Been working some CW and V6 seems to be running a lot warmer than it did on SSB and I ran FT8 but didn't notice the cas getting as warm as it was now.
could the finals be going.
What check looked at is there test points to look at?
Chuck

Hi Chuck,

I doubt you have smoked anything if it is still trying to work (did I miss something?). I would expect a difference in 'feels like' temperature at the finals heat sink just from changing the mode between SSB and CW. The duty cycles are different and could easily be less on SSB voice. The finals WILL get warm. Installing a larger heat sink might make that a little less warm but by fingertip you might not be able to tell.

You are suggesting that you may not have the bias set correctly. In the past I have worked on some of these for other hams, setting up the bias, calibrating, and setting the BFO. They sent me the radio, I did the work, sent it back working. They didn't learn much more than my mailing address. I am still willing to do that mail thing..

???? *BUT*

It might be more helpful to use something like facetime (Apple) or Zoom etc, to try and help. Would you accept an offer of that kind of help? You would be able to learn a lot more than my mailing address. It will require more effort than using USPS as described above but seems like it would be worthwhile.

What do you have for test/measurement gear? If you want me to try this (or not) we should move this to private email. If you can't sort my email address from the list defaults? it is:

wrcromwell@...

73,

Bill? KU8H

bark less - wag more

Chuck

Reminds me of discovering the hot regulator on the arguing board thinking I had damaged it.?

As Bill suggests, 15 seconds of ft8 twice a minute is more punishing than cw or ssb. While some may adopt bigger heating, a little fan would help. Funny thing these transistors are robust, over voltage from very bad swr might get them before heat.?

73 Curt

Doesn't FT8 depend on your audio level settings?

A small 1inch fan might be all you need. You can slow it down to a point where it doesn't makes irritating noise since all you need is a slight breeze not a hurricane.?

On Sat, Apr 24, 2021 at 10:17 AM, Mark - N7EKU wrote:

Doesn't FT8 depend on your audio level settings?

Mark,
You are correct.??

Chuck,
Do you have a power meter to see if there is a significant power difference?? That could help explain what is happening.? If nothing else measure the peak voltage on the dummy load.? We are only looking for relative readings, not accurate.

The other variable is how long are you holding the key down when testing CW.

73
Evan
AC9TU

开云体育

A 1 inch fan wouldn't move much air.? Try something a little bigger.

73

VE4GKS

Sent by the Thunderbird

A one inch fan moves enough air over those heat sinks, anything bigger is a waste as the air just bypasses the sinks.At work, we cool a lot more than those puny heat sinks with one 1 inch fan . There isn't that much heat to be removed. If one is really that concerned especially for digital modes replace the transistors with one that can be directly grounded and use a heat sink / copper spreader arrangement. I don't like using insulators under those transistors since if the heat sink is grounded you end up with added capacitance that will reduce the output power at the higher frequencies even more.

I imagine there are numerous ubitx with fans pictured on the web - so go on a tour!? Thermal science of transistors is a bit abstract even working with PhDs I work with - so stay with your conviction on how much air you want to move.? I haven't yet down FT8 with my ubitx - but it tends to be shoot with what you have mode - I imagine big stations may be running hundreds of watts - but certainly QSOs can be had with a stock ubitx.? The fans in my switching power supply scream a bit - possibly you might want a switch to turn it off when doing CW and SSB - your call its your custom ubitx.?

73 Curt

On Sat, Apr 24, 2021 at 08:32 PM, Curt wrote:

I imagine there are numerous ubitx with fans pictured on the web - so go on a tour!?

Ahh yes, the ole just because others have done it, it must always be correct. Because people have always used parts outside their design specifications we will have to do that in all eternity.? The hobby is full with those statements .I sometimes wonder how humanity ever was been able to leave caves and evolve lol.

Ok got together with Bill KU8H on iPhone FaceTime and at 386 mile away he helped me do the adjustments and check voltage. The radio seems to be working as it should have seen the relay stick a few times. But I been able to make a few contacts I worked Army MARS station at Annapolis this past weekend on 60M.?

Bill was a big help and I appreciated him taking time to help me. He was very patient with me.
just wanted to update you guys.
Oh I picked up a small desk fan at the Dollar Tree it runs on a AAA battery. I just lay fan on top the vent holes on the top case and the air circulates around the finals and heat sink.No interference and it helps keep the finals cool but I have only been operating SSB and CW.?
Thanks again for all the help and Bill a big thats
73?
Chuck KA3DFK?