[NLRS] Power on 5760 MHz

[Dr. Gerald N. Johnson]

The QFN package is tiny, terminations on 1/2 mm centers and about 1/3 mm 
wide. The terminations are not exposed to a soldering iron. There's also 
a center pad, generally bigger that is often ground and most often heat 
sink. The only way to mount is by solder reflow, hand soldering can't be 
done to mount them the way the maker intended. I suspect they might 
mount well dead bug style in a hole in the PC board with #30 single 
strand wire bridging from board to pads and copper foil to the multiple 
grounds and heat sink pad.

Big SMT resistors and capacitors are 1/8" long by 1/16" wide, often 
boards these days are using 0805 parts 80 thousandths (2mm) long and 50 
thousandths wide. They can be hand soldered, but for RF some parts get 
smaller down to 0201 and even 10 thousandths long by 5 wide. Those get 
to be hard to see with a good binocular microscope. And harder to hand 
solder.

There is a good article on reflow soldering in the latest MUD proceedings.

73, Jerry, K0CQ

On 11/7/2012 11:15 PM, tosca005 at umn.edu wrote:
>
>
> My 5760 transverter is an older 10 mW Down East Microwave model. I have a
> few options for boosting the power up to a more competitive level, but
> while browsing the listings on eBay, I came across a few items that looked
> appealing to me and might interest other folks in the same boat as I:
>
> Item 400182916307, a pair of PC boards for a RFMD/Sirenza 4.9-5.9GHz 1Watt
> SZA-5044Z RF MMIC Power Amplifier in 4mmx4mm QFN Package -- $11.99 for the
> pair, has "more than 10 available", has sold 110 of them so far.
>
> Item 260605336283, a package of 5 of the MMIC chips that fit on the above
> boards -- $13.99 for the set of 5, 3 sets available, 5 sold so far.
>
> These would provide about 22 dbm maximum output power at 5760 MHz, so a
> noticeable bump from 10 mW (10 dbm), but still pretty low. So why bother?
> Because the next item below needs 18 dbm in to produce a pretty healthy 5
> watts or 37 dbm of output power.
>
> Buy 5 of the board sets and 2 of the MMIC sets and you could build 10
> boards... Strange choice of grouping the sales if you ask me. And of
> course, you would need to add the various chip caps, chip resistors, chip
> inductor, and SMA in and out connectors, and be comfortable with surface
> mount components (which I'm not). But could be a group project if a number
> of people wanted assembled boards and someone in the group wanted to tackle
> it for those of us less adept at assembling microwave components...
>
> Then, I also saw the following item that would nicely complement the above
> pre-driver boards to bring them up to a genuine 5 watt level:
>
> Item 250983172827, a 4.8-6.7 GHz 5W Power Amplifier M/A-com MAAPGM0060 --
> from the spec sheets, it appears that 18 dbm in would give the 37 dbm (5
> watt) output that the part is capable of generating, and since the prior
> item could provide up to 22 dbm, it seems that 5 watts from 10 mW is
> doable. Unfortunately this last item is selling for $120, whereas the prior
> ones are priced low enough to entice me to experiment. As far as I can
> tell, this item is just the module itself, so a board would need to be
> created to use it.
>
> Anyone want to offer comments on these items? Or is everyone else already
> at power levels above a watt or 5 on this band?
>
> 73 de W0JT/5
>