Tue Aug 24, 2010 8:00 am

18 volt devices come in either 15 or 18 volt operating voltage.

I would choose the higher operating voltage myself.

However when you look through the ordering page, there are many choices.
One thing to be mindfull of is some of the packages have HUGE capacitances...
Some over 4300pf .
This can be an issue depending where it's used.

Same with the 1.5ke540A for the amplifier.
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Re: Transient Voltage Supressor

Postby K9ACT » Tue Aug 24, 2010 8:58 am

kf1z wrote:18 volt devices come in either 15 or 18 volt operating voltage.

I would choose the higher operating voltage myself.


Same with the 1.5ke540A for the amplifier.


Sounds like I should be using one in the RF deck?

Does this also apply to Class D RF? If so, where does it go?

js
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Re: Transient Voltage Supressor

Postby kf1z » Tue Aug 24, 2010 10:22 am

In Steve's design, the TVS diodes are in the RF deck.

18 volt for the mosfet gates (bi directional)
130 for the modulated HV DV input to transformers. (uni-directional)
And 540 volt for the mosfet drains. (unidirectional)

It would be wise for these to be installed in any transmitter Class-D , Class-E ...
Simple mosfet/driver protection against SHORT duration pulses.


See steves 450 watt class-E for placement
http://classeradio.com/8_fet.htm
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