Apparent engine noise only when squelch is active.

[144inBama]

Sitting in the truck today, I noticed when the squelch is active, I have engine noise but here's the part that makes me wonder.....With the volume all the way down and the squelch off, there is no noise, with the volume still down and I slowly turn the squelch up, as soon as it reaches the peak of the noise floor (becomes active), the noise returns. The radio is the 959B, where exactly would this issue stem from or is it just a "thing" with this radio?

 

[Slowmover]

Tried to replicate, but can’t.

Must be red dirt conductivity.

 

[144inBama]

The receive is excellent so no complaints there, it's that "humming" when it's active that bugs me. If I turn the RF gain down to quiet the noise floor, there's no noise either, JUST when I use the squelch. I replaced both of the large caps(1000uf) with 2200uf then 4700uf in hopes of eliminating it, the only thing that did was get rid of the light flicker/dimming on transmit, which I'm good with too. I've never ran into this problem, in this form. It usually has the noise regardless of how the squelch is set/used.

*edit to add*
None of my other radios do this when used, Connex 3300, 99v2, 29LTD, 980SSB, only this one, the 959B.

 

[Slowmover]

Mine runs wide open most of the time (call that 0400-1600 daily).

“Difficulties” have been noise sources separate from vehicle, in main.

“Heard” the alternator the other morning, ANL eliminated it. Haven’t heard before or since (in three weeks since installed).

Have upgraded coax jumpers twice, that may account for some of both solution & problem.

Have gone thru antenna stud/mount four times and about to do it again. (This is no longer a temp install).

Can’t say I’ve ever tested the way you have until now. (TX light solid).

RF Gain & Squelch don’t much alter RX hiss until it’s eliminated. So I leave them off.

Adjusting Radio Volume against DSP SPEAKER Volume is about it. That’s the sweet spot to adjust on this rig.

Have to be cautious in that as you can knock your ears off in rural areas by adjusting both those a little too high, then, SOMEONE SPEAKS.

.

 

[cralt]

Sitting in the truck today, I noticed when the squelch is active, I have engine noise but here's the part that makes me wonder.....With the volume all the way down and the squelch off, there is no noise, with the volume still down and I slowly turn the squelch up, as soon as it reaches the peak of the noise floor (becomes active), the noise returns. The radio is the 959B, where exactly would this issue stem from or is it just a "thing" with this radio?

Do you have an external speaker? Try unplugging that.
I have ferrites on my antenna, power, and speaker leads. Even a small clip on one for the mic lead.

 

[144inBama]

Do you have an external speaker? Try unplugging that.
I have ferrites on my antenna, power, and speaker leads. Even a small clip on one for the mic lead.

No external speaker, I have ferrite on the power wire and mic cable. Like I said, this is the only radio that does it and nothing changes but the radio when I swap. I'm wondering if it's a weak cap in the squelch circuit.

 

[Cabover Bob]

Recently switched from the Conex 3300 to an RCI 6300F150 and noticed some additional noise with my led beacons on and dramatically more noise with led spotlight on. When I turn squelch up just past the sound floor, I am getting some additional noise as big rigs pass by in the opposite or same direction as well.

I will admit that I have power for lights and coax running together, but never had any of this until the RCI 6300F150 was put into service.

Ferrite clip ons on power/ground/coax near the radio, and will be adding a 40a noise filter when Fleabay delivers. I seem to have seen a slight increase since installing an external speaker last week, I will try Cralt's idea and disconnect to see if there's a relation. I will be rerouting much of the wiring in the next few days, hopefully get it all sorted out.

I've asked drivers if they hear the alternator whine when I transmit, they all said no, so I don't really think that I need any ferrite on mic cord.

Is there any reason to ground the radio chasis ? Sirio 5000 is mounted to pickup headache rack, braided ground jumpers from mount>cab/mount>headache rack/headache rack>bed. Still need to install bed>tool box and hood>fenders & cab.

 

[Handy Andy]

No external speaker, I have ferrite on the power wire and mic cable. Like I said, this is the only radio that does it and nothing changes but the radio when I swap. I'm wondering if it's a weak cap in the squelch circuit.

You're close...

In fact there may be one used to "silence" the "scratchy noise" from the pot on the front panel...

If the Faceplate has been pulled, this opens the ground loop / shield that the radio originally had.

This may not be from you - it may be from the shop verifying it works before they sent it to you.

Anyone that disassembled the radio - if you don't put it back exactly the same way...you get the potential for a noisy spot on the front panel ripe for noise.

So let/s take a look at the 959 - and hope like hell you have similar...

Q44 is your SQ amp - the one that actually silences your Audio RX line. So noise injection here, would come from RX which it doesn't seem to - only when it ON - so you'll need to take a look at J5 on your board, it handles the GNF and SQ knob. Be sure it's seated

The noise that can still inject AFTERWARDS, is from your Talkback - that can come from open removed limiter, or poor loose connection to the Talkback pot which goes to a centralized connector by your Audio Amp...

Another look...


Ok, it's a 949 -
But it's the best DIRECT example I can give you​

So potential INJECTION noise sources are AFTER Squelch in the line - so the main culprit seems to be Talkback - the last stop on the line to the audio amp...

Why do I say Talkback?

Well, your SQ function is working, but looking at the schematic, you have a resistor then the INJECTION point for Talkback audio. So I'd suspect the Talkback area, and any knobs or switches involved in the Front panel that any parts and headers have been molested.

The problem is the noise level, is due to how all the pieces that give you your features' - are installed in a hierarchy in step with the line starting back at the VOLUME control - SQ-uelch, TB (Talkback) so your last line, is the most suspected to be the one causing you the grief. That being Talkback.

Best way to check, pull the header from the TALKBACK (purple arrow) Noise gone? There's your source for the noise.

 

[144inBama]

Thank you Andy, I'll give that a go. If it is the Talkback, no problem because I never use it anyway so leaving it disconnected is a non issue.

 

[Handy Andy]

IF removing the Talkback header, and noise persists, then the only other thing you can do is what I have suggested to @Shadetree Mechanic in a recent post...

Yes, that does mean hooking back up the limiter to stop the noise from leaking thru the Mic wire that is still live.

https://www.worldwidedx.com/threads/galaxy-dx86v-mods.256522/page-3#post-771849

Another option, but not as effective is to SHORT out the mic line LIVE wire - to ground when in RX mode. It's easy enough to do - just some powered mics don't like having their output line shorted.

Typical 4-Pin Galaxy Wiring.
This presumes they Hardwire Mic Element DIRECTLY to OPEN in RX.
This forms a Noise Pickup loop.
Now let's modify the YELLOW wire
to make it short to GROUND in RX ONLY
(You won't hurt it...)

What you do,
Install a simple jumper from unused yet connected to Audio MIC live wire
and SHORT IT DIRECTLY to ground - when and only when IN RX Mode
Or when the Plunger is out.​

The above is one of the better options when you decide to remove the limiter. At least you have noise picked up by the handset getting sent to ground to attenuate any if it exists - only when you're in RX mode.

Simple enough to do - nothing to lose to try it.

 

[Slowmover]

Recently switched from the Conex 3300 to an RCI 6300F150 and noticed some additional noise with my led beacons on and dramatically more noise with led spotlight on. When I turn squelch up just past the sound floor, I am getting some additional noise as big rigs pass by in the opposite or same direction as well.

I will admit that I have power for lights and coax running together, but never had any of this until the RCI 6300F150 was put into service.

Ferrite clip ons on power/ground/coax near the radio, and will be adding a 40a noise filter when Fleabay delivers. I seem to have seen a slight increase since installing an external speaker last week, I will try Cralt's idea and disconnect to see if there's a relation. I will be rerouting much of the wiring in the next few days, hopefully get it all sorted out.

I've asked drivers if they hear the alternator whine when I transmit, they all said no, so I don't really think that I need any ferrite on mic cord.

Is there any reason to ground the radio chasis ? Sirio 5000 is mounted to pickup headache rack, braided ground jumpers from mount>cab/mount>headache rack/headache rack>bed. Still need to install bed>tool box and hood>fenders & cab.

When I was in Walcott CB yesterday two tanker yankers came in after me. One had terrific LED noise from his 389 chicken (clearance) lights.

Cheap China junk.

I had to leave the parking lot to hear much. (Mines a new Galaxy 959b)

My radio power line is wrapped 5-6 times thru a fat Mix 31 snap-on toroid. 1/2” ID. (See recently updated thread on INTERFERENCE).

Power from BATT (32’ circuit; 6-AWG) goes to an APP dist block. Small ferrites for speaker & amp.
Nothing on mic cord.

— Disconnect coax at radio and only touch center. Re-attach shell and consider common mode current. (See thread on MOBILE COAX CHOKE).

— IMO, can’t hurt to run ground from seat bolt to radio chassis. Ground power at same point.

— RF Bond hood, cab, bed & exhaust (see www.k0bg.com)

I

 

[144inBama]

Disconnected the talkback, no change. I put a 2200uf cap across the speaker terminals and it removed all the noise, it also dropped my volume to a ridiculous level. Tried a 1000uf with the same result. We have some 100 down to .5uf at work so Wed or so I'll try one of those. While in there, I noticed a VERY high pitch whine in the area where the power comes in. It's not affecting anything as far as I could tell and you can't hear it unless the lid is removed so that's a non issue....until it starts smoking or something.