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 91 
 on: April 24, 2017, 08:45:51 PM 
Started by W1TAV - Last post by flintstone mop
A lot of hard labor in your radio room
Al, nice job

 92 
 on: April 24, 2017, 07:47:51 PM 
Started by w8khk - Last post by KD6VXI
I only use sil pads now.  Unless it's something I have a mica insulator for.

AFAIK, sil pads do NOT use any heat sink compound.  I've never used any, fwiw.

My CNC controller has the same types of sinks on each channel (I have a 4 axis control).  Each ic has a sil pad that had adhesive on both sides.

Remove adhesive, apply to ic.  Remove adhesive on top, apply heat sink to the chip.

--Shane
KD6VXI

 93 
 on: April 24, 2017, 06:33:46 PM 
Started by VE3ELQ - Last post by W3GMS
So great to work you on 3.705 with your new rig Nigel.   It sounded fantastic! 

73,
Joe-W3GMS 

 94 
 on: April 24, 2017, 05:29:58 PM 
Started by w8khk - Last post by w8khk
Thanks, Jim.  I am planning to use sixteen FQA11N90 fets.  I believe they are similar to the TO220 tabs, albeit a bit larger.  Wondering if you would use sil-pads, or would mica be better?

I am not up on the various heat sink compound qualities.  I bought a small tub of HALNZIYE HY400 thermal grease, wondering if that is any good for this application, and whether I should use it with mica, or with sil-pads, or just sil-pads.

I am open to other suggestions and do not mind spending a bit more to protect my investment thus far.   I will be using the overload/shutdown circuits and protecting the rig as much as possible....

 95 
 on: April 24, 2017, 05:14:45 PM 
Started by w8khk - Last post by WD5JKO

Rick,

    This thermal stuff is full of pitfalls. The K7DYY SS Class D rig uses plastic insulated FET's so they don't need an insulator. The compromise there is the convenience of not having an insulator is replaced with a much higher thermal impedance junction to heatsink.

     Then there are some GAN FET's and possibly some SIC Fet's which make the FET case the source instead of the drain. They should all be made that way!

      The TO-220 package is subject to mechanical cocking from the screw tightening, so the area getting hot might not be clamped very well. The insulator can get pinched too from this effect on the tab side.

      Then the thermal greases made are NOT the same. Most are now ROHS compliant, and therefore pretty useless, but still better than air.

      Jim
Wd5JKO

 96 
 on: April 24, 2017, 03:31:29 PM 
Started by AG5CK - Last post by KA2DZT
Thanks for the input. I will do some more testing when I get a chance and see what I can find. After looking at an old Amertran brochure I found here I believe it has split windings on the secondary. With the jumper removed the sec voltage is lower than the primary. I suppose that could also be a sign of a burned winding.

Im going to have to pull some strings on the oven. Mine is electric.

If you remove the jumper and still connect to 5 and 12 you only have the volt meter on two open windings.  Put the volt meter to 5 or 12 and then read voltage off the taps  5 with a tap and then 12 and the other set of taps. 

First thing to do is remove all power and do some ohmmeter testing.  Let us know what you find.

 97 
 on: April 24, 2017, 03:19:46 PM 
Started by W3GMS - Last post by W3GMS

Yes, the word definitely needs to get out.  This year we are listed in ER, CQ and QST!  

Joe-W3GMS  
Joe and Martha will see to it that word does get out going forward.  They have graciously offered to work with us and I have bestowed the title of "Benevolent Dictator's Executive Committee" on them.

Thanks to Joe's efforts the League has seen the light and come to Jesus.  We will now be listed on both their Web site and in QST.

I thank them for joining the team to make NEAR-Fest even better than it already is.

73,

MisterMike, W1RC
Benevolent Dictator





 Smiley !

Joe-GMS

 98 
 on: April 24, 2017, 03:16:51 PM 
Started by AG5CK - Last post by AG5CK
Thanks for the input. I will do some more testing when I get a chance and see what I can find. After looking at an old Amertran brochure I found here I believe it has split windings on the secondary. With the jumper removed the sec voltage is lower than the primary. I suppose that could also be a sign of a burned winding.

Im going to have to pull some strings on the oven. Mine is electric.

 99 
 on: April 24, 2017, 02:03:46 PM 
Started by W2PHL - Last post by W2PHL
 With the DDS VFO and the ebay amp transmitting on 3.875 MHz, 7.75MHz is 35dB down and 11.625MHz is 8dB down. Running that combo through the AL-1500, 7.75 MHz is 44 dB down and 11.625 MHz is 54 dB down.

 100 
 on: April 24, 2017, 11:23:54 AM 
Started by WBear2GCR - Last post by flintstone mop
ahhhh such a shame..Usually hard to kill those things; but glass is fragile

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