TGSL DD coil: importance of coild inductance vs resonance frequency?

[Mullihaka]

It has been stated, that the DD coil inductance for TGSL needs to be 6.0mH for TX and 6.5mH for RX, for proper phase relationship.

Is the phase relationship depending only on these inductances?

In other words, if the inductances are somewhat else but I tune the resonances to correct frequency (by means of parallel capacitors), have I already lost the game?

Which counts more: the correct resonance frequencies or correct inductances?

All hints appreciated.

[dfbowers]

You can get the TGSL project to work using a range of different inductances by changing just one capacitor.. In fact, the project does not even use the original coil specs. If things are too far off (tx inductance for instance) the oscillator may not start or run correctly. The most important thing is to get the phasing correct or the demodulators will not be able to sample the rx signal at the correct spot.

[Qiaozhi]

It has been stated, that the DD coil inductance for TGSL needs to be 6.0mH for TX and 6.5mH for RX, for proper phase relationship.

Is the phase relationship depending only on these inductances?

In other words, if the inductances are somewhat else but I tune the resonances to correct frequency (by means of parallel capacitors), have I already lost the game?

Which counts more: the correct resonance frequencies or correct inductances?

All hints appreciated.

The coil phasing depends on two things:
1. The relative frequencies to which the TX and RX coils are tuned, and
2. the mechanical nulling of the coils.

Hence the actual inductances are not overly important to get the correct phase. However, you can easily run into problems associated with (for example) the TX oscillator (non-starting, as already stated), overloading of the preamp, difficulty in finding the ground balance point, and bad discrimination. You should always do your best to adher to the stated values on your first attempt. After you have a working design, it's time to experiment.

[dfbowers]

Mullihaka,
You might want to invest in a copy of ITMD by Carl & George. It has a nice chapter on experimenting with different coils. .. although for the Raptor project.. you can get the idea.
Also, if you read some of Ivconics post, it's very interesting to read about what other coils he has been able to adapt to some of his projects (Fisher coils for instance).
Don.

[ashefr10]

Mullihaka,
You might want to invest in a copy of ITMD by Carl & George. It has a nice chapter on experimenting with different coils. .. although for the Raptor project.. you can get the idea.
Also, if you read some of Ivconics post, it's very interesting to read about what other coils he has been able to adapt to some of his projects (Fisher coils for instance).
Don.

Hi Don, are what can slightly increase the detection depth of my TGSL acting on a part of the map and where? I'd gained about 5 cm if possible with my home coil 27 cm Double D made.