[hpsdr] PureSignal and ANAN-10

Mon Jul 21 17:30:21 PDT 2014

Thanks, Helmut, for the info.  I've learned a lot from several list 
members over the last couple of days!

I'm considering building an external T/R switch with two relays -- one 
to do the T/R, and the second to switch the RX line to the coupler on 
TX.  If I have this figured out correctly, the only mod required to 
ANAN-10 is removing the internal RX cable; you just run a single coax 
back to the "RX IN" SMA.  And since you need to supply 12V and PTT for 
the single relay version (like your design), it shouldn't be much more 
work to add the second relay to the package.

73,
John
----

On 07/21/2014 04:29 PM, Helmut Oeller wrote:
> Guys,
>
> the problem is NOT caused by insufficient grounding of the Hermes board with
> the Hammond closure etc., it's caused by the open PCB wiring of the LPF/HPF
> and ANT switching on the Alex or Anan boards. Since the early tests of PS
> nearly one year ago I'm still using my Hermes without the metal cover of the
> Hammond case plus a 1KW amp besides.
>
> 73, Helmut, DC6NY
>
> -----Ursprüngliche Nachricht-----
> Von: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] Im Auftrag von Rob
> Crewson
> Gesendet: Montag, 21. Juli 2014 19:39
> An: 'John Ackermann N8UR'; hpsdr at lists.openhpsdr.org
> Betreff: Re: [hpsdr] PureSignal and ANAN-10
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi John,
>
>     I cannot talk to the cross talk in the ANAN-10 but I have seen it in my
> TAPR Hermes and in the past in my TAPR Alex box.
>    The following points were first pointed out in the reflector  by Graham
> Haddock KE9H.
>     When Alex first came out the boxes themselves became part of the problem
> because they are anodized aluminum surface (read insulated surface).
>     Even the board to case grounding was not a sure thing unless one to steps
> to actively connect leads between the board grounds and the screws that hold
> the end plates.
>
>     On the Hammond case for Hermes my first tests with an ohmmeter showed the
> same insulated property.
>     I built up solder on the 4 grounding mount holes on the Hermes board but
> this is not much more of consistent contact with the case than before.
>     So I will be adding wires from them to bring out to the end plate screws
> as was done on Alex.
>
>     Four star washers under the screws for each end plate fixed the ground
> continuity between endplates and case.
>     But I  still detected RF from it on my Atlas machine and I remembered
> then that the sliding lid was also insulated from the reset of the box.
>     So 2 small metal screws (not the black anodized type) were added to each
> side of the sliding lid at the join to complete the continuity.
>
>    The ANAN -10 case looks anodized to me in the pictures so it could be a
> source of the problem.
>
>    Hopes this is useful info to someone.
>
> 73,
>
> Rob  Crewson VE3EW
>
>
> -----Original Message-----
> From: Hpsdr [mailto:hpsdr-bounces at lists.openhpsdr.org] On Behalf Of John
> Ackermann N8UR
> Sent: Sunday, July 20, 2014 4:44 PM
> To: hpsdr at lists.openhpsdr.org
> Subject: [hpsdr] PureSignal and ANAN-10
>
> ***** High Performance Software Defined Radio Discussion List *****
>
> I've been playing with PureSignal and it definitely works!  Using an
> external spectrum analyzer, I'm seeing a 10dB 3rd order IMD improvement at
> 100W PEP.  But I'm not sure if I've optimized the system.
>
> I'm using a TAPR Hermes mounted in an ANAN-10 enclosure/amplifier.  The 10W
> output drives a TenTec 418 amplifier to 100W.  However, I'm seeing a
> crosstalk issue similar to that reported for the ANAN-100.  I'm wondering
> whether anyone else has experimented with the ANAN-10 configuration and seen
> this.
>
> I measured the signal present at the "RX IN" SMA connector with the
> ANT-1 BNC connected to a dummy load.  The signal ranges from -37dBm at 160M
> to -8dBm at 6M.  (As usual, I've done a bunch of measurements and
> screenshots, and written up what I've learned so far at
> http://www.febo.com/pages/hpsdr/puresignal.)
>
> This makes sense when you consider that the amp/lpf board is mounted
> parallel to Hermes and only an inch or so away.  But it means that the
> sampled signal needs to be pretty strong to overcome the crosstalk.
>
> I have three questions today:
>
> 1.  Has anyone else done similar work with their ANAN-10?
>
> 2.  How much stronger (in dB) should the sampled signal be than the
> crosstalk, in order to make sure that PureSignal is correcting the whole RF
> chain rather than just the ANAN-10 amplifier?
>
> 3.  Given the ANAN-10 antenna configuration, it appears that feeding the
> sample into the SMA "RX IN" connector is the only way.  Am I missing
> something?
>
> 73,
> John
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