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Reviews For: PAE-Kx31 KX3 Heatsink

Category: QRP Accessories

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Review Summary For : PAE-Kx31 KX3 Heatsink
Reviews: 19MSRP: 89.95
The PAE-Kx31 gives the Elecraft™ KX3 up to 400% longer key-down transmit time than stock (band dependent) when cooled by natural convection. It is a billet-aluminum piece black-anodized to compliment the appearance of the rig. It is designed for the majority of operators and will allow for greatly extended transmit time in any digital mode or band at the full 10W output. It incorporates several features not found on competing heatsinks:

Designed using thermal modeling software for best performance.
Ratio of base mass to fin area optimized for the duty cycle of digital modes.
Rounded cross-section for no-snag use in fabric cases, and no sharp corners to cut or damage adjacent objects (including humans!).
When mounted on Elecraft™ KX3 along with GemsProducts™ SideKX plates and cover, the combo will fit in a standard Rose’s KX3 case.
Custom-color black anodized instead of powder-coated for superior thermal performance.
Radiusing compliments the design of the Elecraft™ KX3 and the GemsProducts™ SideKX.
It’s design interlocks with and greatly enhances the impact resistance of the SideKX Cover.
Low profile at each end for an interference-free fit with the PAE-Kx35 Mobile Mount (in beta testing).
Optimum compromise for most all operators between stock appearance and enhanced transmit time.
The Kx31 is supplied with correct longer replacement black-oxide stainless steel screws and a packet of heat-transfer grease.
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
KD2JNF Rating: 2016-03-10
Great product Time Owned: N.A.
When I started to use the KX3 in JT65 mode it would rarely let me reach 10W for a few sessions. The rig would reach 60C degrees in fall back to 5 watts.

So after reading a few positive comments on PAE KX3 heatsink I decided to buy the product.
It turned out to be the right decision and the product is worth every penny.

Then Elecraft released a firmware update allowing the KX3 to run at 15W maximum. The PAE heatsink could not keep up with this power level. But I found a good and cheap solution. I placed a small 12V CPU fan on top of the heatsink in the area where the two screws connecting the output transistor are. That did the trick. I can now safely run JT65 mode for hours without overheating the radio. The temperature rarely goes over 52C.
Since the fan runs on 12v I use a Y adapter to power it from the same source as the KX3.
By the way, I installed the PAE heatsink dry, without using the supplied "cream".

So all in all a good product and I highly recommend it.

VA7BC Rating: 2015-06-06
The best Time Owned: more than 12 months.
Looked at all different heatsink options for the KX3. The specifications and manufacturing on this heat sink are what sold me. When I received it I noted build quality was superb. Have had it now for just over 1 year and it works very well. No regrets.
WA8EBM Rating: 2015-02-06
Better than anticipated Time Owned: 0 to 3 months.
Just got my almost 3 yr old KX3 back from Elecraft-of all things failure due to tin whiskers growing on the flex cable connector between the halves. I had installed the heatsink earlier by simply replacing it with the stock one and now re-installed it by removing the powder coat and using the heat sink compound. Just tested key down and went 2 minutes at 10 watts and it reached 48C it then took 30 seconds to return down to 30C. I now have no qualms, when the weather permits, to operate portable at full power on JT65 with my AlexLoop.
A superbly crafted product with an essential anodized vs painted coating.
WU6X Rating: 2014-11-07
Enhanced DATA Modes Performance Time Owned: 0 to 3 months.
Before the ProAudio Engineering heat sink addition to my KX3, key-down PSK testing at 3 watts into 50 ohm load quickly brought the radio to 51 deg C, hot to the touch and close to shutdown. After adding the heat sink, key-down PSK into a 50 ohm load at "10 watts" got the PA.I temp to only 43 deg C and it was still going strong ... at twice the power out with no thermal issues. This is a must have, quality after-market product for the KX3 if you want to work data modes at more than 3 watts. Build quality matches the quality of the radio.

Three install options are available: 1) remove the old heatsink and install the new one; 2) add heat sink compound during installation; 3) remove paint at contact area. AND add heat sink compound. I opted for Option #3 for maximum heat transfer, removing the external paint on a small patch around the transistor mounting area (masking the area and using paint remover) and then adding heat sink compound (included) to both the transistors and the PAE heat sink before mounting. Excellent install instructions ... excellent product, it looks "factory" and it works!
OE9FWV Rating: 2014-09-10
very good construction Time Owned: 0 to 3 months.
I installed the heatsink today, instructions are detailed, there are 3 options to choose (I chose option 1 without removing paint from the KX3 housing) The heatsink adds little to the size of the KX3, it has rounded fins looks good and improves cooling of the finals.
W9AC Rating: 2014-08-22
Well designed Time Owned: 0 to 3 months.
Excellent CNC machining and PAE's version of the KX3 heat-sink uses the proper black-anodized surface treatment for maximum thermal emissivity. The instruction set is clear and allows the owner to choose one of several mounting methods.

WA5PQL Rating: 2014-08-22
First Class Product Time Owned: 0 to 3 months.
The heat sink was very easy to install. (Used method no. 3) I can now transmit full power using my KX3 in PSK mode and hold long QSO's without overheating. This product is a must-have for KX3 owners.
ON4VP Rating: 2014-08-21
Turns my KX3 into a workhorse Time Owned: 0 to 3 months.
I think the Elecraft KX3 is a nice little radio that has a lot of potential but no radio is perfect and also the KX3 has its flaws. To me one of them is the heat building up when doing CW or digital modes and trying to use the 10 watts output.

While for normal ssb operation most KX3 owners will never experience power cut off, when making digital mode or CW qso's the finals of the KX3 rapidly warm up to a point where the radio cuts back the power to 5 watts or even stops transmitting.

The PAE-Kx31 KX3 heatsinc is a nice design that accommodates the KX3 just fine. The rounded shapes at the corners and the finish of the product are of high quality and make the KX3 looks great. The thermal performance can be up to almost 4 times that of the original design depending on which of the 3 provided approaches you will choose to install the heatsinc.

The heatsinc is well packed for transport and included are a nice documentation, all the screws and thermal paste to finish the build.

Once the heatsinc was in place I noticed a large improvement of dissipated heat and running the KX3 in WSPR for tx periods of two minutes every time the PA temperature never surpassed the 37°C. That's pretty impressive while originally I came close to 55°C at almost the cut off temp of 60°.

I now feel very confident in using the KX3 for digital modes and more intensive CW use.

Although the price is a bit steep and for us Europeans we also have to add some import taxes, I still believe the added value is great considering the quality of the product and the performance improvement. Time between order and delivery was about 3 weeks including custom clearance. Good email response from the seller.

I recommend this product.
W8OQ Rating: 2014-07-13
Works Well Time Owned: 0 to 3 months.
This heatsink is very well designed and the manufacturing quality is excellent. I used installation method #3 which required removing the RF circuit board and scraping the black coating from inside the back panel - a fairly easy procedure. I like to use QRP RTTY with the KX3 and it has never reached the temperature limit with this heatsink. The KX3 also has a reputation for frequency drift while using some of the digimodes such as PSK, JT65 and WSPR. I am hoping that the smaller temperature rise will alleviate some of the drift. The installed heatsink looks like OEM. Good product.
PA3BWK Rating: 2014-06-24
Exeeds spec's Time Owned: 0 to 3 months.
Altough I love my KX3 the lack of cooling is annoying when you want to operate full power in CW for instance.
First I opted to buy the German qrpprojects heatsink for less money.
Bummer, that was slightly better but did not met my expectations. Although it is not cheap I decided to go for the PAE-Kx31 heatsink.
It was promptly delivered, very well packed and documentated. The heatsink itself is A-Grade in quality and finish AND performance.
My advice is to go for option 3 to install this heatsink, that is not the easiest option but not difficult for us ham's.
It will ensure you the maximum performance.
After installing I conducted my own test. I can assure you that the PA unit of the KX3 is well designed too....I decided to put the brick on the key. It took almost 20 minutes to go from room temperature 21C to 60C....
IMHO it changed the character and use of this transceiver.
Hopefully Elecraft will incorporate this in their design or at least sell this as an option for their KX3 range.
This is a 'must have' for all KX3 owners!