PGXL Noise mitigation + Power ON/Off switch

Sergey KN7K

There are few reviews on eham and few posts here about PGXL Fan's noise.
I understand that PGXL was designed mostly for remote operation.
What about other guys who does not this capability?

After reviewing internal design, I understood that my initial thoughts to change internal Fan's are not going to happen. 
I came up with project to build another enclosure with sound isolation material and place it behind my desk - good project during this Spring isolation.

Notes:
1. I do not recommend it to anyone unless you are familiar with Airflow and cooling.
2. I do it on my own risk
3. Have it up and running from mid of March at full power and several contests.
4. Initially I had 1 extra fan on the back. During contests with legal power Temp would go up to 62 degree with continuous CQ in CW.
   Since than I installed 2nd Fan and now Temp would keep below 60 degree. Details below.
5. Noise measurement compared to Acom2000A, both sit from me about 30" and after installed in encloser  and placed behind the desk.
    My Radio shack would not measure below 50db, so it will be "Low"

6. Initially I was planning to install small Plexiglas window in front of PGXL LCD screen, but did not do it yet. Currently it is not needed, maybe later.

External Enclosure design:
1. Wooden box built from Home Depot material.
2. Most important points - Front bottom has opening 2" wide for incoming air!
3. All sides have about 1" clear space, top has about 2" clearance
4. Four legs elevated about 0.5-0.7" above the floor - this is to ensure air flow from external Fan's.
5. Two 12cm Fans (12v) running ALL THE TIME at 8.5v to keep them quiet!

Images from beginning to the final (pretty much self explained)



Front top view



Back view


Top


TOP VIEW before cover install - 2" opening in the bottom



First design - with 1 Fan


Final design - 2 fans on both sides pull air all the time, i cannot hear them at all even during standby. 





PGXL installed behind my desk and I only rely on Windows PGXL application.
With latest FW release 3.4.10 Power reading is work properly and I do not have to see front panel of PGXL anymore...

Been on PGXL subject

2nd project - remote Power ON/OFF.
There are several ideas published - I purchased 30A Siemens relay on Amazon, put it to external enclose, connected it to WEMO switch and operate from Wemo application on my iPhone.

Here are few images
Wemo switch


Relay Box


Wemo application



My PGXL work properly on all Bands after initial High SWR issues and trip back to Flex in December. I am happy camper now.

While above project does not eliminate noise completely and would be pretty close to the noise that comes from Acom2000A that sit 2ft away from me. 
Also, characteristic of noise is different that Acom2000A (more higher pitch noise), but with above project I can work most the QSO's without headphones!

Enjoy
Sergey, KN7K

Doug

I am sure each operator has his/her level of tolerance on noise level. I am a new owner of the PGXL and must say the noise level at my station for my level of tolerance does not come close to requiring such measures. Each to his own but I think in fairness to Flex this might discourage sales of this amp which I feel is over reaching. Just MHO and every ones MMF.

Bill -VA3WTB

I was almost going to say the same thing. It seems that no matter how amazing this amp may be, with the high performance, Meffa and the harmonic filter and great build. all people talk about is the fan noise. But nice project Serg.

KF4HR

I just use noise canceling headphones.

Bob Needleman

I do not own a PGXL, but have owned other solid state HF amps in the past.  They are ALL noisy as compared to most modern tube amps, especially those using the small, high gain  metal/ceramic tetrodes/triodes (eg. 3CX800, 4CX800, 4CX1000, etc).  The issue is that the solid state amp designers must build in adequate cooling of the high power PA MOSFETS  to handle the stress of repeated heating/cooling down that occurs in amateur operation ( I understand that this is not an issue with commercial broadcast solid state transmitter/amp consoles that run continuously and are contained in full sized cabinetry with professionally designed ducted air or water-based cooling systems, etc). What you experience with all amateur solid state amps, especially operating CW or continuous duty modes is an initial low speed, fairly tolerable fan speed. But as you continue transmitting (eg. after 5 mins or so), the PA trannies will heat up to a critical temp and the heat sensing circuits will trigger the fan speed to go up to the next higher speed. This will continue to occur, with increasing fan speed as the PA temp increases. I don't know how loud the PGXL fan is on max. speed, but I do recall complaints about how noisy the Elecraft KPA1500 would get at max speed #7  (some owners likening it to the noise of a  '747 jet at takeoff!). WIth the current state of the art of solid state RF devices, there's really no way around fairly high dB level fans because the cabinetry is not large enough to build in a high capacity air flow system and  if the trannies are not kept cool, they will fail very quickly  and replacing them is an expensive undertaking. So before you buy a PGXL (or any other SS amp) take that into consideration. If all you do is rag chewing on SSB  speaking intermittently for a minute or two, you probably won't mind the fan. If you're doing 'old buzzard' long,drawn out AM transmissions, or contesting over long periods, either accept the fan noise, or remote the RF deck, because it is always going to be there (and that is a good thing to maximize the longevity of the amp).
Bob K3AC

Rick N4RZ

I commend Sergey on his efforts to make the amp work better for his situation!  His solution helps to mitigate the noise issue with this amp and gives one a method to turn the power off to the amp without having to access the rear panel which may be a problem for those whose access to the rear panel is not easy.  As for all, solid-state amps being noisy, my SPE 2K-FA is quieter than nearly all of the other amps I have owned recently most of which used tubes.