Is the Han-D-Mag a worthwhile investment for servicing your reel-to-reel tape recorder?
The HAN-D-MAG Tape Head Demagnetizer is considered to be the number one demagnetizer used by professionals on reel to reel decks worldwide. This HAN-D-MAG Demagnetizer handheld rugged unit has a powerful sine-wave demagnetizing field over the length of a convenient 2 1/4" reach-anywhere probe. Efficient magnetic design of the HAN-D-MAG has resulted in a 5 times more efficient Head Demagnetizer than any other available product.
HOW RECORDER COMPONENTS BECOME MAGNETIZED
Magnetism is everywhere. It is often found as residual magnetism in iron or steel objects. Magnetic tape recorder components such as heads, steel capstans, and tape guides generally become magnetized through use and sometimes from accidental exposure to external magnetic field sources such as loud speakers, transistor radios, or meter type photometers, all of which contain strong permanent magnets. Heads, normally made of magnetically “soft” material, pick up magnetism readily but are easily demagnetized. Capstans and guides are made of harder steels, which are more difficult to magnetize, but retain such magnetism, making them much harder to demagnetize.
WHY DEMAGNETIZING IS NECESSARY
The magnetic coat on recording tape is very sensitive to extraneous magnetism since the recorded signal itself is only a modulation of the residual magnetism retained in the thin layer of magnetic coating compound. Exposure to subsequent magnetic fields of any consequence degrades the recorded signal. Such degradation is noticeable as a loss or attenuation of the higher recorded frequencies, as well as an increase in unwelcome “hiss” or background noise, which can amount to several dB. Unless offending tape transport components are demagnetized, the condition worsens each time the tape is played. The only way to correct this condition effectively is to measure magnetism levels regularly, and then demagnetize offending components whenever necessary.
HOW TO MEASURE MAGNETISM IN COMPONENTS
The lower (test) edge of the Annis Pocket Magnetometer is placed in contact with the component being tested. If troublesome magnetism is present, the pointer will instantly deflect, showing magnetic polarity and a scale reading proportional to the level of magnetism in the component at that point. The higher the reading, the stronger the magnetic field is. Magnetometer scale readings relate to magnetic field strength, in gauss, at the staff of the instrument, which has been calibrated in a standard, uniform field source traceable to National Bureau of Standards. Use of the Clip-On Probe in recessed components but does reduce the Magnetometer reading as compared to direct contact. Additional details on Magnetometers may be found in our “Pocket Magnetometers” bulletin.
HOW TO DEMAGNETIZE
FIRST: Turn off the recorder. Make sure all tapes are at least 12” away from the energized Demagnetizer.
SECOND: Plus the Han-D-Mag into any convenient 220 V A.C. outlet.
THIRD: Approach the component to be demagnetized with the plastic jacketed probe. It is rarely necessary to actually touch the part. Just bring the probe tip within 1/8” or _”, wave sideways slightly, then withdraw slowly, while still energized, at a rate no faster than 3” to 4” per second; to a distance of at least 12”.
FOURTH: Disconnect the Han-D-Mag from its power source. For maximum demagnetizing efficiency, the Han-D-Mag is rated for practical intermittent duty. It may be left connected to power for six to eight minutes at a time without overheating. If, by accident, one should forget to disconnect this powerful Demagnetizer, an internal calibrated thermal protector will permanently open the circuit, thus eliminating a fire hazard. Such “forgotten” units can be repaired at a modest cost. VU meters, etc. are safe as long as the energized Han-D-Mag is not brought closer than 1” distance to the meter movement. After demagnetizing is completed, you may use your Magnetometer again to check your proficiency.
PLUS HAN-D-MAG Can Also Be Used for Occasional Bulk Erasing of Tapes
The opposite, flush pole end of the Han-D-Mag has a demagnetizing field strength of over 800 oersteds at _” wide, if a regular bulk eraser is not available.
R.B. Annis Instruments produces precision demagnetizing and testing equipment. The Company offers demagnetizers, magnetometers, and hand d-mags. Annis Han-D-Kits lets you test and actually measure your demagnetizing needs and results.
R.B. Annis Instruments, Inc. builds the finest precision demagnetizing and testing equipment available. Annis designs demonstrate a level of sophisticated simplicity that has earned them worldwide renown, and it is an unparalleled understanding of electro/magnetic design fundamentals which allows Annis engineers to build customized solutions for virtually every technical obstacle. The creative spirit of Annis Instruments grew from the talents of its founder, Robert B. Annis. Born in 1907, Annis developed a technical knack during the heyday of radio, and spent his early career honing the skills that would turn hobby into profession. During the war years, he'd already amassed enough professional kudos to catch the eye of military-industrial fabricators, and he quickly gained a reputation as an intricate problem solver.
Every Unit is 100% tested and is guaranteed to perform as described. Quality First - Always.
RB Annis HAN-D-MAG Demagnetizer - Quality First - Always. Made in USA.