"N_Cook" wrote in message ...

7x 1mm screws with little washers and pads of silicone under the heads,
through holes in a plate with a reaction frame fitted, and screwed to
the DAT drum. 40 seconds of low heat hot air and the circlip pliers as a
lever and the bottom drum came away. Leaving the ball race on the drive
and the drum separating from the outer section of the race. Upper
ferrite former for thre upper coupling coil seems to be glued to the
central lump. Desoldered at the 4 solder joins but not yet tried heating
the ferrite to see if it comes away. Under that is the head mount
screws. The heads are about 80% the size of VHS heads, and certainly
thinner, will have to find a scrapped 8mm set of heads



VHS heads and DAT heads do not perform the exact same physical task.

You need to research this properly, but AFAIK, VHS heads record stripes of
data with blank "guard tracks" in between, so adjacent tracks do not
interfere with each other (being as the system is analogue).

DAT head tracks actually overlap each other, so there is never any piece of
tape with no signal on it.

Meaning the size of the heads in relation to the spacing of the track are
not the same for both formats.


This is important in DATs, because the ATF system, which keeps the head in
the centre of the track, needs to be able to read, via the playback head,
both adjacent tracks' ATF signals simultaneously.
Since tracks overlap, it is able to do this playing back a single track.
If one is lower amplitude than the other, the system will alter tracking to
make them the same, thus ensuring the head is travelling dead centre down
the track.

VHS systems do none of this.



This is all from a 10 year memory, and I haven't bothered to check any of
it, but I believe this is basically the case.
I don't mind being proved wrong.



(I'm not sure whether your above post is considering substituting some other
format head for the DAT head, hence this "heads up" post)



Gareth.