Fan noise 8400M

Erik Carling EI4KF

I took delivery of a new 8400M today. I am struck by the fan noise compared to my 6400M. This is after boot and the radio is running on receive. There is a constant medium pitch noise which to me is akin to the sound heard when near an electricity sub station. Not as loud as that of course but of that type and rather like a constant drone.

As I transmit and the PA temperature increases, the fan speed increases and the droning sound quickly decreases and is replaced so that all I hear is a faster running fan that is no noisier and actually less abrasive to listen to.

Measuring the noise with my smart phone, whether accurate or not, shows circa 40dB which is not much.

Before I take up Help Desk time, can anyone provide an opinion on whether this is normal for the 8000 series radios please?

If there is any solution the user can achieve without sending the radio away I would also be glad to know of it. I am not keen on returning it to the retailer because they just had my new PGXL for warranty repair for 8 weeks, of which 4 weeks were taken up by no activity by them and only an email to the company's MD got it moving. I cannot face that again.

Thanks,

Erik.

Erik Carling EI4KF

In the absence of answers or advice, apart from Mike's recommendation to open a Ticket, I did just that.

Erik Carling EI4KF

My anti vibration fan mounts and vibration isolation pads arrived today. On taking off the top cover, I could hear a ticking sound referred to by others on the Forum. In my radio this was due to a blue cable that runs across the face of the fan and was just slightly coming into contact with the blades. Because the fan was not mounted properly and not square to the chassis, not every blade touched the cable. This caused a clicking or ticking which was easily remedied by taking up the slack on the cable and securing it to some other cables on the left hand side. That issue solved.

Flex use half size rubber fan mounts so I replaced those with full size ones that pass right through the fan mount holes. Then I found what vibration remained could be stopped completely with an anti vibration pad between the right side of the fan and the chassis when the bottom case cover was in place. Just touching the fan mount with a finger and moving it fractionally left stopped the vibration noise. There is something inherently amiss with the mounting.

Noise level when I reported the issue to Tim Ellison was 51dBA at idle on receive. He advised that the spec should be 30dBA, however my 6400M is at 35dBA and that had never worried me. My 8400M is now at 37dBA and is perfectly acceptable.

I would have preferred to have used a Flex sanctioned, and better still supplied, remedial kit but they only wanted me to ship it to Germany to someone who has no idea about it and I doubt has any official noise suppression material or remounting instructions. But anyway I did it myself instead.

There do not seem to be, unless I have overlooked them, any temperature specifications. The radio is running at 25C in a room temperature of 22C. So I am of the opinion that there is no negative side to my work and only the great positive that the radio is now as it should have been when delivered.

Erik.

Mike-VA3MW

Hi Erik,

Please feel free to follow up with the helpdesk if needed. We get it when it is something that impacts your operating pleasure.

By the way, in a separate project, I had to rent a calibrated noise pressure meter, and out of curiosity, I compared it to my iPhone. Surprisingly, it was within 1dB—pretty impressive for a phone.

Since this is a new shipment/radio, it is taking priority at the moment.

For others who were curious, I wanted to provide some context for what 40dB of noise actually sounds like. I asked ChatGPT for a simple explanation, and here's what it offered:

"It’s about the level you might find in a quiet library, a peaceful suburban neighborhood, or a calm office environment. While not silent, it provides a gentle ambient sound. In terms of loudness, it’s significantly softer than a normal conversation."

Also, just to clarify—yes, the fans in the 8000 Series radios do run even during receive. This is intentional to cool the FPGA and other processors, which are significantly more powerful than those used in the 6000 Series.

We understand that service times can feel unpredictable. They vary based on several factors like staffing and current workload, and unfortunately, that can fluctuate month to month. We truly regret that it sometimes seems like communication goes quiet during the repair process. It’s not our intent—we’re simply working through the queue as efficiently as possible and don’t always have the bandwidth to respond to every update request in real time. We recognize this as an area for improvement and are actively working on ways to do better.

Thanks for your understanding and patience.

73, Mike

Erik Carling EI4KF

Hi Mike, thank for your reply. I have no problem providing understanding and patience. I would say that my 'phone's noise meter grossly underestimates the dB generated by my 8400M because it is greater than that of a library or calm office. I had read elsewhere that the 8400 fan noise is more than the 6400 and that is ok with me. It is the type of noise that is bothersome. If I press down on the outer top panel I can reduce that noise temporarily. It is as if there is some kind of resonance or vibration or something unusual anyway.

I will wait to see if there are helpful replies providing information and / or advice and, if not, I will open a Ticket.

By the way, the PGXL saga had nothing to do with Flex. It was bought and had to be returned to a European retailer. It is likely though the same resource restrictions as you quote also apply to them. It is not a complaint, just that the thought of returning another Flex product for which I had just spent a lot of good money on only to get a 2 month long hiatus of unit absence and related irritation is not optimal.

Erik.

Mike-VA3MW

Hi Erik

No worries and I am fortunate enough to see both sides of the business at the same time. I would like to think that in all cases, they are trying to do all they can.

73

Arnold Goldman

i was just wondering the same thing ; finally got the 8600M working with the tgxl and pgxl and hearing a noise like a fan hitting the cabinet?? i opened up a help ticket

Erik Carling EI4KF

I hope you have better luck with the answer than I did. If you are in NA you are likely covered. Here in EU, you just feel insulted.

Erik.

Arnold Goldman

sent in videos of the noise; i should be covered when i frist got the 6600M 5 years ago the front speaker was dead silent right out of the box; it' been back 4 times; another for display going band and for 2 SD cards tnx

Arnold Goldman

K4QXX

Arnold, I had the same noise in my 8600M. Radio was quiet for the first 7-10minutes when turned on and then a fan kicked in and it sounded like the fan was hitting something. A loud ticking noise. I sent the radio back and the turnaround was very quick. Flex replaced the fans mounts. However, it didn't fix the noise and I had to send it back again. Flex has had it a few weeks (probably due to Dayton) but I am supposed to get the radio back today. Flex said they replaced the main fan. I don't mind fan noise but listening to the ticking, tapping noise from the fan was driving me crazy.

K4QXX

Burch

Erik Carling EI4KF

This is symptomatic of a plague of poor customer service afflicting Flex and hence affecting some of its consumers lately. You got the radio back and it still had the problem. A German customer sent his noisy 8600 to the EU service centre and it came back just as bad. Not much checking of work done.

My 8400M arrived this week, noisy both in loudness and in type - resonance or vibration or both. With less than a day's ownership, I am advised by Flex to send it to the EU service centre. For what purpose since it won't get fixed there?

Flex knew about this problem some time ago. New production will undoubtedly have the fix. But why not existing stock models both at Flex USA and in EU retailers? Nothing was done and they were just left for the poor unsuspecting buyer to discover the issue. Those stock units should have been given the update before sale.

WiMo from whom I purchased it know nothing of any noise issue so instead of a refund will send it to the EU service centre if I return it to them. With the fix known it would be have been a good idea to send a service sheet to the EU engineer. Since that clearly has not happened, I will have to try to determine what this secret fix actually consists of and make the required changes inside the radio myself.

I am insulted and disenfranchised, all because I spent 4000+ Euro on another Flex product. My third in four years and they all have had issues. I should have known better.

Erik.

Arnold Goldman

tnx i am going to try the return fix; the noise is driving me crazy too; sorry in a way I sent back my 6600M otherwise i love the radio

SIINC

I have to make a comment after reading this post over and over this week.

I sent my 8400M back for the fan noise after the first week of receiving the radio back in February. Hard to believe I had to send it back after waiting a year for a new radio from Flex. They replaced the fan mounts, however, really didn't do much to fix the problem. Still annoying and now it developed a ticking noise after the radio has been on for about a half hour. I'm not trying to be nitpicking here, but a device of this level should not have this issue. I'm just totally frustrated with this from day one.

Erik Carling EI4KF

This afternoon a kind soul emailed me this:

"I had the same issue. I used the rubber fasteners that come with computer fans between the fan of my Flex-8600M and the metal plate to which it is attached (a little hot glue to ensure that nothing slips).

I pushed a piece of thicker shrink tubing under the fan (middle of the fan on the base plate) I positioned the shrink tubing in the middle in front of the fan on the base plate with a long pair of tweezers, then lifted the fan slightly and pushed the shrink tubing underneath with the tweezers.

This means that the fan does not touch the rear metal plate or the base plate under which the feet are fitted. I only hear a very quiet sound from the air flow. I did not just have high level noise but also clicking, humming and other noises. All these problems have disappeared."

He also sent a picture of his amended fan mount which shows the use of these

I have no idea how they fit but I found them on Amazon so ordered four. I guess I will figure it out next week after they arrive. I could sound off again about why do I have to do this with a 4000+ Euro radio barely out of its box. Few will care least of all Flex, for if they did they would never had let these issues happen and impact so many buyers. Mike MW though did email me personally bless him. This post is more for SIINC, because mentioned were noise and ticking, in case he wants to consider this fix.

Meanwhile, so that I can actually use my 8400M without it giving me a headache (no exaggeration), I have temporarily put a large wodge of foam between the bottom plate and the desk so that the feet barely touch the desk if at all. What a difference that makes.

Erik.

Trucker

Those will pull through the mounting holes on the metal panel that the fan is mounted on. The tapered end is pulled through the panel holes and the two holes on each of the four corners of the fan. The expanded part will pull through till it stops. Once all the way through, the fan will be tight against the rubber mounts and not touching the metal panel. I installed a new fan in my 6600M before I traded it in ( fan came from Flex Radio) and I used a pair of needle nose pliers to reach the tight places. You will have to remove both the top and bottom covers to get to the fan mounts. There isn't a lot of room to maneuver around. Be careful how you route the power cable so that it doesn't get near the fan blades. In the 6600M there was just enough room to route the cable under the rubber mounting on the top of the fan and then put the rest of the cable through a hole in a metal panel between the PA/ATU and over to the connection on the main board.

James

WD5GWY

Erik Carling EI4KF

Thank you, James. I understand your instruction and will be careful. 73 de Erik.

K4QXX

This is the fan noise that I am having on my 8600M. Sorry, it won't let me attach a sound file but it's very obnoxious this noise.

Arnold Goldman

i sent in sound file to flex dealing with a Mr coos who is very nice and said this noise is normal' i repeatedly told him it NOT the fan noise its a very annoying sound like the fan hitting the case like you guys mentioned above; im going to request to send the radio back; sent my 6600 back for a trade in in a way im sorry but guess they will make good on this; otherwise i got all 3 working well together and am going to try to leave the amp and tuner on stby and try it at my xyl appartment remotely i just didnt want to leave amp on remotely before; tnx for comments above i thought i was crazy

K4QXX

That's what my 8600M sounds like. Like the fan is hitting something. Tapping, ticking sound. That should NOT be normal. I have the volume on the radio up at 80% right now and all I can hear is that noise. I don't care about the woosh sound of the fan, but this ticking noise is like fingernails on the chalkboard. I am sure Flex will figure it out but I don't think it's the main fan as that was what they replaced in my radio and it made no difference.