[hpsdr] Pandora

[John Ackermann N8UR]

Hi Francis --

Just a couple of quick comments:

1.  We considered a metal bracket, but it just doesn't work with the 
current cards we have to support.  The foam could break down over time, 
but it's easy to replace.

2.  We're not planning to drill the cover slots for connectors to come 
through; instead, just leaving the space open around the card. 
Fabricating custom plates for each board would have been too expensive. 
  So, the main purpose of the covers is for unused slots.  But if 
someone wants to drill the covers themselves, that may work.

3.  More generally, the enclosure is made from aluminum rather than 
steel, because that will make it easier for folks who want to do their 
own modifications.

73,
John
----
FRANCIS CARCIA said the following on 03/04/2009 08:27 PM:
> ***** High Performance Software Defined Radio Discussion List *****
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>  
> Very cool !
>  The open space. Am I to assume no smart guy is going to come up with a 
> front panel LCD display and knobs to make this stand alone with an 
> internal computer? I ask this question because I think I can build a 
> linear power supply in the open space that will provide power for a 
> final I just got going. I modified an erb tech MRI board that is now 5 X 
> 12 inches.
> Three stages push pull MRF134s, MRF148s and final MRF150s. It easily 
> makes 100 watts at 28 volts and you really have to try hard to hurt a 
> MFR150 at that voltage. Also in class A the MRF150 spec says it will do 
> -50 dB third order at 100 watts per pair. This is why I have 1200 square 
> inches of surface area for a heat sink. I read the transformer was can 
> be reversed on Penny to get more power. I have not done this.   Options 
> would to mount the amplifier in a shielded box off the back or pandora 
> or hog out a hole and mount a heat sink against the panel. My present 
> heat sink is 6 by 12 with 3 inch fins with a 5 by 12 inch slab of 1/4 
> inch copper as a heat spreader.
> I would put the amplifier in a different box if one of you guys has 
> better palns for the blank panel. I've made a number of contacts on 160 
> and 80 meters the past few days with good reports using an EV664 mic.
> My first impression looking at the trap door was supporting the boards 
> from moving. Foam usually breaks down in time. All it would take is a 
> strip of metal or plastic with slots to catch the inside corners of each 
> board. Future boards we should consider a bit more keep out area near 
> the tops of each board. Also BNC connectors should be threaded so they 
> get a good ground when passed through the slot cover. This would be a 
> good idea for Alex if it isn't too late. HP performance requires HP 
> shielding.
> I have been living in ESD fear all winter with my set up sitting on a 
> plate and was considering using an old rack mounted computer as an 
> enclosure. 
> I did some testing with a friend Sunday and he told me Penny is very 
> clean on SSB and AM. Frank WA1GFZ
> 
> 
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