Distorted Transmit Audio / RF Issues & Random Weirdness

GM7VSB

Recently my Flex 6600 started behaving a little flaky with numerous random issues and occasional shutdowns with flashing red light showing software error on the front panel. I attributed this mostly to me making lots of changes in antenna configurations whilst setting up a Array Solutions switch.

Most of the config changes were based around what I thought was an RF issue, I swapped the switch for a 4o3a 8x2 AG but the problem did not go away. I've removed the switch and ran a completely separate length of new LDF450 direct to the main station antenna, the issue persists. The antenna is a A3S tribander and SWR at worst is below 1:1.5 but this is also present when driven into a dummy load.

Checking with a local station, my audio has a very slight RF'ish tinge to it at low power and is unintelligible when raising the power to 100w. At best my SSB transmitted audio is muddy, thin and exhibits low average power.

I've tried to EQ this out but that didn't work. I swapped the cable on my Radiosport headset for balanced input and replaced the M207 element for a M208 to get more bottom end but it doesn't help. Even the FHM2 hand mic sounds awful. Using an AKG CK33 podium mic on the PC input sounds better but is still awful. This problem appears to be independent of audio source and they all exhibit what seems like RF on the audio.

CW received on a second receiver sounds ever so slightly warbly.
Occasional band changes result in a very high noise floor (-80dBm vs -116dBM typical) and this only clears by closing and re-opening the slice.

I have 2x 30amp Linear PSUs, both bonded to the main station ground and everything on the bench is individually bonded to the main station ground with the shortest leads possible. I've double checked resistance to ground across every possible combination of connection in this setup with the worst case being a tiny fraction of an ohm.

I've added ferrite cores (Fairrite Type43) on every single lead that goes to or from the 6600 including the radiosport headset and AKG podium mic. My network also has the same cores at either end of every ethernet cable in the house.

Swapping to a FTDX101 on the same setup, produces crisp clear audio and solid CW tones. With 50w output on either radio, with a local station making recordings the FTDX is several S points up on the 6600 and the 6600 audio is poor.

Flex 6600 running SmartSSDR V3.1.12



I'm thinking this is a hardware fault, but would appreciate any suggestions of a cure before shipping the radio back for service.

KD0RC

You might want to try transmitting 100 W into a dummy load while listening on a separate receiver.  If the problem goes away, it is likely RF getting in somewhere.  If the problem persists, start ungrounding things, as it may be a ground loop issue.  If that does not help, then it may be an issue in the radio itself.
73,
Len, KD0RC

GM7VSB

Len,
Yeah, tried that, even at 1w it persists regardless of being grounded or not.

RoyS

Jason, I had a similar problem when I rearranged my shack. I had carefully moved my coax cables into a nice compact bundle. That was the wrong thing to do. Really strange things happened when i transmitted. I cut open the bundle and separated all the cables. I now have a spaghetti bowl of spread out cables. But, now I don't have any weird things happening when i transmit.

Good Luck,

Roy -W5TKZ     

DL4RCE

Do you use a 10MHz external reference? Volker, DL4RCR

GM7VSB

Hi Volker,
No.
I do have one here, but it's not used with the Flex6600.

HCampbell WB4IVF

“Recently my Flex 6600 started behaving a little flaky with numerous random issues and occasional shutdowns with flashing red light showing software error on the front panel.”

 Counting the number of red flashes may point you in the right direction [edit: you mentioned the flashes indicate software error so it looks like you already did that] .  Also, you might try resetting the radio if you haven’t done so already.  See excerpts from the manual below.

Howard

 ----------------------

 Error Conditions

Certain hardware and software error conditions cause the radio to stop operating and display an error code by flashing the Power button light as follows:

 • One red flash: Fan malfunction

• Two red flashes: Software crash

• Three red flashes: Boot failure

• Four red flashes: Input power over voltage

• Five red flashes: CPU overcurrent

• Six red flashes: Input power under voltage

 In the case of a software crash, the error code repeats for about 15 seconds, then the radio will reboot. In the other cases, the error code repeats until the Power button is pressed, then the radio shuts down. An additional press of the Power button is needed to restart the radio.

 Reset Procedure

With the radio powered off, press and hold down the power button for approximately 5 seconds until the Power LED flashes white, then release the power button. The radio will start and will set all of its internal settings to their default values.

DL4RCE

Ok, had some problems with distorted audio with that. Good luck in finding the root cause.

Volker

DL4RCE

Please also check if the PSU voltage is fluctuating. Had some problems here where the voltage dropped and than the Flex went "red blinking".

Volker

Bob Needleman

Jason - remove everything that you have connected downstream from the 6600. Just connect your PS to the Flex (with as short a DC cord as possible) and a short piece of coax to a dummy load. Listen on your 2nd receiver and see how that sounds. If you're still getting distored audio (and CW?), then there's a problem in the rig. One other suggestion which I didn't see you mention, was installing a common mode choke in the coax line, at the point where  it comes in the shack (eg. right after an external ATU if you use that, or amp). That might help clean things up for you if you're getting RF in from outside (a common problem with multiband ants, like OCF dipoles, etc). 
Bob K3AC

HCampbell WB4IVF

Agree.  Voltage drop checks at the radio under load  may reveal a problem that resistance measurements miss. 

Howard

GM7VSB

Hi Roy,
Fully understand this, but with nothing but the DC Lead, Ethernet and short jumper to the dummy load I'm not sure I could make a spaghetti starter never mind a full bowl :-)

GM7VSB

Thanks Howard,
Yep, 2 flashes repeating a few times and then it restarts on its own. You've kind a got to be quick to catch this.
Tried a few resets, admittedly without removing DC. That's on my trials list for this evening.

GM7VSB

Hi Volker / Howard,
Confirmed 100w output (SSB or CW) voltage drop at the PSU from 13.43V to 13.42V (only 0.01v). The cable is short but I also confirmed it drops the same at the radio end too.

I did notice that the Powerpole looks to have a shoddy termination. I've had a good pull at it though and can't get he cable to dislodge from the crimp. I'll remake that cable later this evening though to be certain it's good.

HCampbell WB4IVF

Some folks have resolved shutdown problems by increasing PS voltage a bit higher than the nominal 13.8v (Flex voltage spec is 13.8v +/- 15%). 

 Howard

on5po

Hello everyone,

I finally solved my problem of distortion of my audio on my flex 6700,

I bought a Yaesu M1 microphone, which did not solve the problem, but which allowed me to use the XLR and the ptt separately

73 ON5PO, Janny

The second phase is to connect the M1, in "XLR", on my 6700 there, its been fabulous, the difference,

it is regrettable that only the 6500 and 6700 has the "XLR"

73, from on5po, Janny

GM7VSB

Doing a full factory reset (with power removed) and not reloading profiles helped with the random shutdowns.

I'm still not convinced I've cured the audio issues, but my findings suggest that adding EQ on the high end of the audio spectrum was causing distortion which sounded like RF. The high end power in the audio was reducing the average talk power.

I've now adjusted the EQ to add no more than +2 on the high end of the scale, reducing everything else to compensate and find that the audio is much improved.

Roger Hartel

Doing the full factory reset, if you removed power by disconnecting the power pole may have helped the issue for an unexpected reason. If the power poles developed internal resistance due to Fretting Corrosion, removing and reinstalling the connector may have helped temporarily. The power poles use tin plated connectors and thus are vulnurable to this type of corrosion. Google the name to find more.

The corrosion causes layers of tin oxide to form at the interface causing contact resistance to increase over time. Tin oxide is the material used in metal film resistors.

Voltage drop across the connector would increase on modulation peaks.

When you disassemble a connector with the issue you see black marks at the contact points, that is tin oxide.

500,000 color tv sets with plug in circuit boards, and 500 pairs of mated tin connectors per receiver was part of my learning experience.

John KB4DU

You mentioned high end boost in the transmit eq. Normal voice intelligibility is concentrated in 300 to 3000 ha. If the highs are boosted it is easy to gently voice peaks beyond the transmit bandwidth. General rule is to cut before boost. I use a transmit bandwidth of 300 to 2900rather than the Flex default of 100 ha.

John KB4DU

Dang auto corrupt. Should be “generate” voice peaks.