PA stands for Purple Amp.


Curt wb8yyy
 

Ron

wow - very nice.  I agree the appearance is much more commanding with the heat sink external. 

assuming you plan to major on 50 MHz and less - that run of coax is quite short in wavelengths.  wire may have worked as well - but fine as is.  if you convert the distance to degrees - you would see it is quite small. 

I am finding that milliwatts is enough for WSPR in the middle of the HF spectrum, but that PA should come in handy on the lower bands if your antennas are less than ideal there.  enjoy. 

Curt


Facility 406 <facility_406@...>
 

"...RG-174 pieces for making the connection. Any suggestions about a better
way to do it?"

I'd try to mount he board closer to the top of the box, if necessary, and
try to use an elevated socket, myself.

Kurt


WB8LZR - Ron <ron@...>
 

The amp should come in handy ... most of my antennas are in the attic :-)

I love those Hammond aluminum boxes.  All kinds of colors - pretty decent quality, and fairly inexpensive as well.  The amp and LPF boards (2 or 3) will go into the box shown in the pics, and the Progrock and RX stuff will go into another box (same type and color, but slightly bigger).

  - Ron


WB8LZR - Ron <ron@...>
 

"I'd try to mount he board closer to the top of the box, if necessary, and try to use an elevated socket, myself."
Thanks for the suggestion Kurt.  I hadn't thought about that one.  You're saying that I could have made the alignment work out better, such that I might have plugged the amp board directly into the headsink/roof, rather than use the cables.  I've already drilled the holes, though ...


Facility 406 <facility_406@...>
 

"Thanks for the suggestion Kurt. I hadn't thought about that one. You're
saying that I could have made the alignment work out better, such that I
might have plugged the amp board directly into the headsink/roof, rather
than use the cables. I've already drilled the holes, though ..."

Actually, I was thinking of the current design with the transistor on the
lid, in the sink, with the board in the bottom. This makes it so the lid
can be removed, but not physically attached to the rest of it. You unscrew
the lid, it would still be held by the transistor, plugged into the board
below, but a little tug and it comes loose.

The other way, if possible, could be to mount the PCB to the lid with
standoffs, solder side toward the lid, and I'm not familiar with that amp,
but if the transistor is desiged to be on the top of the PCB, rotate it to
the bottom of the board, maybe flip 180º and run leads a short ditance
through the lid to the outside. What you would have is the lid sandwiched
between the PCB and heatsink, all in one secure unit and just the box is
free and removeable.

Kurt


WB8LZR - Ron <ron@...>
 

On Wed, Jul 19, 2017 at 08:32 pm, Facility 406 wrote:
What you would have is the lid sandwiched
between the PCB and heatsink, all in one secure unit and just the box is
free and removeable.
Kurt:

You've convinced me.  That'll be a much cleaner setup, with everything mounted on the lid.  It'll have no messy wires at all.  I have a couple Pi projects where there are wires between the lid and box, and I always have to be so careful taking those things apart, and putting them back together, so as not to pinch anything.  You're idea much better.

    - Ron 


Facility 406 <facility_406@...>
 

"You've convinced me. That'll be a much cleaner setup, with everything
mounted on the lid. It'll have no messy wires at all."

I'd make certain the holes are large enough to prevent shorting and use some
nylon or ceramic insulators like beads, tubes, or shoulder washers where the
wires/pins go through the lid to protect the leads and keep out dust. Yes,
the box becomes the lid. Be certain you get the transistor orientation
right, since it will be flipped!

Kurt


WB8LZR - Ron <ron@...>
 

On Thu, Jul 20, 2017 at 09:48 pm, Facility 406 wrote:
I'd make certain the holes are large enough to prevent shorting and use some
nylon or ceramic insulators like beads, tubes, or shoulder washers where the
wires/pins go through the lid to protect the leads and keep out dust. Yes,
the box becomes the lid. Be certain you get the transistor orientation
right, since it will be flipped!
Thanks for the caveats Kurt!  I'm still conceptualizing the layout.  I've build the driver board, progrock, LPFs, BPFs, TTL/RS232 converter, and the PA kit, but not yet the receiver.  I've created a block diagram for it, using Gimp (had too much time on my hands this AM!)  I know it's not using proper schematic symbols, but my Gimp-techniques are a little too lacking for that!.  Anyway, it seems to be a lot to fit on the lid:


WB8LZR - Ron <ron@...>
 

I show a direct connection from the Progrock to the RX, but I suppose that line should be loosely coupled or attenuated.


Larry Acklin
 

no, a direct connection.  I had an early Rx using the VFO kit, and it works with direct connection.  The Tayloe detector does not mind actually prefers being driven to saturation



73
Larry
KB3CUF



On Fri, Jul 21, 2017 at 1:00 PM, WB8LZR - Ron <ron@...> wrote:
I show a direct connection from the Progrock to the RX, but I suppose that line should be loosely coupled or attenuated.



Larry Acklin
 

Sorry- the clip did not work

On Fri, Jul 21, 2017 at 1:08 PM, Larry Acklin <acklin@...> wrote:
no, a direct connection.  I had an early Rx using the VFO kit, and it works with direct connection.  The Tayloe detector does not mind actually prefers being driven to saturation



73
Larry
KB3CUF



On Fri, Jul 21, 2017 at 1:00 PM, WB8LZR - Ron <ron@...> wrote:
I show a direct connection from the Progrock to the RX, but I suppose that line should be loosely coupled or attenuated.




WB8LZR - Ron <ron@...>
 

Hi Larry.  Thanks for the tip about the RX input, and for the schematic as well. 

I wonder if you've worried much about section shielding within your projects, relative to the idea of putting components inside their own copper clad compartments.  I've noticed that Qrpers often forgo the idea of sectioning ...


Larry Acklin
 

well, I do shield if possible, but I'm not crazy about it.  The progrock is tiny, I'd shield it with a cut down soup can or the like.  The Bitx folks have been using plastic boxen with copper or Al flashing (the adhesive foil) to shield their noisy Arduinos and supplies.  


That's a wooden cigar box and Al flashing tape from the roll.


I found that the environment was even more critical- I had a USB charger IN THE SAME ROOM as the RX kit/VFO and it totally flooded the band with RFI.  It was trash binned as soon as I realised.


Larry




On Fri, Jul 21, 2017 at 1:31 PM, WB8LZR - Ron <ron@...> wrote:
Hi Larry.  Thanks for the tip about the RX input, and for the schematic as well. 

I wonder if you've worried much about section shielding within your projects, relative to the idea of putting components inside their own copper clad compartments.  I've noticed that Qrpers often forgo the idea of sectioning ...



WB8LZR - Ron <ron@...>
 

Larry:

LOL - sure beats the price of the copper clad!!!   I'm sure it works just as well.

I had a 12 VDC wall wart that I purchased online for something in the shack.  Didn't do anything radio related for a couple weeks, and when I came back (having forgotten about the new wall wart) - I had to investigate a new S6 noise source that was fouling my Ten Tec Omni's RX.  That was found, and went to the same place as your USB charger.

My BS170 driver could have been done on half the board, I see now that I snap a pic.  That's what I get for doing things without the magnifier.  I'm sure the old-time proto board get's a laugh or two, as well  ... 


WB8LZR - Ron <ron@...>
 

So, as I keep fleshing the thing out, it gets more and more messy.  Still, I like the idea of separate RX and TX boxes, which currently are small/cute.  Putting everything into one big box makes the radio too much like my Omni (which is OK for what it is).

I'm thinking I can get rid of the antenna switching relay with a COR like at:

http://www.kolumbus.fi/oh5iy/HW/Homebrew.html. 

Guess the idea is make sure V+ is not applied to the PA until it has a load (otherwise oscillation).  Few more items added here, which were left out of the original block diagram:


WB8LZR - Ron <ron@...>
 

Oops - found a few more missing items.  I guess block diagramming with Gimp is not my thing:


Facility 406 <facility_406@...>
 

"You've convinced me. That'll be a much cleaner setup, with everything
mounted on the lid. It'll have no messy wires at all. I have a couple Pi
projects where there are wires between the lid and box"

I was playing with some parts and a board, the transistor, on the bottom
does NOT flip 180º, pin-wise. Don't know what I was thinking. Look at your
amp from the side, then just rotate the transistor around clockwise to the
side until underneath, for example, same pin alignment, just on the bottom
now, through the lid, and on the outside. You'll have to get your soldering
iron between the lid and board, so longer stand-offs would be better, maybe
use a light and magnifying specs, have the solder-side up and the lid on top
to help with wetting and flow, or use/make a socket, the transistor
hard-mounted to the lid, the board slid down onto the transistor. In the
past, for various things, I've pulled pins from a socket, such as a data
connector, Canon plug receptacle, what have you, and put the female portion,
of the correct size in place of a component, so I can swap parts in and out
for testing. These are a lot longer than just a board mounted socket, some
almost an inch in length, plenty to get outside of the lid.

Kurt


WB8LZR - Ron <ron@...>
 

I show hookup wire coming from/to the driver, but it won't be that way for long!  Will run ferrite loaded mini-coax for the connections. Since I'm moving things around (making the IRF-510 remote from the original board, for instance) - I'm wanting to keep everything cool in case I've promoted any instability.  So, we'll probably put a bias control in there similar to what's shown on this page:

http://www.g0kla.com/scpa/SimpleCheapPA.php

It's the second schematic.  Apparently, this fellow got tired of replacing the burned-out FETs!

 -- Ron


WB8LZR - Ron <ron@...>
 

The COR cirucuit shown in the link (back a few messages) is OK I guess, but here's a cute little RF sensing T/R circuit utilizing a 2N2222:

https://www.rcarc.org/presentations/AB2EW%20Class%20C%20club.pdf

Picked up a few other hints from that page, as well.  Good read.


WB8LZR - Ron <ron@...>
 

BTW: The RF sense circuit is on page 19 of referenced rcarc page link.
 
  - Ron