Icom R8600 Step Size Rounding Question

MDScanFan

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I could not figure out a good title...

Let’s say my tuning step size is set to 5 kHz. When I use the touch screen to select a signal on the spectrum scope the selected frequency may be something like 118.24154 MHz. On the 7300 when I then move the tuning knob it automatically rounds the frequency to the tuning step, such as 118.240 or 118.245 MHz if I go down or up. However, with the default settings the 8600 goes to 118.24054 and 118.24554. This is a annoying when the signal I most likely want to hear is on the rounded step size (ex 5 kHz). I have to double tap the frequency and then tune for it round the frequency to the step size.

Is there a way to get the R8600 to do this rounding automatically?
 

rumcajs_tr

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I think this is done by intention as the R8600 can do even very non standard steps, which 7300 can't do. For example - here in Czech Republic, we use "odd" 20kHz steps in 400MHz band, so the frequencies are as: 451.010, 451.030, 451.050,... so I tune to 451.010 and select 20kHz step and this way, I can tune (scan) this. If the frequency would be rounded always from xxx.000 frequency, this would not be possible and do only 451.020, 451.040, 451.060, etc...
 

MDScanFan

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I agree that on the R8600 a user can select any (reasonable) tune step. By rounded I mean rounded to the selected step size.

The issue is when I manually select a desired signal by hand from the spectrum scope the frequency is close but never exact. In this situation, with the 7300 it then automatically rounds the frequency to the tuning step when I use the tuning knob. The R8600 does not do this by default.

I am not sure I am explaining this well. Could someone with a R8600 try this to let me know if they have the same issue?
 

prcguy

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The problem is the 8600 or any receiver will receive a signal quite a ways off frequency and upwards of several KHz and during a frequency search it will stop well before the center frequency unless the step size is greater than the range where it will detect the edge of a signal and break squelch. During a frequency search the radio has no way of knowing what radio service you are searching and what step size to use as that changes constantly even within the same band.

Actual channel spacing of radio services are usually at least 12.5KHz or 15KHz except for some digital modes where they can stuff them maybe 6.25KHz apart, otherwise the commercial radios would get interference from adjacent channels. That becomes a problem when channel spacing can change to 5KHz or 2.5KHz at the edges of one type of radio service and the beginning of another even though you will never find actual channels spaced only 5KHz or 2.5KHz apart.

On the R8600 or any scanning receiver you have to carefully choose your search step increments to avoid having the radio stop prematurely and off frequency of an active channel and that will be more than 5KHz in all cases or you will experience what you are seeing. Its normal for the radio to do what you describe if you put it in a situation where the search steps are so small that it will open squelch before landing on the actual center frequency.
 

MDScanFan

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prcguy, this is a separate issue than what I posted in a different thread about searching - I found out it was a user error on my end.

Can someone please try this for me:
- tune to 100.000000 MHz
- select a step size of 100 kHz
- on the spectrum scope double tap a nearby signal. Let’s say that picks something like 102.123456 MHz.
- rotate the tuning knob.

Does it round the resolution of the frequency back to the step size of 100 kHz? Say, 102.100000, 102.200000, etc.

Or does it retain the lower frequency value as you tune. Say, 102.023456, 102.223456, 102.323456, etc.

Thank you
 

rumcajs_tr

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The solution in this case is to to tap the kHz part of frequency (so the arrow disappears) and then tap it again (so it appears again) - after that, turning the tune knob rounds to steps again.
 

MDScanFan

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So it sounds like it is the same way for you. I was hoping I was doing something wrong.

You are correct that the double tap of the frequency works, and that is what I do. I just find it very tedious to take that extra step and if I am trying to quickly navigate to a signal that may disappear it is just lost time. And I can’t think of a circumstance where someone would want to retain these “random” frequency digits after they have specified a desired tuning step. This is a feature oversight for Icom.

The 7300 rounds automatically. On HF I find the 7300 so much more pleasant to tune for this reason.

The solution in this case is to to tap the kHz part of frequency (so the arrow disappears) and then tap it again (so it appears again) - after that, turning the tune knob rounds to steps again.
 
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