[NLRS] DB6NT Assembly progress (& PTC heater)

[Marc Holdwick]

Interesting difference.

The DB6NT 10 GHz kit I built about 2 years ago came with a PTC crystal
heater.

I am suspecting that you might not need one with your unit.

You mentioned that the 22pF was replaced with an 18pF and a 4.7pF cap.  My
guess is that DB6NT might have replaced the crystal heater with a
temperature compensating capacitor (probably the 4.7pF cap).

Did the instructions mention the PTC heater?

73,

Marc - N8KWX

PS.  I just checked my 5760, 3456, 2304 and 1296 kits and they all had PTCs.





>

> I bought one of the DB6NT 10 GHz transverter kits that Jon delivered last
> Saturday. There are a few more kits out there and a number of people were
> asking how hard it is to assemble. So I'll do a quick review of my progress
> to date. 
> 
> Monday night I spent about 2 hours slowly and carefully assembling the tin
> plate box and soldering the PCB into the box. Thankfully the end of the box
> was already punched for the connectors or it would have been a lot harder.
> I used a bench grinder to remove maybe 1/32" on the end of the long wall on
> the box. This gave it enough room to fit together in the top and bottom
> plate while I soldered the side seams.
> 
> I then used a sheet of sand paper on a flat surface to take a bit off the
> edge of the PCB so it would fit in the box. I also rounded the corners of
> the PCB a little to match the short radius corner of the tin plate box
> itself. And I sanded off a little bit more on the edge where the double
> thickness of metal is in the side plates. This "pruning" is all according
> to the assembly instructions..... GO SLOW! You don't need to take much and
> if you go hog wild you may remove so much that traces short to the side
> wall.....
> 
> I then installed the SMA connectors so I could position one end of the PCB
> on the connector pins. I maintained the same height all the way around the
> enclosure while soldering the PCB to the side walls. I used liquid flux to
> aid the soldering but in reality, the tin plate box and plated PCB solder
> together very well.
> 
> I also installed the feed-thru caps. They could have waited but it really
> didn't make much difference. The manual says to do them later.
> 
> Tuesday night I spent about 2.5 hours installing all the components on the
> top side of the PCB. I HIGHLY recommend that you have all the top parts
> installed before mounting any surface mount components. SMT parts will
> crack if the PCB flexes and for some of the top side parts, force may be
> required. 
> 
> On the 56 ohm dummy load resistor, I formed the leads so it was held off
> the PCB by about 1/16" so it is less likely to burn the PCB.
> 
> I never thought of soldering voltage regulators to the PCB for heat
> sinking, but it should work. The regulator on the side wall is taller than
> the wall itself. Instead of trying to trim the thickness of the leads, I
> just cut off the excess part of the tab before I soldered it in place. I'm
> afraid that trying to shave the lead could damage the internal connections
> to the regulator.
> 
> The jumper wire to carry 12 volts to the second regulator isn't obvious on
> the drawing. Don't forget it.
> 
> The pipe cap filters soldered together easier than I thought. The caps are
> silver plated so it was easy to tin the rim of the cap. Take care not to
> get solder on the INSIDE of the cap, it will lower the Q of the filter.
> That is also why the manual says to be careful to make sure the coupling
> pins are vertical when soldered.
> 
> I carefully centered the cap within the ring of plated ground holes before
> I applied heat. Again, I was surprised how easily the soldering iron heated
> the whole cap to melt the solder. When it did, I added more solder to the
> outside edge to form a strong fillet to mount the cap. The directions say
> to put a screw in the cap and then apply heat to the screw. I just put the
> iron on the cap about midway between the hole and the edge of the top. Just
> be SURE you don't get any solder into the threaded hole! If you are
> careful, the small amount of solder added on the top of the cap for heat
> transfer will not interfere with the screw or lock nut.
> 
> You will need a little extra space while soldering the cans of the various
> coils to the ground plane. It is easier if you do the cans before you put
> the crystal parts on the board.
> 
> The trickiest part of the assembly was when I was looking for the 22pf
> capacitor for the crystal oscillator. Low and behold they supplied an 18pf
> and 4.7pf cap which adds up to 23pf but isn't mentioned in the
> instructions.... 
> 
> Don't forget to solder the crystal can to the little ground tab under one
> corner. This adds a couple kinds of stability to the oscillator.
> 
> The PTC resistor crystal heater components are not provided but Digi-key
> sells PTC resistors so I'll be adding that to mine anyway..... And a little
> chunk of styrofoam peanut for insulation....
> 
> ----------------
> 
> Due to various commitments the rest of this week, it will probably be next
> Monday before I get around to soldering SMT components on the PCB. After
> that I should be ready for tune-up..... We'll see what happens.
> 
> 73, Doug Reed, N0NAS.
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