Transducer Slew

A

Anonymous

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Hi

I noticed in another thread it has been mentioned the 12h - 28kHz transducer could be slewed 10kHz.

With 38BL- 15HR is there a range it can be used at (i.e. 10 kHz ) or is it set for 38kHz only?

Thanks
 
Paul,
All the BL 28,38 & 50Khz transducers have a 10Khz slewing range (up/down 5Khz). So if you wanted a little deeper performance you could slew the sounder down and use the CA38BL-15HR at 33khz.

Snips
 
Thanks snips.

1) by slewing it up or down does it change the cone angle at all?

2) In another thread it was mentions you could run the transducer different ways i.e. its a rectangle 160 x210 - turn it 90 deg and it will change which way the cone angle will come out of transducer.
Which way does the 21 deg come out (i would assume 210mm length??) and which way does the 12.5 deg come out?

3) The transducer is used just for bottom fishing deep - which way would you recommend running it (21 deg aft to stern 12.5 wide or the opposite), and why?

Thanks
 
Paul,
I feel that the beam angle would increase with a lower frequency but have conducted no testing along these lines.

Normally the long dimension of the transducer is arranged for/aft for smoother water flow. If the CA38BL-15HR were mounted that way the wide (21 degree) part of the beam would be port/stbd.

Since the size of your bottom foot print doesn't change (just the orientation) I don't see an advantage either way on beam direction for bottom fishing.

Snips
 
Hi Snips,

Further to this topic. I a running a 295 with the 38BL-15HR and have been going through the settings and manual and internet for that matter. I cannot find a good explanation for the frequency choice and frequency control and how and why to use it.

Specifically how it is used and set for the 38 knowing it had 10kHz BW? (Theres stuff in the manual stating it 4 frequencies can be put in for any one transducer, so then why would you need the frequency control to slew the frequency???)

Also how do I know which frequency is being used when sounding as it is not displayed on the main screen etc anywhere?

Thanks
 
I think I have got my head around freq control and freq choice.

However with the 38BL-15HR if I program for example 4 frequencies of 43, 38, 37 and say 33.6

and I have freq choice of HF 43 and LF 38 ( or any other combination of 43,38,37 or 33.6) can I run it in dual freq or is that unable to be done with that transducer?

Thanks
 
Paul,
Your transducer has a pretty flat response curve from 33 to 43Khz so I don't think you are going to see much of a difference. I don't have a 295 available at the moment but I am pretty sure you should be able to program the HF side to use the LF transducer. In this case you could program the LF side for 38Khz and the HF for 43Khz to compare the two side by side.

Snips
 
Your response makes me think I may not have got my head around the frequency control and choice.

Correct me if I'm wrong but with just the 38 hooked up to LF terminal nothing on the high terminal, I use frequency control to set up four different frequencies, which I can change at any time to other frequencies using the frequency control. I then go into frequency choice which gives me 2 options HF (LF terminal) and LF (LF terminal) and I can choose any one of those 4 pre set frequencies for either the HF or LF? Therefore when I switch 295 onto HF it will be the one I selected in frequency choice and when I switch it over to LF it will be the frequency I choose for the LF in frequency choice??

Thanks
 
Also it appears that I am unable to change the bandwidth? There no option to change it in the set up transducer menu. And it gives an option only to slew from 33.6kHz to somewhere up to 45 or 46kHz. Is that because these are the frequencies that are available for the 38BL-15HR?
 
Paul,
If you manually enter frequency instead of entering the transducer type you will be able the set the band width up to 50% of the frequency. So if you set the frequency to 38Khz you will be able to set the BW to 19Khz.

Snips
 
Thanks Snips,

For best results should I not have the transducer type entered in the set up?

Also the 38BL-15HR as you were saying only has a bandwidth of 10kHz so what advantage is there to setting it to 19khz bandwidth?
 
Paul,
Using the transducer type pre-sets the frequency/band-width and tells you what tap setting to use. When you manually set the frequency it allows you manually set the BW to a wider setting. Is this an advantage, yes and no. Setting the 295 up this way just gives you a wider range of frequencies to look at. At the end of the day I still think you are going to find you end up right around 38Khz.

Snips
 
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