[hpsdr] Pennywhistle capabilities question

[Dave Watson]

Sid,

I found some info on the SoftRock forum but instead, I was thinking about
duplicating the RF sensor (4N33) and relay used on my hfpacker PA100 so that
there is no direct connection between the trigger circuit and the
transmitter other than the input RF. It's more of a learning exercise
coupled with a strong desire to put the PennyWhistle into service running
WSPR at 5 watts full time.

Can't wait until the Hermes is available, it's high on my "want one" list.

Dave (W4DJW)

-----Original Message-----
From: hpsdr-bounces at lists.openhpsdr.org
[mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of Sid Boyce
Sent: Sunday, September 04, 2011 4:34 PM
To: hpsdr at lists.openhpsdr.org
Subject: Re: [hpsdr] Pennywhistle capabilities question

***** High Performance Software Defined Radio Discussion List *****

Dave,
I'll have to check the Softrock circuitry later.
Essentially what you are getting is the same as if you have a separate 
receiver close by whilst transmitting.
Enough signal will reach the receiver if the antenna socket isn't grounded.

Posting to the softrock40 group would get you more information as it's 
just a case of adding a PA of any description to a Softrock RXTX.
I've got a SR63ng + Mobo v4.3.4 + SDR-Widget + 20W PA that suffers from 
a si570 hang on TX.
I haven't got around to looking seriously at it so far as I'm busy 
trying to put together some add-on circuitry for the HiQSDR, a sort of 
little brother to Hermes by DB1CC, described at hiqsdr.org and based on 
a design by N2ADR which was featured in a recent QEX article.

It's running on RX currently but needs needs a set of RX BPF's and a 
case. I already have 15W and 5W PA's ready for it  to use standalone and 
to drive a AN762 to 140W and a EB104 for 300W for 3W input.
73 ... Sid.


On 04/09/11 19:37, Dave Watson wrote:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Thanks for the quick reply George. I thought that was the case. I really
> like the PennyWhistle so I think it will be worth and additional
controller
> board to switch the RX/TX on both sides (DPDT).
>
> Dave (W4DJW)
>
> -----Original Message-----
> From: hpsdr-bounces at lists.openhpsdr.org
> [mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of george byrkit
> Sent: Sunday, September 04, 2011 1:20 PM
> To: hpsdr at lists.openhpsdr.org
> Subject: Re: [hpsdr] Pennywhistle capabilities question
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> Dear Dave,
> The PennyWhistle is a transmit-only device.  You would not be able to get
an
> RX signal back thru it.
>
> Typically, the RX/TX commutation device referred to by Roland is called a
> 'T/R switch'.  Gerd has them for sale, and Alex includes one as well.
But
> for reasons explained below, I don't think either is appropriate for you,
> currently.
>
> The PennyWhistle works best in a situation like PennyLane (or Penelope)
and
> Mercury, where each has its own antenna connection.  Thus, a T/R switch
> after PennyWhistle works well to switch the antenna to TX (signal from
> Penelope thru PennyWhistle to antenna) or RX (antenna connected to
Mercury).
> With something like a SoftRock, where there is only one antenna
connection,
> you need a more complicated T/R switch (DPDT, rather than SPDT, and
isolated
> sections for the DPDT) that can completely bypass PennyWhistle, while at
the
> same time likely terminating the input to PennyWhistle so that it won't
see
> a signal to amplify.  Floating inputs can be a problem!
>
> Duplexers aren't very practical at HF frequencies, because of their large
> physical size.  ALso, they are relatively narrow in bandwidth, say,
compared
> to 1.6mHz thru 50mHz.  They are also a better fit, say, for a repeater,
> where there is simultaneous TX and RX (albeit at somewhat different
> frequencies!), and the TX and RX have separate antenna connectors.
>
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-- 
Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
Senior Staff Specialist, Cricket Coach
Microsoft Windows Free Zone - Linux used for all Computing Tasks

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