Topband: Hi Z amplifiers for 160m

[Mike Waters]

On Thu, Mar 12, 2020, 3:48 PM Michael Tope <W4EF at dellroy.com> wrote:

> There are a lot of SMT to DIP adapter boards out there which would allow
> newer SMD op-amps to be used in older through-hole PWB layouts.
>
>
> https://www.digikey.com/product-detail/en/aries-electronics/LCQT-SOIC8-8/A880AR-ND/4754588


This is great advice, which I think a lot of folks are too quick to dismiss
in this era of vanishing through-hole DIP ICs and transistors with wire
leads.

I successfully did just that with an SO-23 (VERY tiny SMD package) J310
transistor. It was not only my very first attempt at soldering with solder
paste and hot air, but it was the easiest thing that I ever soldered! (And
I've soldered north of two million connections.)

Squirt a *small,* even line of solder paste through both rows of bright
copper pads, place the SMD device onto the paste, and a heat gun from the
underside of the (level) adapter board will make the solder flow exactly
where it should. It'll look like it was professionally machine-soldered.

FORGET trying to solder an SMD device using the regular method! Even with a
bright light and a magnifying headband, it just makes a mess, pushes the
SMD device around, and the solder bridges are difficult to clear.

Mine did not have the DIP plugs as this one does, just holes for small wire
leads.

Solder paste (a powdered solder and flux mix) can be somewhat expensive,
and IIRC it has a shelf life of less than 5 years. But I found a guy on
eBay who repackages a big jar of solder paste into small syringes for
cheap. He even included two different size nozzles. Don't know if he's
still in business, but there was a nice instructional video that will make
believers out of any "Well, I couldn't do that" skeptics reading this.
Sorry that I don't have a link handy. Last time I looked, YouTube had
several very good videos on this method of soldering. Qrz.com has threads
about this method, you might search there also.

Keeping the paste in your refrigerator in a small Ziploc bag will lengthen
its useful life.

It would take very fine wires indeed to solder small tinned wires directly
to those tiny devices. Just get an adapter board. Trust me. :-)

73, Mike
W0BTU