Fisher F-Pulse / Teknetics Tek-Point Pointer Performance

[GoldenKiwi]

Frequency increases with offset. Theoretically a higher frequency will help but this is such a slight change I doubt you will notice any difference.

In the last firmware the Sensitivity setting changes the TX pulse width & pulse delay:

Sens=1 Width=30us Delay=12us
Sens=2 Width=50us Delay=12us
Sens=3 Width=60us Delay=9us

In earlier versions this might have been different.

Hi Carl, sincerely many thanks for sharing! This gives a better understanding thanks!
Ill set mine to higher frequency if possible, even if unnoticeable depth difference! It would now just feel right to!

Thankyou

[Detectorist#1]

Hi GoldenKiwi,

OK. If you haven't interest for grain size targets, your task is very easy. Almost all pinpointers on the stores have possibility to find small coins at 2-3" distance.

[GoldenKiwi]

Hi All, I tested my April 2019 purchased Tek-Point, a current manufactured (I checked the specific Serial Number with FTP) F-Pulse, and my new TRX with a few small gold nuggets. A few notes and observations;

• Tested inside my residential house doing air tests only. Nothing fancy.
• The pointer was held static, and the target attached to a wooden ice-cream stick with Blu-Tak and waved in front of the detector. Hence I assume no Earth Field consideration.
• TRX was set to Sensitivity 4 (highest), and was a bit twitchy - perhaps too twitchy inside my house but I managed to get repeatable tests. Sen3 would have been more usable. The detection distance was generally consistent and repeatable.
• Tek-Point and F-Pulse both set to High Sensitivity, with Led, Beep and Buzzer enabled. I then tested both at two frequency offsets.
• My Tek-Point seemed stable enough to be tested at both ends of the offset range. My F-Pulse was too twitchy at the two highest offsets, I used it in the 3rd highest. I assume that the offset frequencies that gave best results were the highest PPS, although I didn't scope it.
• Both Tek-Point and F-Pulse detection distance varied a fair bit. I found the minimum distance excellent and fairly repeatable, however as I continued to test I found that I would achieve some exceptional (+25% or similar) and subsequently repeatable tests with subsequent sweeps back and forth of the target. I don't know if this is expected or could be explained, or just random effects of multiple tests.
• Interestingly I could generally not detect a 0.092g gold target (did once or twice up to 3mm) with either Tek-Point or F-Pulse, but could easily detect a 0.063g target (sub 1 grain). I didn't have any smaller gold pieces.
• The gold pieces are fairly typical flattened oval-ish flake shapes with exception of the 0.363g piece which is flattened but longer and thinner rectangle shape (maybe why less range with the TRX on this piece) I might repeat with piece around 0.5g, 0.2g and under 0.05g to explore the lower end.
• While the numbers I have uploaded suggest some differences between the Tek-Point and F-Pulse, I felt they were roughly the same. I also tested the F-Pulse in 14/16 offset position (marginally lower PPS?).

[Detectorist#1]

Hi GoldenKiwi,
All these experiments are interesting but in the practice is more important final utility of the efforts. If the efforts and the lost time are not pay outed - what's the point?

[Detectorist#1]

I loosed two years for design pin-pointer capable to find surely 1 grain gold target at 1" distance only to understand that in the practice this is not very useful.

[ivconic]

There shouldn't be any difference between Tek-Point and F-Pulse.
Basically it's one and the same machine.
Maybe the difference is due to different firmware.
Carl is the only one competent to state the correct facts here.
...
BTW I've had F-pulse for a couple of years and I'm very happy with it.
There's no way I'll ever replace it with another one.

[GoldenKiwi]

Hi GoldenKiwi,
All these experiments are interesting but in the practice is more important final utility of the efforts. If the efforts and the lost time are not pay outed - what's the point?

Hi Detectorist#1, Im pleased you found the experiments interesting. You ask "what's the point?".

As per Post#1, I have found an early 2019 Tek-Point to be excellent for my use case (gold nuggets around 0.1g and up) and wanted to understand if the performance of the latest manufactured ones have any difference in performance and if I could expect better or worse performance for a new one. I wanted to know if I was missing out on anything with an older unit. Carl suggested there shouldn't be any real difference in performance, just the human interface. I decided to buy a new one and try it first hand, and whilst the results between my two units differ, they are practically about the same. I never expected any difference between a F-Pulse and Tek-Point, as far as I knew/know, they are the same, and just differ in colour and branding.

I also wanted to compare with a TRX as they are almost of mythical status!

The time expended was quick, it was useful to me and I hope interesting to others.

[GoldenKiwi]

I loosed two years for design pin-pointer capable to find surely 1 grain gold target at 1" distance only to understand that in the practice this is not very useful.

I personally find the F-Pulse/Tek-Point useful in this context, and 1" would be amazing, but unsure if its worth 2 years so I understand your comment thanks!
I'm very impressed with the F-Pulse/Tek-Point hence my interest if any more performance could be expected from a new one, and the thread.

[Carl-NC]

All: The TekPoint and the F-Pulse have absolutely identical circuits & firmware.

GoldenKiwi: The damping resistor is R33. Per your photo it is unpopulated, which I did not recall but checked the schematic and that is correct. This means the preamp input resistors (R1,R2,R3) provide all the damping. The 10Ω resistors limit the H-bridge current in the coil. The overall battery current in idle state (no response) is about 50mA. You might try reducing the 10Ω to, say, 5Ω to increase the TX current but my recollection is it doesn't buy much, and increases power consumption.

[GoldenKiwi]

All: The TekPoint and the F-Pulse have absolutely identical circuits & firmware.

GoldenKiwi: The damping resistor is R33. Per your photo it is unpopulated, which I did not recall but checked the schematic and that is correct. This means the preamp input resistors (R1,R2,R3) provide all the damping. The 10Ω resistors limit the H-bridge current in the coil. The overall battery current in idle state (no response) is about 50mA. You might try reducing the 10Ω to, say, 5Ω to increase the TX current but my recollection is it doesn't buy much, and increases power consumption.

Amazing thanks Carl, VERY much appreciated! Yes, I plan to have a look at the damping and try a few ideas to do some learning . THANK YOU