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[KT0DD]

Just tried clicking on a few links on Tom's site but they don't seem to work. I was thinking about ordering update parts for my 09/ 2007 AL811H amp I inherited. I see they no longer repair amplifiers so, I am wondering if they do anything for Ham Radio anymore? Thanks.

Todd - KT0DD

[W1QJ]

Yes, Tom is selling preassembled kits of parts to upgrades the various Ameritron amps.  He’s got universal products that can adapt to other amps as well.  He’s got an ordering page for products.   Ameritron has made many bad changes to some amps and Tom has been figuring out the fixes.  The worst product they messed up is all the solid state amps.  Best to totally stay away from them all.

[VE7RF]

Just tried clicking on a few links on Tom's site but they don't seem to work. I was thinking about ordering update parts for my 09/ 2007 AL811H amp I inherited. I see they no longer repair amplifiers so, I am wondering if they do anything for Ham Radio anymore? Thanks.

Todd - KT0DD

Links work just fine..as of 5 secs ago.
https://www.ctrengineeringinc.com/
Click on "MENU"  at left side of blue bar.

scroll 1/2 way down, till u get to.... 'ameritron al-811 . 811h upgrade kits'

U end up here....  https://www.ctrengineeringinc.com/ameritron-811-8https-www-ctrengineeringinc-com-shared-files-651-upgrade-kit-al811-and-al811h-amplifier-5final-1-pdf11h-upgrade-kits/

if u really want to do it right, replace the 811's with 572B's.   Also take heed of his fan upgrade. Oem chinese fan only provides 30% of required airflow.

[KT0DD]

Thanks for the link. I restarted my PC and now the link works. Time for a new PC. This one is 10yrs old.

Todd-KT0DD

[KA4KOE]

Tom is literally swamped with repairs to Ameritron solid state amps.

https://www.ctrengineeringinc.com/welcome-to-ctr-engineering-inc/ameritron-and-other-amplifier-repair-service/

[AI5BC]

Tom is literally swamped with repairs to Ameritron solid state amps.

Sounds like a Chevy Vega or Ford Pinto, always in the shop or chariots of fire.

[AC2RY]

Tom is literally swamped with repairs to Ameritron solid state amps.

Sounds like a Chevy Vega or Ford Pinto, always in the shop or chariots of fire.

And HAM public still buy them regardless.

[AI5BC]

Sounds like a Chevy Vega or Ford Pinto, always in the shop or chariots of fire.

And HAM public still buy them regardless.

Yep, same magic happens when you go to Lost Wages NV. You go there, get cheated and robbed in every joint, go home tell all your friends all about it, and you cannot wait to go back.

[VE7RF]

Tom is literally swamped with repairs to Ameritron solid state amps.

https://www.ctrengineeringinc.com/welcome-to-ctr-engineering-inc/ameritron-and-other-amplifier-repair-service/

After Tom left Ameritron in 2019, whatever quality left, went out the window.  On his Ameritron FB group, he sez the quality of the Ameritron SS amps is beyond piss poor.  Primary failures are devices not attached properly to the mating heatsink.  He sez he spends 8 hrs repairing just one SS amp, loses money on every one of em, and repairs include  wetsanding everything to a mirror finish, replacing devices,  and using the correct type, and amount of heatsink goop.   Tom sez some of the units that came in would handle 300w ccs, some 400w, some 500w, it's all over the map.  He also showed pix of the ameritron..'repair' jobs..which was done badly.  Owners gave up, then sent the 'repaired' unit to Tom, for the correct repair.

Other issues were ameritrons changing the sequence of the LP filters.  The highest freqs should be the furthest away from the  main input, same as my AS remote switch box. Otherwise,  you end up with a stub effect, due to the myriad of relays used to switch the myriad of LP filters.  You can't avoid the stub effect, so the lowest freqs go closest to the input.    I know one fellow who's AL-600 blew up in < 1 min, brand new,  ditto with the replacement.   3rd unit was fine.  The 1st 2 x units, the devices were not even touching the heatsinks, wtf?

One fellow on the amp forum, had a contract with one of the HRO's (this was years ago).   His job was to unbox, and test each ameritron tube amp, before HRO shipped it to the customer.  He ended up  taking them all apart BEFORE  plugging them in.  Typ issues were stuff not soldered, tank coils leaning over, and ready to short out, HV lytics installed backwards, eq resistors across hv caps missing, or not soldered, or gone open.. you name it.  'Simpler'  to find and fix all those issues 1st...THEN plug it in and test it.   Otherwise if you just test it 1st, stuff blows up. 

There is no way in hell their amplifiers are tested before they leave the factory, not a chance.  No  QC stickers on em.  For all the hassle, and shipping all over the map, repairing, shipping back etc,  it woulda been cheaper to just  test each unit before it left the factory.

Below is from Tom's site.

"Ameritron (and other) Amplifier Repair Service.
Until further notice, we have decided to halt all intake of amateur amplifiers. A large part of this decision centers around construction inconsistencies in Ameritron amplifiers, the time it takes to find random incorrect parts, and the time and risk involved in correcting component and workmanship errors.)

[W1VT]

https://www.nxp.com/files-static/rf_if/doc/app_note/AN1040.pdf
This document suggests that a mirror finish may be excessive for a heat sink.

[AC2RY]

https://www.nxp.com/files-static/rf_if/doc/app_note/AN1040.pdf
This document suggests that a mirror finish may be excessive for a heat sink.

You do not need polished surface. You may have polished, but still non-flat surface and this will not work. What you need is a FLAT surface. Any roughness will be solved by compound used between transistors and heatsink. But the compound will not help if heatsink surface is not flat.

[W9IQ]

As you increase the power dissipation requirements for the device, the quality of the surface finish becomes more critical. In this application, spotfacing of the heatsink is a requirement. A 0.4 μm Ra finish is not out of the question.

Thermal compounds are a compromise - not a solution - for rough surface finishes. The thermal resistance the compound is always greater than the base metal.

- Glenn W9IQ

[VE7RF]

As you increase the power dissipation requirements for the device, the quality of the surface finish becomes more critical. In this application, spotfacing of the heatsink is a requirement. A 0.4 μm Ra finish is not out of the question.

Thermal compounds are a compromise - not a solution - for rough surface finishes. The thermal resistance the compound is always greater than the base metal.

- Glenn W9IQ

Agreed.  Trying to extract stupid amounts of heat from a relatively puny LDMOS device  is sketchy at best, but doable. At 3.41 BTU's per watt...that's a lotta BTU's to extract....and ultimately dump to the surrounding air.

[W1VT]

I bought and learned how to use a miniature Sherline milling machine to make flat surfaces for RF power transistor attachment.
I also obtained high helix tooling for working with aluminum.  It is just the right size for working with electronic projects.

From what I've read 3D printing isn't anywhere close to meeting the requirements for a custom heat sink.

Zak W1VT

[VE7RF]

When applying the thermal compound, don't pile it on thick.  Spread it on as evenly as you can.  Then use either a razor blade, or credit card, and use just a single stroke to even it all out. What remains is a thin, uniform thickness, layer of thermal compound.

I don't install LDMOS, but do use those arcol, metal finned power resistors from 25 watts  up to 300 watts.   The 300 watt versions are small things, that bolt to the heatsink / chassis  with 6 x  1/4-20 SS bolts.   The little 25 watt types just use 2 x machine screws, (4-40 or 6-32)  diagonal to each other.