[hpsdr] Bare Board people

[S. Cash Olsen]

Jason and group,

The beverage warmer was in plentiful supply last year at Wal-mart but seems 
unubtainum this year, the candle warmers are a close fit and approximately 
the same function. A small chunk of aluminun with a diameter that will fit 
in the warmer surface and thick enough to get over the lip of the warmer and 
a second plate of aluminum big enough to hold the board will help adapt the 
warmer to bigger jobs. Allow significantly more warm up time with the 
adaptor.

The temperature that you are shooting for with a warming device is about 100 
degrees C. At this temperature you are somewhat less than half the solder 
melting temperature, but well within the working and storage temperatuers of 
all of the components on the board. That means that the board and parts 
could set on the warmer all day and not be harmed or destroyed.

The warmers have the virtue of using a relatively small amount of power and 
self regulate their temperature. The downside of the skillet or toaster oven 
is that they are capable of heats that are excessively hot and can destroy 
boards and parts.

To test and adjust a skillet without fancy equipment use a water droplet, if 
it sets on the skillets surface and just quickly evaporates it about the 
right temperature, if it hopps around and dances and evaporates in seconds 
it to hot. I have seen where guys uses the skillet (as with a toaster oven) 
to warm the boards and then turn up the heat to melt the solder. I have not 
experimented with this myself. I think in theory that it should work, but 
the most likely downside is that the temperature ramp up is to fast or to 
slow and I'm quite sure the ramp down is way to slow. You don't want to move 
the baord until the solder has solidified, or you'll end up with a board 
full of crystallized (cold) solder joints.

To calibrate the upper temperature setting without fancy equipment, make a 
test board, almost any scrap of printed circuit board with SMT pads will do. 
I have even used boards with chips mounted, old cell phones and such. Turn 
the temperature up until you get solder melt, it should be obvious and the 
parts will come loose or the paste will turn silver. Now you know where the 
temperature is high enough. You don't need or want the temperature to go any 
higher. Then experiment to find the settings that give you the proper ramp 
rate up and down. Like I mentioned I think the tough part is the ramp rate 
down. Remember that the temperature does not have to come back to room 
temperature but back to the storage temperature (<150 degrees C for most 
components) is good enough.

For heavens sake, experiment on some junk before you try this on you Janus 
or Ozy boards. The parts were designed to be soldered once, after that you 
stand to degrade or destroy them. So do it right the first time, if you can. 
Using a skillet or toaster oven do not easily adapt to doing sections of the 
board and testing but the hot air method can be used to do sections if 
certain cautions are observed.

Cash Olsen KD5SSJ / AAR6AP/T

Kits to build Scotty's Spectrum Analyzer http://www.zianet.com/erg
Scotty's Spectrum Analyzer website http://www.cpu-net.com/host/wsprowls
Sam Wetterlin's website http://www.wetterlin.org/sam/
Yahoo Builders Group http://groups.yahoo.com/group/spectrumanalyzer/

----- Original Message ----- 
From: "Jason Hitesman" <jason at hitesman.com>
To: "S. Cash Olsen" <kd5ssj at zianet.com>
Cc: <hpsdr at hpsdr.org>
Sent: Monday, March 05, 2007 10:25 PM
Subject: Re: [hpsdr] Bare Board people


> On 3/5/07, S. Cash Olsen <kd5ssj at zianet.com> wrote:
>
>
>> In my tutorial on this soldering method I suggest a beverage warmer, 
>> which
>> is to small for these boards so I'll have to do some retail research to 
>> come
>> up with a suitable substitute, I'm thinking that a coffee maker warming
>> plate might do the trick but that needs to be tried.
>
> Good links Cash.  I was already thinking about putting some links to
> that kind of info on there at the bottom along with the other
> resources.  Yours and Cecils will be good starting places.
>
> I've used the hot air method on my DDS-60 before and loved it.  But I
> wasn't able to find a beverage warmer.  I just kind of "eyeballed" it
> on varying the distance with the hot air.  I have an IR non-contact
> thermometer now though so that should help me be a little more
> consistent.  I'm considering an electric skillet to replace the
> beverage warmer.
>
> BTW - I've been meaning to ask you.  How warm does the beverage warmer
> get the board?  I didn't find that info on your page.  I see a lot of
> candle warmers that look similar locally for next to nothing, but
> wonder if they're in the same temp range.
>
>
>> I may also be able to assist in kitting of some of the descrete passive
>> parts and some of the semiconductor components. I'll keep you informed 
>> when
>> I know something definite.
>
> Good to know.  When the TAPR partial kits run out the Janus will be
> next to impossible to build afford ably without at least a 100 kit buy
> in due to the VXCO.  Not sure if the minimums on the other parts I
> haven't looked up yet are any worse or not. I'm not in the development
> enough to know how much interest TAPR has on this in the future.  But
> as a consumer I'm all for seeing various third party offerings
> leveraging the open nature of the project to keep it advancing!
>
> And there's also Ozy and future boards to think about as well.
>
> ----
> Jason Hitesman
> N8INJ
> 


 1173193968.0