[NLRS] 10 GHz kits

[Doug Reed]

At 09:43 PM 1/2/2003 +0000, kb0mnk@visi.com wrote:
>If it makes a differnce for anyone thinking about a kit and getting on
10GHz I 
>would be willing to help tune it up. I have a power meter, attenuators,
12.4GHz 
>freq. counter, Rubidium clock, an older spectrum analyzer and several 
>synthesizers. It makes tuning pretty easy.
>>Quoting "mike@KB0OZN.com" <mike@KB0OZN.com>:
>> Hi Jon and all, I'd like to echo the interest in a kit, but am concerned
>> about the complexity of tuning etc.  Any information would be great.
>> Thanks
>> Mike
>> KB0OZN

I'll join in with a little hear-say too. I spoke with Marc at the Aurora
meeting when he was showing the kit. I was intrigued that it was so small.
Since I'm working with surface mount every day, the "large" 1206 size parts
didn't scare me but I was worried about tuning. He said the kit was
designed with metering points for each tuning stage similar to the way it
is done in Motorola or GE two-way radio gear. The whole tune-up can be
accomplished with a volt meter. Of course you'll probably need a signal
generator to verify receive operation, a frequency counter to put the LO on
frequency, and the power meter to verify you have output. 

I think the only negative comment he had was regarding soldering the
tin-plate box around the board and either not getting the right height or
ending up with pre-drilled holes for feed-thrus in the wrong place.
Something similar to that anyway.....

I've been intending to order the kit this winter. If there is a way to
shave another $100 off the price, I'm even more interested. 

And I'll throw my hat in the ring to help getting them going if needed. I'm
pretty sure the 18 GHz spec-an at work can help with tuneup of the LO and
transmitter chain. But we don't have a 10 GHz signal generator for receiver
tests. 

The single most helpful piece of equipment for surface mount work is still
a microscope. That plus a very small point on the soldering iron and very
small diameter solder. I find 7x power to be just about perfect, more than
10x is too much. The microscope and a strong light make checking your
solder joints pretty easy. Since you probably don't have a scope, just use
anything that will get you some magnification and a strong light to work
under. A 10W or 20W halogen lamp at 6" or a 60W incandescent lamp at 2',
not the overhead ceiling lamp.....

The easiest technique is still to have a little bit of liquid or paste flux
on the board, place the part in the flux with tweezers, then hold it GENTLY
with a toothpick (or non-magnetic tweezers) while touching the solder iron
tip (with solder) to one end of the part. When you get all the soldering
done, use rubbing alcohol and a soft "acid brush" to clean all the flux off
the board. The less flux residue left on the board, the fewer problems
you'll have with sensitive parts like mixer ICs..... The flux we use at
work is a "no clean" flux that is very inactive, but I still clean it off.
And you don't need much flux. Using a Q-tip to mop the flux on the pads and
remove all but a thin film is about right. 

Another option for soldering is to put a small layer of solder on ONE pad
of the part. Then add flux, lay the part in place, hold it GENTLY while
applying heat to the solder on the pad. The part will sink into the solder
and be soldered and stuck in place when you remove heat. Solder the other
end, then come back and finish soldering the first end. As long as you're
using flux, the joints should come out OK. 

The only other thing I can think of to caution about is the soldering iron
itself. A 600 degree tip should be perfect for soldering small surface
mount parts. A hotter iron begins to raise the possibility of damaging the
PCB traces if your soldering technique isn't good enough. I always got by
pretty well with a pointy tip or a flat chisel tip. The common chisel tip
is about 1/8" wide and I usually found myself using just one corner of the
tip. I don't remember looking closely at the DB6NT board but I assume the
parts are not super close so having a tip that is slightly too large may
not be the end of the world. 

If at all possible, try to have a grounded tip soldering iron for doing any
semi-conductors. If the iron isn't grounded, the first touch could blow out
a transistor or mixer chip. They have even replaced the older Weller "click
thermostat" irons at work because they might generate a magnetic field and
blow out some of the more sensitive chips we use. I don't think that should
be a problem for this project and the old Weller soldering station is all
I've used for surface mount the previous 8 years. Worst case, you can heat
your old ungrounded solder iron up, unplug the cord and ground it before
soldering the ICs. Then plug it in and heat it up again..... But with luck
and good anti-static technique, it shouldn't be a problem.... Good luck!

How about that.... Two paragraphs on the kit and 5 paragraphs on
microscopes and soldering irons..... Just a bit off topic....<g>

73, Doug Reed, N0NAS.