Re: TGA2760-SM


Eric Haskell <eric_haskell@...>
 

>{I'm trying to work out if I can machine out a hollow in solid copper
but leave a rectangular post in the centre the thickness of the PCB,
then cut a rectangular hole in the centre of the PCB, fit the PCB over
the post, and solder the PCB to the copper and the device to the PCB and
copper post using 138C bismuth-tin like I did for the 23cm PAs. Might
be a lot simpler than getting a PCB made with hundreds of teensy pths.
Wouldn't work for mass production, but maybe feasible for a one-off.
This hobby gets more like jewellery-making by the minute...
Neil G4DBN}

Neil,  I wounder it it might be easier to cut a rectangular copper slug the size of the ground on the bottom of the part and same thickness as PCB.  Have a PCB made with a rectangular hole. Solder all the other parts to the PCB.  Insert the slug into the rectangular hole in the PCB.   Lay PCB and slug on a pre-tined copper heatsink siting on a hotplate and reflow together.  Then apply solder or solder paste to device area of PCB and reflow device onto PCB. Add edge mount SMA connectors and solder on a sheild.  We may need to take some the the thermal CTE is matched fairly close between copper slug and PCB substrate material so that thermal expansion does not pull everything apart.  Also thinking about paralleling 2 parts with Wilkinsons for more power. Seems like a good fit for constant envelope modulation modes or CW with the high saturated power output.

Eric Haskell,
KC4YOE





To: ukmicrowaves@...
From: ukmicrowaves@...
Date: Sun, 4 Sep 2016 21:47:11 +0100
Subject: Re: [ukmicrowaves] TGA2760-SM

 
I'm trying to work out if I can machine out a hollow in solid copper
but leave a rectangular post in the centre the thickness of the PCB,
then cut a rectangular hole in the centre of the PCB, fit the PCB over
the post, and solder the PCB to the copper and the device to the PCB and
copper post using 138C bismuth-tin like I did for the 23cm PAs. Might
be a lot simpler than getting a PCB made with hundreds of teensy pths.
Wouldn't work for mass production, but maybe feasible for a one-off.
This hobby gets more like jewellery-making by the minute...
Neil G4DBN

On Sun, 4 Sep 2016 20:52:12 +0100, Andy Talbot andy.g4jnt@...
[ukmicrowaves] wrote:
> Make sure you use the proper PCB layout then - I was looking at the
> data sheet for it and see the cooling needs ot be  via hundreds of
> plated though holes to the lower ground plane face of the PCB and
> thence to the heatsink.   So getting rid of tens of watts of heat
> needs proper attention to PCB detail.  
>
> But youre right - it does seem very cheap for that sort of Psat.   
> ... and only needing a few milliwatts of drive too...
>
> jnt
>
> On 4 September 2016 at 20:45, Neil neil@... [1] [ukmicrowaves]
> wrote:
>
>>  
>>
>> The device looks like a three-stage MMIC, running with the finals
>> at
>> 28V, but it still seems weird that the P1dB is only 2 watts or so
>> when
>> Psat is about 15 watts. For the price, it looks like a brilliant
>> deal
>> to get serious power on CW/JT modes on 3cm, but would it be
>> feasible to
>> use predistortion on an SDR IF rig in SSB mode to get a fairly
>> linear
>> response at high power, despite what looks like unspeakable
>> nonlinearity? After all, a pair of these 60 quid devices gives as
>> much
>> power as some of the 0-0 GaN PA MMICs.
>>
>> Perhaps the answer is to get a couple and play with them and see
>> what
>> happens.
>>
>> Neil G4DBN
>
>
>
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