Re: QSX radio feature requests

Hans Summers
 

Chris

Another way to look at it: even if you may argue that the LF does not care so much about a little longer wires, you are usually dealing with MOSFET devices like the IRF510 which have plenty of gain even up into the VHF region. Layout problems could create HF or VHF instabilities even in an LF amplifier.

As for sockets for chips, many are SMD that are pre-soldered by the factory. Two which are through-hole are the 8-pin dual op-amp used for microphone amps, and the 2W stereo audio output amplifier IC. I suppose you could socket them. One could argue that the heat dissipation capability of the output amp IC might be a little compromized by a socket.

73 Hans G0UPL 

On Fri, Aug 24, 2018, 15:04 ajparent1/KB1GMX <kb1gmx@...> wrote:
On Fri, Aug 24, 2018 at 02:54 AM, Chris Wilson wrote:
I would value Allison's opinion on how important FET lead lengths and
trace routing and widths, and those of FET driver IC's remain at LF
and MF as I am fond of experimenting "down there", particularly with
Class D amps. I suspect it is still important as gate and drain
traces seem to respond to careful minimisation of lead lengths and
usage of wide traces.
Its very simple, IF you want long leads stay near DC.  Look leads for high current
fast rise time pulses are essentially no different hat upper HF to VHF CW signals. 

Think of this way would you intentionally put a choke in series with the three legs?
Of course not but yet many don't consider a 40nh lead as important.

I've used those driver ICs to 13.56mhz.

More of same for wide traces and ground planes.

Or from a different view point Hans did it right and it works to VHF.

Allison

Join QRPLabs@groups.io to automatically receive all group messages.