Have an 8500b. Need to install a new coil. It has the original coil. However the shell is cracked. Just got it and will see if perhaps CA will fix it and seal it. My question is what other coils will work. I was told some Whites will with an adaptor, some BH coils. Curious if a blue maxx would work
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Teknetics 8500b
- Thread starter N9IXW
- Start date
MarkCZ
Well-known member
The whites coils that work are from the much earlier models, likeN9IXW said:
The 5000/D
The 6000/DI
and you would also have to either have an adapter that 8500 originally came with the adapter.
There was some earlier bounty hunter coils that would as a direct fit and even had the same twist-loc connector, if you see any bounty coil with that connector I'm pretty sure it will work.
Next is the earlier bounty coils that have the push in plug connector will also work and its my understanding that the inside plug in part of the twist-loc is actually the same as the bounty hunter push in plug, meaning that the push in bounty plug with plug right into the Tek connector, it just won't loc.
Mark
TYVM I had bought this machine on ebay. Seller sold it as parts not working. He knew nothing about how to test it. I assembled it put batteries in it and WOW! It works great. Got the CA glue out and sealed the coil. All functions work as should. Going out in the morning to get batteries for it and then to learn my new machine.
The sweep 3-4 times then look on meter took a bit of getting used too. This was done on a test bench to see how it reacts, as well as to learn a few things about it before going out.
I have a question though. I am going to be getting Nickel Hydrite batteries for it. I need a plug in charger. If I have the specs for the charger I can find one tht will work. Guess if nothing else I will be calling Keith again. Thanks guys and will post pics of first finds with this machine...
The sweep 3-4 times then look on meter took a bit of getting used too. This was done on a test bench to see how it reacts, as well as to learn a few things about it before going out.
I have a question though. I am going to be getting Nickel Hydrite batteries for it. I need a plug in charger. If I have the specs for the charger I can find one tht will work. Guess if nothing else I will be calling Keith again. Thanks guys and will post pics of first finds with this machine...
Ed in SoDak
Member
I have the text version of the 8500b manual here if you need one: http://www.whiteriverprep.com/vintage/tek/tek8500.html
The required battery charger depends more on which cells you installed and whether they are fast or normal charge. Normal charge is usually 1/10th of the capacity. 2000 mah cells would do well charged with 200 ma for 10 to 12 hours. The slower rate heats them less, which leads to longer life.
If the 8500b has built in charging ability and only needs a wallwart to work, it's probably done at the 1/10th rate for the ni-cads that were available at that time, which was probably on the order of 600 to 1000 ma, so the "stock" charging current would be 60 to 100 ma. Doubling that by using a larger wallwart might overheat the internal regulator or associated parts of the charging circuit. So, charging up some 2000 ma cells might take 20 hours or longer in a "stock" configuration.
Some newer cell types are better rated to handle a quick charge, which usually requires some sort of smart charger which knows when to taper off the current. To take advantage of a smart charger, you'd need to remove the pack for charging or provide some sort of custom hookup.
For either fast or slow charge, the voltage of the charger would normally be slightly above the pack's voltage. The pack itself acts as a sort of load regulator. At first, current will be high and voltage low. As the pack charges, it will draw less current and voltage from the wallwart will begin to rise.
Unless you have one or more weak cells. They'll draw a lot of current and keep the wallwart working harder and producing a lower voltage.
It can get a bit dicey recharging a large pack all at once. If one or a couple cells become weaker than the others, they will begin to have more current forced through them and they'll get weaker over time. The total pack voltage will grow less and operate the detector for less time, even though it's only a couple cells that are at fault.
It's a pain to remove them to charge in smaller groups, so just be aware of it and maybe individually test the cells periodically before and after a charge to see if one or more are failing to come back up to a similar voltage as the others.
If the cells are warm from use or being in the hot car, let them cool down before recharging and let them cool after that before using them again. Excess heat boiling off the internal electrolyte is what hurts 'em the most. That and running them down too deeply before recharging.
Batteries are getting better, but the ones that are "affordable" are probably older tech and won't mind a little extra coddling. I'm not sure if the 8500b's built-in charging circuitry could really handle some of the modern high-output cells. The detector may do best with cells that are close to the originals in capacity.
That's not a very difinitive answer, but hopefully these few general guidelines might help.
-Ed
The required battery charger depends more on which cells you installed and whether they are fast or normal charge. Normal charge is usually 1/10th of the capacity. 2000 mah cells would do well charged with 200 ma for 10 to 12 hours. The slower rate heats them less, which leads to longer life.
If the 8500b has built in charging ability and only needs a wallwart to work, it's probably done at the 1/10th rate for the ni-cads that were available at that time, which was probably on the order of 600 to 1000 ma, so the "stock" charging current would be 60 to 100 ma. Doubling that by using a larger wallwart might overheat the internal regulator or associated parts of the charging circuit. So, charging up some 2000 ma cells might take 20 hours or longer in a "stock" configuration.
Some newer cell types are better rated to handle a quick charge, which usually requires some sort of smart charger which knows when to taper off the current. To take advantage of a smart charger, you'd need to remove the pack for charging or provide some sort of custom hookup.
For either fast or slow charge, the voltage of the charger would normally be slightly above the pack's voltage. The pack itself acts as a sort of load regulator. At first, current will be high and voltage low. As the pack charges, it will draw less current and voltage from the wallwart will begin to rise.
Unless you have one or more weak cells. They'll draw a lot of current and keep the wallwart working harder and producing a lower voltage.
It can get a bit dicey recharging a large pack all at once. If one or a couple cells become weaker than the others, they will begin to have more current forced through them and they'll get weaker over time. The total pack voltage will grow less and operate the detector for less time, even though it's only a couple cells that are at fault.
It's a pain to remove them to charge in smaller groups, so just be aware of it and maybe individually test the cells periodically before and after a charge to see if one or more are failing to come back up to a similar voltage as the others.
If the cells are warm from use or being in the hot car, let them cool down before recharging and let them cool after that before using them again. Excess heat boiling off the internal electrolyte is what hurts 'em the most. That and running them down too deeply before recharging.
Batteries are getting better, but the ones that are "affordable" are probably older tech and won't mind a little extra coddling. I'm not sure if the 8500b's built-in charging circuitry could really handle some of the modern high-output cells. The detector may do best with cells that are close to the originals in capacity.
That's not a very difinitive answer, but hopefully these few general guidelines might help.
-Ed
I bought a set of 700mAh ni-cads. What voltage does the charger need to be? AC or DC?
The detector works great. I thought the coil was cracked because of the tape that was on it in the pics. However, that was not the case. The tape is keeping a coil cover in place. Was thoroughly suprised at how well this old machine works. Next on my todo list for it is to see if I can find the Depth mod for it.
My first time out with it was in a yard I had hunted with other detectors. Others had been there with high end detectors. In 30 minutes I had found a quarter on edge, 3 dimes and a handful of pennies. Of the coins I noticed one thing immediately. It differentiates copper penny from zinc clad . Has been raining last couple days... Cant wait to get out while the ground is still damp....
The detector works great. I thought the coil was cracked because of the tape that was on it in the pics. However, that was not the case. The tape is keeping a coil cover in place. Was thoroughly suprised at how well this old machine works. Next on my todo list for it is to see if I can find the Depth mod for it.
My first time out with it was in a yard I had hunted with other detectors. Others had been there with high end detectors. In 30 minutes I had found a quarter on edge, 3 dimes and a handful of pennies. Of the coins I noticed one thing immediately. It differentiates copper penny from zinc clad . Has been raining last couple days... Cant wait to get out while the ground is still damp....
Ed in SoDak
Member
Awhile back, Mark CZ posted a pic of the power supply for older Tek machines. It was labeled 10VAC, 140MA. That one would plug into the Tek and would use the additional circuitry inside the detector itself to rectify the voltage to DC. Start with a 5-hour charge time and see how far it's charged in that time and go from there to find out how long to leave it plugged in.
-Ed
-Ed