here's a? design which I believe to be be mature that will take 3mW or so up to? 270 mW or so to drive RD15HH or similar mosfets.
No originality? claimed but? it's potentially useful to many ? well not many Qmx users ,? but hell I'ms sure Joe Biden or even? the CIA could use one.
Or indeed as a building block for the QSX.?
This OP chip from Tx has been around for quite a while and has been yanked into a? number of other? ham radio designs - which makes me suggest it is the only
one about with the HF performance and power output that can do this duty . Second source ?? prolly none.
The transformers appear to be from? Mini circuits but peoples can wind their own on bihole ferrites (generally type 43 for the IP - output side could be type 61.
NB I have some questions on how this chap has come up with the Av for the? first? chip. I get similar but not the same.? However I have to rush out will lealve for some other time.? NB nbt two - he makes claims for? Av only ,not power gain.? His claim that a given transformer is? lossless looks like Drek to me.? Trust be Verify...
Now there's a UKR outfit that is selling something like this? but with the RHS? Video amp condensed out and a cut and shut done.? Their one? is for? HF only and they claim? 10 W out at the? mosfets with? 12V Vcc and? 2mW of drive at? 50R .? I have huge reservations about that claim.? THe UKRs give no circuit details on ebay. They do give photographs of the component layout? ?and some of them concern me. I'll drop them in a later post, if any interest shown (and if their wsite is not shut down).
It appears that the? 5 plus 5? R? power resistors in the OP circuit are required to protect the OP when it is run into a nominal open circuit . Something similar appears on the? standard design cct? from Tx instruments for the intended use as a high tech communications driver? (modem duty).
I purchased? two of these chips from an Ebay seller at about? 7USD each.? That's about the going rate for suppliers like? Mouser too last time I looked.
in order to use the chip you need a Frit? to hold it and convert it to DIP or you have to design up a SM PCB.? Frits are available from likes of? Futurlec.com which is an Aussie outfit that pretends to be US based.? That's a statement not a recommendation.
Is there any other? Video amp that offers the same performance in a single chip -? does anyone know ?
Ok need to jump aboard my broom and flit off into the night....call sign for the design originator is on the lower RHS of the drafting sheet .? Looks Americano.
TEF
Timothy Fidler