Ken and others,
I'm starting some experiments with my 1 watt sdr-1000 and a prototype
PA-100 that Virgil sent me. I currently have the HF packer amp and have
been very happy with it (I built it with a input Pi attenuator that had
minimal attenuation but still 50 ohms) and find that the "1 watt" out
from the sdr-1000 (which is really more like 700 or 800 mW) just doesn't
drive the HF packer amp to its full potential. I plan to use the PA-100
to boost the sdr-1000 output to drive the HF packer. I'm going to
rebuild the pi attenuator for the HF-packer to drop the 5W out from the
PA-100 to the 1W needed by the HF-packer.
So far, I have run some basic tests with the PA-100 attached to J1 on
the BPF board on the sdr-1000 (this is the external PA output that you
mentioned is used to connect the Flexradio 100W PA). I find that it is
very easy to get 5W out of the PA-100 driven from the sdr-1000. For my
initial tests I used the PA-100 RF sensing to engage the PA-100 on
transmit and that worked fine on key down but as I found before with my
HF-packer, SSB doesn't work as well (not enough power to engage it
reliably) so I plan to use the sdr-1000 X2 PTT line (on the external
control connector) to control the PA-100. I suspect that I will be able
to use it as I have on the HF-packer by connecting it to what is pin 5
on the opto-isolator in the PA-100 schematic (my board doesn't have the
opto-isolator). With the opto-isolator it could probably go to pin 1 of
J6. This approach has worked very well with my HF-packer which uses
essentially the same circuit for keying the transmitter.
I'm also looking at the "white wire" that is attached to the junction of
D7 and R9 on the PIO board (and I assume is used as PTT to activate the
Flexradio 100W PA) but need to study how I would use that further.
I'll post some pictures and further details when I have completed my
testing. I'll be very interested in your experiences with it and the
sdr-1000 as well. By the way, you mention using it as a stand-alone 5W
sdr-1000, don't forget that the PA-100 still needs a set of low pass
filters for each band. It can drive another amplifier that has a low
pass filter but can't be used alone without one. I understand that the
filter board from the HF-packer can be used directly on the PA-100 but
that requires manual band switching and might be a bit inconvenient to
install in the sdr-1000 case. Another approach would be to make use of
the control leads from the RFE board to control a set of filters with
relays. Might need some software changes to the PowerSDR console to make
that work though.
I've cross posted this to the FlexRadio reflector as well in case others
there are interested in the PA-100 and its possibilities.
73,
Kurt KC9FOL
wb6mlc wrote:
--- In [EMAIL PROTECTED], "k5oor" <[EMAIL PROTECTED]> wrote:
>
> The PA-100 (0.1 to 5W Wide-band amp) is now available as a 5W AMP
> home construction project. Delivery is May. I can bring your project
> and hand deliver at Dayton or mail it to you. It would be a kick to
> meet you. I will be at the Friday vendor night for FDIM2006
> (QRPARCI). That is at the Holiday Inn Fairborn Dayton.
>
> We have suficient builders already signed up exceeding
> our required minimum for the project startup.
Hi Virgil,
This is great news for all! I am working on what connections are
necessary for SDR-1000 owners to use from their RFE board, or the
older BPF board for internal interfacing to the PA-100 Preamp.
There is a dedicated relay contol line meant for the Flex accessory
amp that could be used to trigger the optoisolator.One could also
connect a parallel wire to the 1 watt driver's relay coil terminals.
There is already a handy mini molex two terminal jack on these boards
for providing the exciter RF (100mw) for the PA-100 input. Also, a
prepunched hole for a panel mounted BNC jack is available on the back
panel. 12VDC can be stolen from the terminal block already available
inside the enclosure. Hookup instructions from the PDF file used
for installing the Flex accessory amp can be downloaded by the users.
I will try to compose a PA-100 specific instruction file for those
wishing to use it as a Preamp. For a stand-alone amp, they will need
to figure out how to mount the filter board in an outboard box with
the band selection rotary switch, or drill a new hole into the
existing front panel. Either DIY method should be satisfactory for a
stand-alone 5 watt QRP SDR-1000 rig. QRP enthusiasts should now
have plenty of power to make plenty of contacts with a decent wire
antenna.
73,
Ken WB6MLC
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