How Does the FT-7800R Squelch Work?

[WILLIATY]

I've just gotten my ticket and I'm in the process of picking out my first radio. One of the radios I'm considering is the Yaesu FT-7800R. However, this radio is slightly confusing in that it has both a squelch knob on the face AND a squelch setting in the menu system. How do these two controls interact? Are they both doing the same thing? For instance, if I have the menu-based one set to S7, does that mean that I'm really only doing anything with the knob-based one if I have it set to a higher strength than S7?

Or do the function in different ways? Is one actually attenuation/RF Gain?

The radio (CB) I'm using now has both RF Gain and Squelch. In the noisy areas I frequent, turning the RF Gain down is usually more important than turning the squelch up.


Basically, help me understand what the heck the 7800R is doing with 2 squelch controls.

Thanks!

[K0BG]

Like most FM radios made today, you have several options with respect to squelch. The following is a little more complex than I present it, but I think you'll get the idea.

There is digital squelch and sub-audible squelch. These can be set on transmit only, receive only, or both. Typically, only one type is used for any one given repeater (frequency).

When they are set for transmit, the transmitted code or tone is sent with each transmission thus "keying" the repeater. In this case, if they are not set for receive too, you hear all of the transmissions from the repeater.

If you have a specific digital code set up, then the only transmissions you hear are the ones for you.

Most of the time, sub-audible tones are used to minimize interactions between repeaters which may be on the same frequency and/or reduce intermod trips.

The front panel squelch knob essentially sets the minimum signal level required to open your receiver so you can hear any specific transmission.

As I said, there is a lot more to it, but this should get you started.

Alan, KØBG
www.k0bg.com

[KB1LKR]

In the case of the recent Yaesu's the regular squelch functions on received signal strength (somewhere in the IF signal chain?) the more you turn up the squelch th emore signal strength you need to open it and hear, but it's qualitative, not "calibrated".

The RF squelch menu function offers the ability to set the squelch lever based on the displayed S meter reading -- e.g. set it to "S-6" and for any signal less than S6 on the radio's s meter you'll hear nothing.

It appears that the squelch knob also has some effect when RF squelch is on too, but don't recall the details in the manuals (FT-1802 & FT-60r) nor in actual practice, as I generally just use the regular squelch w/ the knob.

Note too, some radios have *no* squelch knob, but use an arbitrary menu function instead, e.g. 0-10 where 0 is like full CCW, and 10 is like full CW on a knob. Same standard squelch function, just menu set vs. knob set. I'm partial to knobs, but that may be just that I'm a traditionalist (= stubborn & set in my ways), but other than ease of access either should be equivalent.    

Tone (or digital code) squelch, as Alan mentions, is not a function of signal at all, but presence (or absence) of a subaudable tone (or digital code). If the correct tone (or code) is present AND the signal's strong enough to open the regular squelch you'll hear something.  

[KF6IIU]

I have never seen a technical explanation of this either - the FT-60 has the same setup.

However, then FT-60 seems to "pop" less on nuisance signals like intermod and weak unreadable FM signals when I set the "menu" squelch to S2 or S3 and then use the knob to vary the squelch level.

However, the FT-60 will still receive open-channel static with the knob fully CCW and the menu squelch at 2 or 3, so my interpretation is that he knob squelch sets the level overall and the menu squelch sets a level at which the squelch won't open, if a signal is actually being received and registering on the S meter.

[KL2MV]

i believe on my ft8800r you can set the menu squelch to whatever you want, but than you must set the manual knob to full.
cut/paste from the ft8800 manual:
 A special “RF Squelch” feature is provided on this radio. This feature allows you to set the
squelch so that only signals exceeding a certain S-meter level will open the squelch.
When setting up the RF Squelch circuit for operation, note that you may set the RF Squelch
independently for the “left” and “right” sides, using the following procedure:
1. Press the [SET] key momentarily to enter the Set mode.
2. Rotate the “Main” band DIAL knob to select Menu #32 (RF SQL).
3. Press the “Main” band DIAL knob momentarily, then rotate the “Main” band DIAL knob
to select the desired signal strength level for the squelch threshold (OFF, S-2, S-5, S-9, or
S-FULL).
4. Press and hold in the “Main” band DIAL knob for 1/2 second to save the new setting and
exit to normal operation.
5. Finally, rotate the SQL knob fully clockwise.