Tweet
Can a F75 wiring configuration at the connector be changed to work on the T2 or the F19?
-
-
Originally posted by markg View Post
Are the connectors different ? a quick look at Kellyco shows both the 75 and t2 have multiple coils and are both 13kHZ -
No, the F75 coils are just for the F75 (and F70, and F75 LTD )Comment
-
Here is Dave J quote:
"The T2 transmitter circuit is designed specifically for driving a DD, and it'd be very difficult to make a concentric to run on it. Don't expect it to ever happen.
The F75 has a completely different transmitter circuit that doesn't care whether a searchcoil is concentric or DD, but in any case the searchcoil has to be wired to work on the F75.
The T2 searchcoil is wired specifically for the T2 transmitter circuit and is completely incompatible with the F75, and vice versa. "Comment
-
Amazing how much information comes from this site.
Can the F75 5" coil be rewired (at the connector) to work on the F19?Comment
-
I scooped this off the Net Some Place years ago. This gives a bit more info.
'''FISHER COILS ???? (- General)
by Dave J., Friday, November 18, 2011, 04:40 (1 day, 6 hours, 58 min. ago) @ BIG SILVER CLARK
Over the last several years we've introduced a lot of new models in several different product lines. At times it has resulted in some confusion as to what's what. Knowing firsthand what dying pains feel like, I prefer the pains that come with growing.
So much for editorializing.
* * * * * * * *
The F2/F4 coil is electrically the same as the legacy BH series. But with a CB mike style connector. Nowadays. Originally it had a BH compatible DIN connector and is still available in that configuration for BH and original F2/F4 machines.
It is not electrically compatible with other Fisher or Teknetics products. It probably won't damage them but will NOT work correctly.
If someone has coils they can't figure out what's what, here's the straight skinny: get an LCR meter that tests at 1 kHz. And probe around the contacts until you find what is obviously the transmitter.
F2 Series: Receive coil (pins 1 and 2) is 2.4 mH , R = 5 Ohms.
Transmit coil (pins 3 and 4) is 2.4 mH in parallel with (220 nF + 22nF), resonant at 6.6 KHz. DC resistance of coil is 8 Ohms.
An alternative TX would be 220nF and 2.65 mH, though I haven't tried it.
Capacitors: the 220 nF would be best if polypropylene, though polyester/mylar would be OK. The 22 nF will be fine in polyester (and could be 20 nF)
Legacy BH series: approx. 2.4 mH.
T2 only: approx. 680 uH, center tapped with some positions reading about 170 uH.
F75/F70: approx. 660 uH.
GB, GB Pro, G2, F5, Platinum, Gold, Gamma, Alpha, Omega, Delta: approx. 880 uH. Concentrics in this series are NOT specified for use on the GB, GB Pro, or G2 although in some instances they may seem to work.
If this information was useful to anyone please let me know by posting here.
--Dave J.
"""Comment
Comment