Tried out the X35 9 but found I had to deal with more emi chatter than the HF coil. Can tune the HF 9 coil to 13-14.4khz. One interesting thing on the Orx they have the X35 coin fast preset at 17.3 Khz whereas they have the HF coil preset for coin fast at 14.4khz. That seems slightly odd because I would think the HF coil would favor the higher frequencies. And in air testing the HF 9 it seems to favor the 14.khz but I know air testing can be off.
Agree, the X35's naturally tend to pick up more EMI at their lower frequencies (4 and 8 khz) which is really true of most detectors that operate in that range, but I too found them to be more chatty even in the higher frequencies and it is probably a tad worse with the 11", but I like the ground coverage of the 11" when needed. The X35's are really quieter than the original LF coils and XP released a SW update (5.1) that fixed super chatty behavior when they were first released. 5.21 is the current latest firmware rev, I believe and that fixes a battery drain issue in the headphones when they are "off".
Really have not found any XP coil I like better than my round 9" HF coil.
Regarding the ORX presets:
The HF coils perform pretty consistently across the board, regardless of frequency (i.e., they don't favor a frequency, necessarily, though I tend to "think" my 9" HF coil runs optimally at around 28 khz). However, there is a physics based performance limit based on frequency and the conductivity range of the targets and a natural "programming" limit that comes into play with the pre-programmed preset on the ORX. On the Deus, XP is kind of forced to select preset frequencies that roughly correspond to the X35 presets and then let the HF coils "fall where they may" in terms of the frequency selected for the HF coils. I am not sure how they do it on ORX. Frankly, for any coins program I would have thought they should choose around 12 to 14 khz which corresponds to an approximate common "general purpose" frequency for both coils. Ideally, for high conductor coin depth performance you would normally choose the lowest frequency, but since the HF coil cannot operate below 13 khz, then the coins fast limit of 14 khz makes sense for the HF coil, I would have thought the preset should be 12 khz for the X35 coil, but 17 khz corresponds to the XP Deus Fast frequency preset (which never made sense to me unless you were focused on gold jewelry, not coins). Anyway, it is what it is. If you want high conductive coins on the HF coil, 13/14 khz makes sense, if you want mid-conductive relics, nickels, and gold jewelry - 28 khz makes sense or a higher frequency if you want micro targets or gold (but recognize depth will be severely limited).
The following is for Deus users and how to set up the various custom programs to accommodate both the HF and X35 coil frequency ranges/presets:
Regarding the frequency presets for the different coils, that is just a function of the coil, since there can only be one frequency chosen for the preset or custom program, e.g., 18 khz., the coil is going to default to the frequency closest to the preset. The presets are typically based of the LF or X35 coil frequency choices, so since 14 khz is nearest the 18 khz chosen in the preset, the HF coil will program itself to that frequency. If you change the preset to around 25 khz then both the X35 and HF coils will set up to 25 or 28 khz respectively. Note that each coil has slightly unique decimal frequency base presets based on its final factory winding configuration - this is determined by factory testing. "18 khz" can result in 17. 3 khz on one coil and 17.5 khz on another coil. When I set up my custom programs I try to use frequencies that roughly line up with both my X35 and HF coils so that I don't have to have unique programs for each coil. Therefore, I typically have a "low frequency" version and a "high frequency" version of each custom program that I use the most (typically pitch tone, 5 tone, and full tone and then some gold field programs - which results in about 7 or so custom programs but only really 3 variants the differ only in frequency). I typically set the "Low frequency" programs to around "12" khz (12 for the x35 and 13 or 14 for the HF) and the "High Frequency" programs to "25 khz" (25 for the X35 and 28.8 for the HF) that way the X35 and HF coils will behave about the same frequency wise, for a given program.
