Improving cooling of JUMA PA100-D

[HB9VQQ]

Greetings,

I am using my PA100-D mainly for digi modes. SWR is below 1.5, still PA gets hot (70 degrees celsius) when operating in digi modes like RTTY , Olivia, JT65 etc. Usually running max.50W
Is there an easy modification to improve cooling of the PA ? Replacing heatsink or bigger Fan ?

73
Roland

[OH7SV]

Roland,

You are right that digi modes load more and especially if the 'keydown' transmit period is long the temperature will increase. Good news is that we have not heard any PA transistor failures in JUMA PA100-D.

There is one very easy improvement for additional cooling. See the section 3. in the "JUMA PA100 Recommended Modifications" in this link http://www.jumaradio.com/juma-pa100/JUM ... tions.html

Another option to improve cooling is to change the fan with a more efficient one. The original fan specs is 12VDC, 1.1W, size 50mm x 50mm x 10mm, Mounting holes 40 x 40 mm. You can consider a mechanically compatible 1.5W-3W 12V fan.

73 Matti OH7SV

[HB9VQQ]

Hi Matti,

thanks for your reply. Seems that is already the case with my PA100-D.



Happy New Year !
73 Roland

[HB9VQQ]

I just ordered a replacement FAN http://bit.ly/2EzeSin see how this works.
According to spec sheet this FAN provides 15,1m3/h airflow while consuming only 0.6W.

The original FAN in my PA100-D is from Yen Sun Technology Model FD5010-N (12V, 0.09A)

providing 10.9 CFM which equals to 18.5 m3/h... hmmm maybe ordered too quick...

Roland

[HB9VQQ]

Hi Matti,

I replaced the stock Fan with a Noiseblocker NB-BlacksilentPRO PR2 ( 60x60x25mm ) http://bit.ly/2AvrRyg. It is bigger than the stock Fan (50x50x10mm) but with the help uf some Sugru I fixed the new Fan to the Fins of the Heatsink. The Noiseblocker delivers an airflow of 29m3/h and is super quiet (19.9dBA at full speed).







Now I let the Sugru dry for a total of 24hrs, before testing and comparing the thermal results with the Stock Fan.

73
Roland

[OH7SV]

Ok Roland,

Please check that the fan is blowing towards the heatsink! (Not sucking)
How was the original fan installed?

73 Matti OH7SV

[HB9VQQ]

Well the stock fan was installed pointing the arrow on the housing of the Fan outwards, NOT blowing to the heatsink .... So I installed the new Fan the same way...

[OH7SV]

Roland,

Oh... that explains why you got so high temperature readings.
You can consider to install the original fan into the correct orientation.

73 Matti OH7SV

[HB9VQQ]

Hmmm that is a very good point. Purchased my PA100-D second hand, never questioned the install of the Fan... Since I already installed the new Fan blowing outwards and out of curiosity I will measure the thermal impact compared to blowing to the heatsink.

Stay tuned
73

[HB9VQQ]

Did some more Fan testing today. Here is the link to the spreadsheet with the measurements

https://docs.google.com/spreadsheets/d/ ... sp=sharing

While the stock Fan seems to be the most efficient in terms of cooling, I still prefer the Noiseblocker NB-BlacksilentPRO PR2 (60x60) because it is only less efficient by a small margin and because it is so super quiet in comparison to the stock Fan. And yes the airflow direction makes a difference Thanks Matti

73
Roland