Hi All,
Well, I purchased an old BFO/TR recently. This is a PNI Varmit from the 70's era that didn't initially work. Fortunately, the problem was nothing more than a dirty switch and with a shot of WD 40, it was up and running.
BTW, if anyone has a schematic of this detector, I would appreciate a copy of it if that is possible.
What surprised me was the fact, this detector appears to work both as a BFO and with the flip of a switch, changes to a TR type detector. Considering it is using a mono type coil commonly found on a BFO, I was surprised that a TR could be built using it. Anyway, it does work and quite well for the old TR type design.
One thing that intrigues me is when in the TR mode, it is less sensitive to ferrous objects and has decent sensitivity to today's coins.
On the down side, this detector suffers from the ground sensitivity associated with both TR and BFO type detectors.
What is interesting is the fact that the tuning capacitor is used for both the BFO and the TR mode
Now, I need to see if I can add a couple of features when time permits that might make it more useable in bad ground.
Once again, if anyone has a schematic of this detector and is willing to share a copy of it, I would appreciate it.
Reg
Well, I purchased an old BFO/TR recently. This is a PNI Varmit from the 70's era that didn't initially work. Fortunately, the problem was nothing more than a dirty switch and with a shot of WD 40, it was up and running.
BTW, if anyone has a schematic of this detector, I would appreciate a copy of it if that is possible.
What surprised me was the fact, this detector appears to work both as a BFO and with the flip of a switch, changes to a TR type detector. Considering it is using a mono type coil commonly found on a BFO, I was surprised that a TR could be built using it. Anyway, it does work and quite well for the old TR type design.
One thing that intrigues me is when in the TR mode, it is less sensitive to ferrous objects and has decent sensitivity to today's coins.
On the down side, this detector suffers from the ground sensitivity associated with both TR and BFO type detectors.
What is interesting is the fact that the tuning capacitor is used for both the BFO and the TR mode
Now, I need to see if I can add a couple of features when time permits that might make it more useable in bad ground.
Once again, if anyone has a schematic of this detector and is willing to share a copy of it, I would appreciate it.
Reg