[ARC5] 800 HZ Power: Theoretical Question

[Taigh Ramey]

Great information Mike. It will certainly help us with the PV-2’s radar project.
Thanks,
Taigh

Sent from my iPad

> On Nov 19, 2017, at 5:35 AM, Michael Hanz <aaf-radio-1 at aafradio.org> wrote:
> 
> Well, according to the Airborne Electrical Maintenance Notes dated September 1945, there did not appear to be any problems caused by magnetostriction effects. The 1" thick document does describe a litany of maintenance problems stemming from issues like improper power factor correction for alternator loads causing heating in the alternator, poor cooling, improper voltage regulator adjustment, vibration affecting operation and life of the carbon pile regulators, use of the wrong grease in bearings, faulty bearing lots, tight brushes, etc.  
> 
> Not a word about magnetostrictive vibration effects or mitigation for same, on either alternator iron nor transformer iron.  Plenty of photos of the results of problems experienced in Navy fleet operations.  It's a pretty interesting book that I need to scan and put on my website.  There are pieces of it posted at http://aafradio.org/docs/800-1.htm and http://aafradio.org/docs/Voltreg.htm to provide a flavor.
> 
> 73,
> Mike  KC4TOS
> 
>> On 11/18/2017 10:30 PM, Scott Johnson wrote:
>> The big problem is still there:  The unit you are powering has presumably
>> has 800 Hz transformers, and they will sing due to the magnetostriction
>> effect in  the cores.
>> I dare say that is why the 800 Hz "experiment" failed, and 400 Hz became the
>> de facto standard for lightweight AC power applications.  
>> BTW, the magnetosrictive vibration eventually displaces the lacquer between
>> the laminations, causing a marked decrease in performance of the
>> transformer.  This was also a problem in the inverters, and lead to fairly
>> short service life.
>> 
>> Scott V. Johnson W7SVJ
>> 5111 E. Sharon Dr.
>> Scottsdale, AZ 85254-3636
>> H (602) 953-5779
>> C (480) 550-2358
>> scottjohnson1 at cox.net
>> scott.johnson at ieee.org
>> 
>> -----Original Message-----
>> From: arc5-bounces at mailman.qth.net [mailto:arc5-bounces at mailman.qth.net] On
>> Behalf Of David Stinson
>> Sent: Friday, November 17, 2017 11:01 AM
>> To: ARC-5 <arc5 at mailman.qth.net>; milsurplus at mailman.qth.net
>> Subject: [ARC5] 800 HZ Power: Theoretical Question
>> 
>> 
>> Theoretical Question:
>> Goal: Simple, *quiet* answer to the 800Hz question.
>> 
>> You begin with an unknown inductance with a link-coupled output. (Like
>> transformers).
>> 
>> Drive the inductance with a powerful Class-C amplifier, sourcing pulses at
>> freq F.
>> 
>> Make the unknown inductance the PA's "tank,"
>> introducing tank capacitance to bring the "tank" into resonance at F,
>> causing the tank to "ring" and provide a sine-wave output.
>> 
>> Rectify the sine-wave output as a DC power source.
>> 
>> 
>> So....
>> Rectify line AC.  Heavy-Current MOSFET pulses the GP or TBW power
>> transformers at 800 Hz.
>> "Tank" capacitor across the transmitter primaries resonates and allows the
>> transformers to "ring."  Ringing transformers output the voltage and away we
>> go.
>> 
>> Will it work?
>> 
>> 73 OM DE Dave AB5S
> 
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