4 SiC MOSFETs on 40 meters - hopefully by this weekend at Rattlesnake Island

[steve_qix]

Well, seeing as 40 meters has been pretty good, and 75 has been a bit anemic due to summer conditions, it's time to get on 40 from the shack at Rattlesnake Island.

So, I'm going to convert the 4 MOSFET SiC RF amplifier I tested on 75 over to 40 meters.  Need to cobble some type of cabinetry together, but hopefully I'll have this thing up and running from the island this weekend - we'll see!  Of course I still have to put up an antenna for 40, but I'm going to try a fan dipole (attach the 40 meter dipole to the existing 75/160 meter ant) and see how it goes.

Will post the results of tests and pics when the rig is up and running.  Should be interesting  to see how things work out up on 40 with these new MOSFETs.

[VE3ELQ]

Excellent Steve.  Be interesting to see how those big FETs work way up there.  LF to hearing the details.
Good luck es 73s  Nigel

[DMOD]

Hope to hear you on Fortee.

Phil - AC0OB

[steve_qix]

IT WORKS!!!

In fact, Phil AC0OB and Pete N1HCE were the first official contacts with the rig.

I was pulling too much current from the modulator during the first few transmissions, and this of course affected the audio (because the PWM filter was not properly terminated)... But, got that adjusted and everything sounded normal.

The heat sink stays amazingly cool for the power.

Really, so far it was fairly painless to get this 40 meter RF amp on the air.  Used parts lying around the shack for the output network, and an old chassis/front panel combination that my wife brought home from the dump at least 25 years - maybe 30 years ago.

Not the most beautiful thing in the world, but definitely passable.  Will take some pics when I get a chance.  Super simple - not much too it...

If I can get a working 40 meter antenna up at the island, we'll look for people over the long weekend.

Regards,  Steve

[DMOD]

You were 20-30 over S9 out here in the Middle of the Cornfield.

Once I widened the bandpass on the R-100A (QX Selectivity) it sounded excellent.

Phil - AC0OB

[VE3ELQ]

IT WORKS!!!


Regards,  Steve

Super job Steve. Another home run for the SiC family. 
Look for you on 40m
73s  Nigel

[John K5PRO]

FB for wife to bring a scrap panel with meters home from the dump for you. Good deal!

[WD5JKO]

FB for wife to bring a scrap panel with meters home from the dump for you. Good deal!

   I was thinking the same thing.....wow!

Jim
Wd5JKO

[w4bfs]

......  Used parts lying around the shack for the output network, and an old chassis/front panel combination that my wife brought home from the dump at least 25 years - maybe 30 years ago....

your wife rates a 10 on the understand-o-meter ..... do something nice for her

[steve_qix]

That was a long time ago    An event not likely to be repeated with Sherrie (who is very much of a minimalist and who also was not my wife at that time - but that's another story!!).

Oh these FETs are DRIVE HUNGRY, particularly on 40.  I had to increase the driver power supply voltage to 16V, and I may go up to 17V.

Putting the antenna up right now.  A fair amount of shack work to do before actually being able to transmit from here on the island, but antenna first!!

[W2PFY]

IT WORKS!!!

Great news Steve!Don't blow out that new pole pig

Opening the camp late this year. See you on the air around the 1st of June!!!

[W7SOE]

I am really enjoying following this.  Pictures of the 40m version?

Rich

[KA2DZT]

......  Used parts lying around the shack for the output network, and an old chassis/front panel combination that my wife brought home from the dump at least 25 years - maybe 30 years ago....

your wife rates a 10 on the understand-o-meter ..... do something nice for her

Buy her a xmtr to go with the meters

[steve_qix]

Sort of like all dressed up and no place to go!  Finally, I've got an antenna up, completely reconfigured the equipment including bringing up another rack (I just had a table rack for the existing transmitter), etc. etc...... and DARN!!  Forgot to bring an oscilloscope.  This is not normally a problem, but the first time you bring up a new class E rig, you HAVE to check all of the waveforms.  Although this 40 meter RF amplifier has been on the air, I'm using a different VFO, so the duty cycle has to be set for 40 meters.  Without a scope, I'm literally shooting in the dark.  My son is home, but home is 2 hours away, but Wayne WA1SSJ is much closer - hopefully I can borrow Wayne's scope - we'll see.  Otherwise, I guess I'll ask my son to meet me half way.

Oh well 

[KD0HUX]

Sort of like all dressed up and no place to go!  Finally, I've got an antenna up, completely reconfigured the equipment including bringing up another rack (I just had a table rack for the existing transmitter), etc. etc...... and DARN!!  Forgot to bring an oscilloscope.  This is not normally a problem, but the first time you bring up a new class E rig, you HAVE to check all of the waveforms.  Although this 40 meter RF amplifier has been on the air, I'm using a different VFO, so the duty cycle has to be set for 40 meters.  Without a scope, I'm literally shooting in the dark.  My son is home, but home is 2 hours away, but Wayne WA1SSJ is much closer - hopefully I can borrow Wayne's scope - we'll see.  Otherwise, I guess I'll ask my son to meet me half way.

Oh well 

Do not give up

[steve_qix]

Sort of like all dressed up and no place to go!  Finally, I've got an antenna up, completely reconfigured the equipment including bringing up another rack (I just had a table rack for the existing transmitter), etc. etc...... and DARN!!  Forgot to bring an oscilloscope.  This is not normally a problem, but the first time you bring up a new class E rig, you HAVE to check all of the waveforms.  Although this 40 meter RF amplifier has been on the air, I'm using a different VFO, so the duty cycle has to be set for 40 meters.  Without a scope, I'm literally shooting in the dark.  My son is home, but home is 2 hours away, but Wayne WA1SSJ is much closer - hopefully I can borrow Wayne's scope - we'll see.  Otherwise, I guess I'll ask my son to meet me half way.

Oh well 

Do not give up

Absolutely not !!! 

[W3GMS]

Sort of like all dressed up and no place to go!  Finally, I've got an antenna up, completely reconfigured the equipment including bringing up another rack (I just had a table rack for the existing transmitter), etc. etc...... and DARN!!  Forgot to bring an oscilloscope.  This is not normally a problem, but the first time you bring up a new class E rig, you HAVE to check all of the waveforms.  Although this 40 meter RF amplifier has been on the air, I'm using a different VFO, so the duty cycle has to be set for 40 meters.  Without a scope, I'm literally shooting in the dark.  My son is home, but home is 2 hours away, but Wayne WA1SSJ is much closer - hopefully I can borrow Wayne's scope - we'll see.  Otherwise, I guess I'll ask my son to meet me half way.

Oh well 

Turn that old analog TV into a scope 
   

[steve_qix]

Ok, Wayne WA1SSJ lent me his scope THANK YOU WAYNE!!

Got on the air with full power.... things worked well.  Will be on this evening (in a few minutes, actually).

Here are some pics.

This is the front with some components visible:



This is the inside.  The tank coil is in the foreground; tuning cap to the right; loading - back-center.  The power supply in the foreground-left is the 16.5 V supply for the drivers.


This is the overall big rig setup.  The 80/160 meter RF deck is on top;  Modulator/power supply in the middle, and the 40 meter RF deck in the lower rack.  The power transformer and some other components can also be seen in the lower rack.



The station at Rattlesnake Island with the 40 meter rig integrated with the other equipment:

[N2DTS]

I only had a very short time to listen, and tuned you in as you were trying to sign out, but heard you well in South Jersey.
Sounded fine, was quite wide by 40 meter standards, my sdr-iq had you 7285 to 7305 or there abouts, but I did not have time to study it.
I was down frequency and when you started transmitting and heard a burst of noise and then tuned up and listened to you.
You might have someone listen 7 or 10 Kc  when you start transmitting to make sure nothing odd is happening.

Sounded fine on frequency though.

[N8SDR]

Talked with Steve briefly this evening, as storms and static crashes about the area.

Attached is a audio clip of the 4 sic Mosfet 40 meter rig.

sounding good here Steve, too bad the static and crashes were around..


N8SDR

[steve_qix]

Thanks for the recording!  There was a lot of static around, that's for sure.  I could see lightning from a storm about 30 miles away looking West from the island, overlooking the lake.  That storm just missed us and went off to the North.  But the static, as you can imagine, was terrific.  Still, I was hearing you quite well !  I brought the 40 meter RF amplifier home with me - still needs work.