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Old-time 'conventional' TR's are interesting. eye rolling smiley

September 28, 2018 07:02AM avatar
I've been working on some write-ups regarding TR models and then TR-Disc. units. They can be fun to use, if you understand them and the challenges of using them, and also if they were/are a quality-made product. During the 1960's and '70s, when the recreational use of metal detectors was in its infancy and rapidly growing, there were many, many, many sources selling metal detecting kits or production units, and many of them were rather inferior.

Let me respond to your post and try to offer some help:

I know so little about this. I wasn't even sure if it would be applicable to the previous TR thread.
Yes, it is very applicable to the earlier thread I posed that referred to TR and TR-Disc. detectors. The TR's were a simpler electronic design compared with models that have followed, and Ray Jefferson was one of so many detector makers at the time.

The article you posted said it was priced at $119.95 in the Fall Big Book in 1975, so this suggests your unit might date to 1976. The basic 'TR' models started in the latter '60s and were most popular to about '74, but by then we also had a few years of 'improved' TR-Discriminating models, and in '75 we had our early VLF Ground Cancelling All Metal detectors that soon progressed to two-mode models with VLF/TR-Disc. search mode options.

There were some better quality, major manufacturers who still offered good TR-Disc. models, and even some still carried BFO's, but most major brands were in a fast-paced mode to design the newer technology and better performing detectors and conventional TR's were quickly being phased out and were just about gone in the next ten years.

By 1985 we saw fewer and fewer small scale detector sources being advertised and they simply closed up and faded away. Many of them only made BFO, TR's and some TR-Disc. detectors at budget prices and couldn't compete with the more improved and better featured detectors that major detector manufacturers were offering.

So I was given an old Ray Jefferson detector about a year ago. I dug it out this evening and toyed around with it a little. I opened it and it was cool to see an old open fin type variable capacitor on the "tuning" knob. The "sensitivity" knob looks to be a standard closed type pot.
Yes, old-time components are fun to see, and they are much larger than the parts in our modern devices, to be sure. Some of those older models had to use large and high voltage batteries because they had tubes in them that had to be powered-up. That was before the move to 'transistor' based models.

It does power up, and seems to detect, but in a weird way. Would this thing have been designed to null out on good targets?
No, not if tuned properly. By design, these old TR's fell into two categories. Those designed as a 'Metal' locator or detector that were designed to find non-ferrous metals such as coins, rings and other similar items. The other and primary design first used were called 'Metal / Mineral Locators' or Detectors.

With both types you had a 'Null' adjustment zone where they were silent. In order to Tune them for peak performance, you would adjust the 'Tuner' control from the silent 'Null' zone towards the 'Metal' side and keep the search coil at a proper operating height of about 1" or 2" off the ground surface.

At the search height, adjust the 'Tuner' control towards 'Metal' until you hear a slight audio 'hum' at the Threshold-of-sound. This is what we simply call a Threshold Tuned setting and you want a slight audio 'hum' and not Tune it to be too loud. Then, work the search coil to maintain that same coil-to-ground relationship to maintain that proper Threshold setting. It will then respond positively with an increase in loudness when the search coil is moved toward a non-ferrous 'metal' object.

With the 'Metal / Mineral Locator' you could adjust the Tuner control to the silent 'Null' area, then select to find non-ferrous targets by adjusting the Tuner one direction toward 'Metal' to establish a Threshold hum and try to locate non-ferrous objects, or adjust the Tuner control toward the 'Mineral' side to get a Threshold hum and then search for non-ferrous objects. That could be used to find black sand pockets, iron nials or other ferrous-based metals.

I swing a can of compressed air over the coil and it sounds off. I swing a 9v battery over the coil and it sounds off. But, I swing a clad dime and it nulls, or the threshold goes silent. Exactly opposite of what I expected??
The 9V battery and many other objects we might use as sample targets are made of some type of magnetic (mineral) metal such as steel, iron or nickel (the metal, not the US coin). Usually, the 9V battery housing and similar metals will cause a TR that is Tuned to the 'Mineral' side to respond positively, therefore a non-ferrous object, such as a common coin, will be a negative responding 'Metal' target. They will hull and the Threshold will decrease even to the point of going silent.

I do not see the 'Metal - Mineral adjustment directions on your Tuner knob, but many low-end models only had that proper Tuning information described in the Operator Manual. If your TR is properly equipped and functions correctly, you had the Tuner knob adjusted to the Mineral side and that's why it signaled positively on the 9V battery and Nulled on the coin.

The first thing to do to verify your TR is working properly is to check the Tuner adjustment:

• Rotate the 'Tuner' know fully counter-clockwise until it stops. The audio might be very loud.

• Now, rotate the 'Tuner' control clockwise until the audio reduces to a Threshold setting and then Nulls to silence.

• Continue adjusting the 'Tuner' control clockwise until it starts to make a slight audio Threshold hum and continue to fully clockwise which should be loud.

• Then, adjust the 'Tuner' control back into the silent Null zone.

At this point you will know if your detector is working properly or not. If you adjust the Tuner control and find a 'Null' adjustment zone and can turn it clockwise or counterclockwise and adjust into an audio zone, then you have a Metal / Mineral Locator. All you have to do is determine which direction, left or right, you need to adjust from the Null to adjust to get a positive response from a Metal sample, such as a Clad Dime, or a Mineral sample, such as a Iron Nail.

Once you have determined that you can then adjust the Tuner for a proper light audio Threshold hum to search for coins and jewelry.

If your model only has a Null Zone and turns only one direction into an audio range but only signals positively on ferrous objects, then I believe you have a defective unit because almost all single-direction tuned detectors were designed to shift to the Metal side for Coin Hunting and similar applications.

I've put it up for the evening, but plan to fiddle with it some more tomorrow. I need to spray some cleaner in the sensitivity pot as it is making all sorts of racket.
Before you spray any tuner cleaner inside, do the above test with the Tuner control to see if you have a Null center adjustment and can tune an audible signal both left or right from Null, then figure out which direction is required to signal on a US coin (Metal).

Any of you tenured detectorists got a recommended start up procedure for this thing?
Yep, I just gave it to you.

I'm assuming I would use the tuning knob for ground balance, then use the sensitivity knob for threshold as it gets louder as you turn it clockwise.
Incorrect assumptions.

Your detector doesn't have a Ground Balance adjustment setting. It is a straight TR, non-discriminating model. The 'Tuner' control is used to find the Null zone and then adjust to 'Tune' a proper slight-audio Threshold hum.

The Sensitivity control is simply used to adjust the Sensitivity in order to help handle any ground mineral problems that make it perform too radically in higher mineralized soils. In that case, you reduce it to help control the reactivity to any coil changes from the search height.


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Subject Author Views Posted

Vintage TR machine question Attachments

GA1dad 260 September 27, 2018 08:41PM

Re: Ray Jefferson Model 200 Treasurer Attachments

GA1dad 210 September 29, 2018 07:50PM

GA1dad, clean the 'pots' and try it again.

Monte 176 September 30, 2018 07:13AM

Re: Ray Jefferson Model 200 Treasurer

WM6 160 September 30, 2018 06:19AM

Old-time 'conventional' TR's are interesting. eye rolling smiley

Monte 160 September 28, 2018 07:02AM

Re: Old-time 'conventional' TR's are interesting. eye rolling smiley

GA1dad 149 September 28, 2018 09:00AM

Re: Old-time 'conventional' TR's are interesting. eye rolling smiley

WM6 147 September 29, 2018 02:43PM

Re: Old-time 'conventional' TR's are interesting. eye rolling smiley

WM6 162 September 28, 2018 08:33AM

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