Topics

UBITX. FT8 heat sink requirements #ubitx #ft8

Praba Karan
 

What are heat sink requirements of ubitx for ft8 and other digital modes?. Just binding irf510 on back panel of casing(like in sunils case) is enough to withstand heavy duty cycle demanded by ft8?

Ghericoan
 

I am not using the irf510 in my ubitx, but rather the irf630. My heatsink is an old pentium 4 sink cut in half with both fets bolted to it through mica insulators and thermal grease.

On FT8 the heatsink does a wonderful job and only gets luke warm, even with back to back QSOs. However, on modes like WSPR, I had to attach a small fan or the sink would become too hot to touch.

But I am also pretty hard on my ubitx with running the PA on 36 volts and 1-1.4 amps. (I consider one amp of current to be running the PA wide open since I use a bias current of 160ma)

On Sun, Jun 3, 2018, 5:44 AM Praba Karan <vu3dxr@...> wrote:
What are heat sink requirements of ubitx for ft8 and other digital modes?. Just binding irf510 on back panel of casing(like in sunils case) is enough to withstand heavy duty cycle demanded by ft8?


--
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N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Ashhar Farhan
 

The ft8 has an overall cycle of 50%.i use it with the standard issue heatsink.
- f

On Sun, 3 Jun 2018, 16:07 Ghericoan, <boakawizkid@...> wrote:
I am not using the irf510 in my ubitx, but rather the irf630. My heatsink is an old pentium 4 sink cut in half with both fets bolted to it through mica insulators and thermal grease.

On FT8 the heatsink does a wonderful job and only gets luke warm, even with back to back QSOs. However, on modes like WSPR, I had to attach a small fan or the sink would become too hot to touch.

But I am also pretty hard on my ubitx with running the PA on 36 volts and 1-1.4 amps. (I consider one amp of current to be running the PA wide open since I use a bias current of 160ma)

On Sun, Jun 3, 2018, 5:44 AM Praba Karan <vu3dxr@...> wrote:
What are heat sink requirements of ubitx for ft8 and other digital modes?. Just binding irf510 on back panel of casing(like in sunils case) is enough to withstand heavy duty cycle demanded by ft8?

--
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N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Praba Karan
 

This means stock heat sink supplied is just enough for ft8?


On Sun, Jun 3, 2018, 4:30 PM Ashhar Farhan <farhanbox@...> wrote:
The ft8 has an overall cycle of 50%.i use it with the standard issue heatsink.
- f

On Sun, 3 Jun 2018, 16:07 Ghericoan, <boakawizkid@...> wrote:
I am not using the irf510 in my ubitx, but rather the irf630. My heatsink is an old pentium 4 sink cut in half with both fets bolted to it through mica insulators and thermal grease.

On FT8 the heatsink does a wonderful job and only gets luke warm, even with back to back QSOs. However, on modes like WSPR, I had to attach a small fan or the sink would become too hot to touch.

But I am also pretty hard on my ubitx with running the PA on 36 volts and 1-1.4 amps. (I consider one amp of current to be running the PA wide open since I use a bias current of 160ma)

On Sun, Jun 3, 2018, 5:44 AM Praba Karan <vu3dxr@...> wrote:
What are heat sink requirements of ubitx for ft8 and other digital modes?. Just binding irf510 on back panel of casing(like in sunils case) is enough to withstand heavy duty cycle demanded by ft8?

--
----------
N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Ashhar Farhan
 

Yes. 


On Sun, 3 Jun 2018, 17:38 Praba Karan, <vu3dxr@...> wrote:
This means stock heat sink supplied is just enough for ft8?

On Sun, Jun 3, 2018, 4:30 PM Ashhar Farhan <farhanbox@...> wrote:
The ft8 has an overall cycle of 50%.i use it with the standard issue heatsink.
- f

On Sun, 3 Jun 2018, 16:07 Ghericoan, <boakawizkid@...> wrote:
I am not using the irf510 in my ubitx, but rather the irf630. My heatsink is an old pentium 4 sink cut in half with both fets bolted to it through mica insulators and thermal grease.

On FT8 the heatsink does a wonderful job and only gets luke warm, even with back to back QSOs. However, on modes like WSPR, I had to attach a small fan or the sink would become too hot to touch.

But I am also pretty hard on my ubitx with running the PA on 36 volts and 1-1.4 amps. (I consider one amp of current to be running the PA wide open since I use a bias current of 160ma)

On Sun, Jun 3, 2018, 5:44 AM Praba Karan <vu3dxr@...> wrote:
What are heat sink requirements of ubitx for ft8 and other digital modes?. Just binding irf510 on back panel of casing(like in sunils case) is enough to withstand heavy duty cycle demanded by ft8?

--
----------
N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Bo Barry <bobarr@...>
 

FT8 does not have a heavy duty cycle. The other modes DO.
I have a small 5v fan with a dropping resistor to quieten it, and the long duty cycle WSPR works fine.

Ghericoan
 

Barry, just out of curiosity, what current and voltage do you run when doing WSPR?

I sit at around 36 volts at 1.4 amps, and the heatsink I use gets a bit too warm to touch unless I run the fan which brings noise into the receiver...

On Sun, Jun 3, 2018, 12:35 PM Bo Barry <bobarr@...> wrote:
FT8 does not have a heavy duty cycle. The other modes DO.
I have a small 5v fan with a dropping resistor to quieten it, and the long duty cycle WSPR works fine.


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N5WLF, Greggory (or my nickname, Ghericoan)
General Class, Digital Radio Hobbyist

Bo Barry <bobarr@...>
 

Hey 7 watts works the world on FT8 & WSPR. 😂. I'm using the stock model.
Bo W4GHV since '54

Tom Christian
 

Just to be safe, I mounted my irf510s (isolated) to the case.  In 2 months, I've had over 500 FT8 QSOs with no problems.
Tom
AB7WT

Arvo W0VRA
 

On Sun, Jun 3, 2018 at 09:44 am, Ghericoan wrote:
what current and voltage do you run when doing WSPR?
 
I don't want to become famous for this, but I accidentally ran a WSPR transmission on 40 M without the antenna connected.  My PS is 12V.  I don't know what the current draw is.  The heatsinks are stock with no fans.

The finals got very hot.  I do not recommend this procedure.  I did not have any reports for that transmission on the map.

The finals survived to transmit after they cooled off.

Bo Barry <bobarr@...>
 

I too don't note much heat on them but the little 3904s sure heat up. 
I did put one of the tiny Raspberry pi 5v fans with a dropping resistor to give them a little air. You have to add a 7805 regulator or hook onto the big on on the Raduino.
Bo W4GHV 

Don - KM4UDX
 

Greggory -- I'm using 24v for the finals, and doing WSPR 24/7 untill something glitches. I had to add bigger heatsinks and a fan.  This was the result of melting the 510 internals due to carelessness on my part...hahah. 

Anyway...my bias is at 110ma per side.  Does that seem appropriate for 24v?  What got you to 36v? What happens to your output power as you increased from 12v to 36v?

Thanks for any insight!!

Don

Aaron K5ATG
 

I'm guessing that the uBitx V6 transistors and heat sinks are good enough for the digital modes also?
--
'72
Aaron Scott
QRPARCI# 16443
GQRP# 16389
4SQRP # 1080

Mick
 

Aaron,
I run FT8 all the time without any over heat problems.
--
 

73
Mick VA3EPM 

Gordon Gibby
 

I doubt it seriously. Almost all Riggs, have to be Der ated a bit for continuous duty.   


On Jun 18, 2020, at 17:16, Mick <Mgsebele@...> wrote:

Aaron,
I run FT8 all the time without any over heat problems.
--
 

73
Mick VA3EPM 

Dean Souleles
 

Hey Don - I assume your transmit duty cycle on WSPR is still10-15% which means you transmit two minutes out of 20.

You should be able to run pretty much forever at that rate.

I've run  WSPR 24 hours multiple times with stock heat sinks,

Dean
KK4DAS

Gordon Gibby
 

yes for low duty cycle modes it should work


On Jun 18, 2020, at 21:10, Dean Souleles <dsouleles@...> wrote:

Hey Don - I assume your transmit duty cycle on WSPR is still10-15% which means you transmit two minutes out of 20.

You should be able to run pretty much forever at that rate.

I've run  WSPR 24 hours multiple times with stock heat sinks,

Dean
KK4DAS