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Richard and John,
Thank you for the information you provided.
I have a set of Tannoy monitor gold 15" speakers that have a lesser
magnetic field than my oven, and the last thing I would do is to place my
master tape on the speaker cabinet. So I wanted to double check that it was
safe to bake the tape in my new oven. I wanted to avoid telling this new
client that his precious master tape was partially erased. I can now go
ahead and bring this tape back to life.
Louis


2013/10/29 Richard L. Hess <[log in to unmask]>

> Louis,
>
> I measured about 1 G very close to the motor in my American Harvest
> dehydrator and about 400 mG where I usually bake tapes (near the top of the
> stack).
>
> No one has ever complained about the American Harvest FD60 erasing tapes.
> Mine is the model with the motor on the bottom, the newer ones have a motor
> in the lid.
>
> To put this in perspective, my tape demagnetizer read 2 G at about one
> foot. 2 G is the limit of resolution of my tri-axis magnetic field meter
> which was in ELF mode and all three axes were measured.
>
> On the other hand, my studio was reading around 1 mG, more when I moved
> rapidly (because I was cutting the 0.5 G earth's field).
>
> The canonical paper on this (maybe the only paper) is Jay McKnights at:
> http://home.comcast.net/~**mrltapes/field-strength-for-**
> partial-erasure.pdf<http://home.comcast.net/~mrltapes/field-strength-for-partial-erasure.pdf>
>
> This might be useful for converting among the differing field units:
> http://www-d0.fnal.gov/**hardware/cal/lvps_info/**engineering/mag_conv.htm<http://www-d0.fnal.gov/hardware/cal/lvps_info/engineering/mag_conv.htm>
>
> Cheers,
>
> Richard
>
>
>
> On 2013-10-29 12:51 PM, Louis Hone wrote:
>
>> It's been a while since I've baked tapes in the oven. I'm about to embark
>> on a project that involves baking half a dozen Ampex 456 quarter inch tape
>> on 10.5 inch reels. We have a new kitchen oven that has a dehydrate
>> setting
>> (130 degrees F) so it seems perfect for the job. However, I notice that my
>> Trifield Meter indicates that the magnetic field is way over 100
>> milliGauss. My old oven in which I baked many tapes, probably had the same
>> reading but I never measured it. I'm not too thrilled subjecting a master
>> tape to such a strong field. Has anyone else ever measured the magnetic
>> field of their kitchen or tape baking oven/dehydrator ?
>>
>> Louis Hone
>>
>>  -- Richard L. Hess                   email: [log in to unmask], Ontario, Canada                             647 479 2800
> http://www.richardhess.com/**tape/contact.htm<http://www.richardhess.com/tape/contact.htm>Quality tape transfers -- even from hard-to-play tapes.
>