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Re: [Amps] Microwave Oven Autopsy

To: amps@contesting.com
Subject: Re: [Amps] Microwave Oven Autopsy
From: Tony King - W4ZT <amps080605@w4zt.com>
Date: Fri, 17 Mar 2006 02:13:03 -0500
List-post: <mailto:amps@contesting.com>
My experience with the MOT is that it does not deliver a constant 
voltage. In fact, quite the opposite.  There is quite a bit of voltage 
drop with load in the supply I built.

I agree with the earlier comments regarding FWCT vs FWB with two 
transformers. You can get more current out of two with a FWB and the 
secondaries in parallel but, with MOTs, you must be sure that they are 
identical so you have the same voltage from each. It's still possible to 
use a pair that aren't exactly the same by using TWO full wave bridges 
with one filter capacitor bank but that's a lot of trouble to go through.

While I might consider using one or two MOTs for a fun little amp with a 
single GI-7B in a real little box, I doubt I would use them for anything 
serious unless I had no other option.  They still run hot with no load, 
even with the magnetic shunts removed and that's not fun. That is unless 
you key the high voltage on each time you transmit. Not exactly the most 
desirable thing to do but it WOULD work if you were pinched for parts 
and watts.

73, Tony W4ZT

KD7QAE wrote:
> correct.
> 
> Bill Turner wrote:
> 
>> ORIGINAL MESSAGE:
>>
>> At 07:07 PM 3/15/2006, KD7QAE wrote:
>>
>>  
>>
>>> Ferroresonant transformers
>>> will run quite hot as the core losses are 2 to 4x per pound those of
>>> high quality linear transformers but they do the one thing that no
>>> linear transformer can do, deliver a constant voltage with no active
>>> devices.
>>>    
>>>
>> *********** REPLY SEPARATOR ***********
>>
>> If I remember correctly, they also do a crude form of current 
>> limiting too, don't they? In case of a short circuit or an overload 
>> they won't try to dump the entire output of Hoover Dam into your cooking 
>> space.
>>
>> 73, Bill W6WRT
>>
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>>  
>>
> 
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