[hpsdr] Mounting Munin T1 & T2??

[Dick Faust]

The mounting dimensions were originally for a different heat spreader 
thickness, but modified for the 0.250" thickness.

I shimmed the 1/4" spacers with nylon spacers to get the contacts above 
the board.  Had to bend the contacts down  slightly to make contact with 
the PCB - supported the leads so they did not bend close to the body of 
the transistors.

As you can see in the photo of my board I used coax braid instead of the 
copper straps [same as Al K0VM], as they conformed better to the slight 
step down.  I pulled the braid tight and poked a hole in the center to 
pass the mounting screw with a washer. The screws were tightened down 
before trimming the braid to fit the PCB pads.

Dick

On 12/25/2013 6:24 AM, John wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
>
> Thanks for the offer Tim, but I have the straps that came with the 
> kit.  They do seem pretty thick to bend so that they contact both the 
> top of the transistor flange and the circuit board nicely.  I could 
> make thinner straps out of copper foil and probably bend them or, 
> maybe, buy some copper of the right thickness to fill the void between 
> the top of the heat spreader and the straps I have.
>
> Dick, what I'm trying to say is best described in the mechanical 
> drawing of the RD100HF-1 data sheet available here:
> http://www.mitsubishielectric.com/semiconductors/content/product/hf/sirfpowermosfet/siliconrfdiscrete/siliconrfdiscrete_lv4/rd100hhf1.pdf 
>
>
> The thickness of the flange is 3.3 +/- 0.2 mm but the bottom of the 
> other leads is 4.5 +/- 0.7 mm above the bottom of the flange. The 
> problem I see is that when I make the four mounting posts for the 
> circuit board so that the drain and gate leads are flush against the 
> pads on top of the board, the top of the flange (source connection) is 
> a considerable distance (nominally 1.2 mm) below the top of the 
> circuit board.  I do not understand how the drawing on page 2 of 
> Mounting the RD100HHF1
> http://www.k9ivb.net/Munin2/Mounting_The_RD100HHF1.pdf
> applies.  That drawing shows the RD100HHF1 flush with both the heat 
> spreader and the top surface of the circuit board.  One of the 
> pictures on your site shows the straps are flat and the other picture 
> shows them bent, but the bent ones don't look as if they are bent 
> enough to reach the top of the flange.
>
> John, WoGN
>
>
> At 03:51 PM 12/24/2013, Tim ORourke wrote:
>> If you refer to wiki munin page you will see brass straps bent to 
>> accmodete the raised mounting tabs. I can send you some straps if you 
>> do not have a way to make them. Tim w4yn
>>
>>
>>
>>
>> -----Original Message-----
>> >From: John <radio at mediacombb.net>
>> >Sent: Dec 24, 2013 4:09 PM
>> >To: bob at llorenzini.com, "hpsdr at lists.openhpsdr.org" 
>> <hpsdr at lists.openhpsdr.org>
>> >Subject: Re: [hpsdr] Mounting Munin T1 & T2??
>> >
>> >***** High Performance Software Defined Radio Discussion List *****
>> >
>> >
>> >Hi Bob,
>> >
>> >I don't think that document applies in my case.  With the transistors
>> >I got with my kit, and with the four board mounting spacers made so
>> >that the tops of the transistor flanges are flush with the top of the
>> >circuit board, the other transistors leads are way above the level of
>> >the top of the board.
>> >
>> >John,  WoGN
>> >
>> >
>> >At 01:35 PM 12/24/2013, Robert Lorenzini wrote:
>> >>On 12/24/2013 11:25 AM, John wrote:
>> >>>***** High Performance Software Defined Radio Discussion List *****
>> >>>
>> >>>
>> >>>
>> >>>Transistors T1 and T2 in my Munin kit are made with the two thin
>> >>>leads a considerable distance above the top of the mounting
>> >>>flange.  When the four corners of the circuit board are spaced so
>> >>>that the two thin transistor leads are flat against the pads on top
>> >>>of the board, there is considerable distance between the bottom of
>> >>>the copper straps and the top of the transistor flange. As
>> >>>transistor hardware is tightened the board starts to bend and the
>> >>>transistor leads lift above the pads on the circuit board.
>> >>>
>> >>>Has anyone else had this problem and, if so, how did you make it 
>> work?
>> >>
>> >>Your going to need to make custom spacers.
>> >>
>> >>http://k9ivb.net/munin2/Mounting_The_RD100HHF1.pdf
>> >>
>> >>Bob - wd6dod
>> >
>> >
>
>
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