Hg 2879c

[Shockwave]

This last batch I bought. Was fixing a straight 6 pill/ transistor amplifier. Set up as 2 device sections. Had to match every capacitor ( all inputs within 1 of, all capacitors across transformers within 2pf, capacitors from collector to ground all matched within 1pf and same for outputs) so no imbalance, all new matched transformers ( yes I had to do 2 or 3 wraps on each and check inductance to make sure right material and all very close, within 0.1uH of each other) All new transistors matched. Still have an imbalance. Even though they should all be the same. I tested each 2 device section individually. Bypassing relay and 3 port splitter/ combiners. Each one did different output, vswr on input all different. The regular HG are garbage. I will never use again. The C’s are better. But not a lot.

So much for spending the extra money on "matched" HG transistors. Did you happen to test the hfe of them before installation to see if they were even close on DC gain? Not that this will tell you how they respond at RF, but it would be interesting to see if they are even making any effort to match at DC. If you can't see a difference at DC, start checking the base to emitter capacitance and the collector to emitter capacitance. This will likely reveal why the input and output impedances are different at RF. You can probably do a better job of matching them, than what you paid for.

My mind is still shocked that no one has cracked open the back of a modern mobile HF rig and started cloning the two transistor RD100HFF1 output stage, as opposed to struggling with these parts that are simply not as advertised. If I still had a 12 volt "customer base", this would have been the very first thing to do. Imagine the advantage you would have, using the latest and most advanced RF output MOSFET's, in the 12 volt class? While not the way to go for base use, until our vehicles start using 48 volt electrical systems, the RD100HFF1 is the only HF, 12 volt, 100 watt, linear RF transistor in production today, that is worth working with.

 

[Crusher]

These were matched by curve tracer, marked 63, I used Sencore TF46 and did check hfe. I went through 18 to find 6 that tested 41 & 42. Yes I used power device setting not small signal setting.

I have built a few 2 device using the rd100fhh1 device. I like it. But still not really for a CB’er. As more drive is better mentality will kill them too. One I have now I still have a little more to do as it’s showing a oscillation on the spectrum analyzer. Think I need more DC filtering.

 

[flush]

I have new real 2879As. How do I sell them since there's so many fakes out there.

 

[Dr_DX]

According to several repair shops the "16D08" version of the HG 2SC2879 is the closest thing to a drop in replacement for a real Toshiba. The HG 2SC2879C is a different animal.

https://www.ebay.com/itm/162116182904?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649

 

[Tokin]

Thats a BBI quote lol.
HG is all there is and most builders are making them work, texas star being the only exception i know of who are using supposed dei which i believe are restamped older versions of hg's. I wouldnt be surprised if the famous 6-j toshiba fakes are an older restamped hg version.
I dont hear of users bitching about C's or the 16d08 as long as swr, drive and volts are kept to moderate levels. FatBoy is selling a lot of hg amps as is carl built, hopper and others. Rooster radio on yt has been getting monthly shipments from fatboy and selling out. The last i saw was a 16 pill 2879C amp 400 amp regulated supply combo ( ) and a crap load of 4 and 8 pill amps. Give it a year and see how many of these amps have issues. Till then ill keep buying toshiba amps that come up for sale locally. Lots of older operators
Gatekeeper still has my dx1600 rebuild with 2879C's in line to be worked on. Im interested to see how it performs. Thanks to some radio family ive got a couple good toshiba amps to run till I get the hg.

 

[Dmans]

Tokin,
Good to see you back on the Forum. Don't stay gone so long next time!

73
David

 

[S&W357]

Yep

 

[Dr_DX]

Thats a BBI quote lol.
HG is all there is and most builders are making them work, texas star being the only exception i know of who are using supposed dei which i believe are restamped older versions of hg's. I wouldnt be surprised if the famous 6-j toshiba fakes are an older restamped hg version.
I dont hear of users bitching about C's or the 16d08 as long as swr, drive and volts are kept to moderate levels. FatBoy is selling a lot of hg amps as is carl built, hopper and others. Rooster radio on yt has been getting monthly shipments from fatboy and selling out. The last i saw was a 16 pill 2879C amp 400 amp regulated supply combo ( ) and a crap load of 4 and 8 pill amps. Give it a year and see how many of these amps have issues. Till then ill keep buying toshiba amps that come up for sale locally. Lots of older operators
Gatekeeper still has my dx1600 rebuild with 2879C's in line to be worked on. Im interested to see how it performs. Thanks to some radio family ive got a couple good toshiba amps to run till I get the hg.

Apples and Oranges.

BBI did state that in a video but it wasn't just him. I have talked with other repair shops and that is their opinion as well. The OP was trying to find out what had to be changed to use HG 2879C's in an original Toshiba box. My post was referring to the closest transistor to a "drop in replacement" with NO input and output impedance adjustments in an original Toshiba box was the HG 16D08 version. I still stand by that statement, as do a bunch of repair shops (not builders).

You are talking about new builds that were never a Toshiba box and where the builder has changed the impedances (from a Toshiba box) to better match the device used.

That's not what this thread is about.

 

[Ranch55]

I wouldnt be surprised if the famous 6-j toshiba fakes are an older restamped hg version.

Those 6-J Toshiba knockoffs are definitely NOT restamped HG's .....
I have popped the top off of one and compared to a HG, very different construction internally.
The 6-J knockoffs internally, look pretty much like an original Toshiba 2879. Very robust.

Now then, the internals of the HG's and DEI's, look identical. Remove the top out of view and you can't tell them apart from one another.

 

[RParz]

Thats a BBI quote lol.
HG is all there is and most builders are making them work, texas star being the only exception i know of who are using supposed dei which i believe are restamped older versions of hg's. I wouldnt be surprised if the famous 6-j toshiba fakes are an older restamped hg version.

Interesting. I wonder how long until TS burns through their stockpile. I'm thinking of picking up a TS amp but I'd like for it to have HG's in it. That way the pills are easily replaceable in the future without having to rewind the transformers and the like. TS had a reputation of having a decent bias circuit for SSB and for not having any LPF being pretty clean amps when driven clean.

 

[RParz]

Those 6-J Toshiba knockoffs are definitely NOT restamped HG's .....
I have popped the top off of one and compared to a HG, very different construction internally.
The 6-J knockoffs internally, look pretty much like an original Toshiba 2879. Very robust.

Now then, the internals of the HG's and DEI's, look identical. Remove the top out of view and you can't tell them apart from one another.

They all work differently in the amp circuits though, yes? Neither of the above is a drop-in replacement of the other, are they?

 

[144inBama]

They all work differently in the amp circuits though, yes? Neither of the above is a drop-in replacement of the other, are they?

I replaced the DEIs in my TS 500V with Hgs, I made zero changes/mods and the input and output tunes were the same. I actually gained about 50 watts.

*I did talk to BBI prior and he said there were "very" minor changes you "could" make but were nowhere close to "needed"*

 

[Shockwave]

TS had a reputation of having a decent bias circuit for SSB and for not having any LPF being pretty clean amps when driven clean.

TS has a reputation for having a bias circuit. However, it is a horrible one at that. It lacks in every area from voltage regulation to thermal tracking. It also suffers from RF getting into the bias circuit, the first time you overdrive it and let the smoke out of the 10uh chokes.

 

[RParz]

TS has a reputation for having a bias circuit. However, it is a horrible one at that. It lacks in every area from voltage regulation to thermal tracking. It also suffers from RF getting into the bias circuit, the first time you overdrive it and let the smoke out of the 10uh chokes.

I guess you’re right and I should have been more specific. TS has had this design for decades and the reputation to go with it. I’m sure there’s better ways to do it, but there’s trade offs of diminishing returns. For a mass production item, they’ve always been able to hold their own. For all the types of circuits you’re talking about, there’s plenty of type approved boxes that tick these boxes. With price tags to match.

 

[Onelasttime]

I doubt that HG made changes to cut cost 6 times.

I have done business with companies in China and Taiwan and they are not as cost driven as we are. The idea of quarterly profits based on continuous cost saving like you get from General Motors with suppliers is not how they think.

You have massive increase in upstart companies due to huge number of millionaires and billionaires and low cost to open a business in China. It is very conceivable that an upstart semiconductor company could start up almost over night.

If someone will pay them to make something they have almost no fear of wondering into unknown territory or over extending themselves into an area they have no real basis competing in. A lot of hubris in China.

I have called or emailed companies in China and had them make modifications to things I was purchasing in low volumes. They never told me no and never charged me a time for the modifications I asked for. More than that just about 95% of the time the modifications I asked for became standard options or new models that appeared on the market. Clearly what I was asking for made sense to them and they figured "This guy is on to something I bet other's would like this as well!". Keep in mind I was buying like 2 or 3 here 10 items there etc....I was not some huge company placing a huge order. Obviously what I was asking for made sense! LOL TO be fair most of the companies were in Taiwan not mainland China.

A few times I looked at their catalog and suggested redesigns and or new products using all off the shelf parts from their catalog for them as a favor. They have some issues understanding what other markets want and how to be creative. They will bend over backwards though for the right customers and often at no cost.

So I can definitely see HG being a fairly young upstart with a steep learning curve and willingness to play around in markets most of us would never choose to play around in. I have experienced it first hand. They reel you in with low prices and slowly as they get their product and production up to standard the prices progressively increases.

I know nothing about HG but it is not that inconceivable. Think about it. All of the old semiconductor companies designed and built their own equipment, had their own proprietary processes in the crystal growing process etc...If you have no blue prints, no cad/cam designs to follow and you know you can not hope to reverse engineer the process or design you focus on the outcome. It is clear that HG has never attempted to copy the actual materials, process or design of the Toshiba 2SC2879. Clearly they have someone's technology and have been attempting to make something good enough based on something they already make or have the rights too. Think about it the CB illegal linear amplifier "builder" market is fairly small as is amateurs' radio operators that simply must have old obsolete bipolar HF biased transistors.

Builders are not the most discerning crowd. They just need and want a lot of cheap parts that work well enough for what they want to do. They are not investing in R&D. So given that anyone has been willing to even make old obsolete bipolar for a small market with no capital investment from the market is amazing!