HG WTF!

[Tallman]

That should make a 32 pill with them easy.....

As long as they are matched, you are correct. The first time I saw multiple FET's paralleled was on a TEKIN Electronic Speed Control for my RC10. They had 10 or 12 paralleled to replace the old wire wound resistor and servo driven wiper arm.
It was a lot smoother and more reliable.

 

[newoldguy]

ok well i am going to ask the question did you go thru the amp to be sure there wasn't something else going on ??? i am not that great at amps i am trying but to me there is a cause for every failure and you might be rite just low quality parts but did you check everything else out first ??

 

[Tokin]

ok well i am going to ask the question did you go thru the amp to be sure there wasn't something else going on ??? i am not that great at amps i am trying but to me there is a cause for every failure and you might be rite just low quality parts but did you check everything else out first ??

From the looks of the damage it appears to be poor manufacturing.
Im not a fan of Chinese knockoffs which is all the hg pills are. The Japanese took pride in their work and produced quality parts. China wants to steal others technology, copy it and mass produce lower quality parts. Knockoff look alike Toshiba red dots were available on DHgate for $50/pill or non red dots for 50/pair until last month. I see theyre gone now. I dont trust any pill amp to have correct/quality pills anymore unfortunately.

 

[Tokin]

Heres another china based seller who claims to have Toshiba 2879's for cheap, well cheap compared to what RF parts wants.

 

[Highway Man]

I'm guessing you guys saw the bbi tube video today about those fake pills.
yeah they may be fake but I'm hoping he puts them to the bench test because with the numbers he said they were doing and looking kin to Motorola it could be another option.

 

[loosecannon]

Shockwave already said it, but this is the part people need to start getting on board with:

https://www.rfparts.com/rd100hhf1.html

under 40 bucks, made for RF amplification, 12.5vdc operation.
its a winner.

can someone please just start making some 4 pill amplifier PC boards that will accommodate these, and temperature controlled bias.

whoever does that first is going to corner the amplifier market.
everyone will buy their PC boards for amp building from that person.
LC

 

[9C1Driver]

Wow, that has potential.

 

[Handy Andy]

Well then, refill your printer and get out the rulers (Metric types)

Here's the PDF....attached

Heres the link to the PDF thru Mitsubshi...

 

[Handy Andy]

If you look at the Dimensioning - they look almost like Drop in replacements for the W52K (4-leg Pill).

The "mounting flange" when you look at it - might mate up diagonally - to replace that which passed thru before...

Just (might) have to re-drill holes 90 degree (or 45?) offset to mate Gate - but it looks promising...

 

[Shadetree Mechanic]

Mounting it to the board is the easy part. My question is what to do for input and output transformers, and what reactance they need. Can we simply tack on some stuff to make it work or do we need a separate board for the biasing circuit. Can you tell that I don't know what I don't know? Haha!

 

[Handy Andy]

Well, the board can be scaled to meet dimensional character---note the scale parameters below the schematic and parts layout.

Because this part is scalable for different frequencies - just print the drawing and make up a PCB to match the test circuit jig- you should get similar results.

The "Gate" biasing issue is in the bypass, but again - looks pretty much straightforward to obtain Class AB if not high-class C operation - Heating aside - thermal biasing can be inserted past the 9.1K resistor in that C1 mess with up to three diodes to obtain a turn on characteristic. How - look for "hot gates" here in the forums - several chassis are doing similar designs using Tri-diode End to End to utilize the forward voltage drop to obtain a fixed voltage regulated by the thermal character of the diodes junctions.

 

[Highway Man]

oh just shoehorn a couple of those in a donkey stomper and see what happens

 

[blasphemy000]

Quite a few 100W HF rigs use the RD100HHF1 parts in their final sections. For ideas of how to properly set them up for Class-AB linear operation, you only need to look at the schematics of these radios. The Yaesu FT-450 and Kenwood TS-590S are two examples, but there are quite a few. Studying these proven designs can give you ideas for proper bias designs, negative feedback, input/output networks, ect. I doubt that it would take to much effort to mono-band the circuit. The test circuit in the datasheet is just to demonstrate how they obtained the specs listed in the datasheet. It doesn't show how the bias is setup or demonstrate any negative feedback to flatten out the input vs. output slope. I bought a couple of these for a homebrew HF rig I'm slowly building, but I'm nowhere close to needing the PA section yet, so they're still in the RFParts bag.
Now, being Mosfets, they probably won't take being overdriven like the bipolar devices do and the drive requirements are probably a bit lower. I'm sure they would make a great mono-band amplifier though, if built and driven properly, but I think people would just end up burning up the gates if they were used in a shootout type box.

 

[Shadetree Mechanic]

Might need some kind of active attenuator on the input to swamp the excess drive.

 

[Mudduckmobile]

From the looks of the damage it appears to be poor manufacturing.
Im not a fan of Chinese knockoffs which is all the hg pills are. The Japanese took pride in their work and produced quality parts. China wants to steal others technology, copy it and mass produce lower quality parts. Knockoff look alike Toshiba red dots were available on DHgate for $50/pill or non red dots for 50/pair until last month. I see theyre gone now. I dont trust any pill amp to have correct/quality pills anymore unfortunately.
View attachment 33586

here is a video that covers a lot of this.