[hpsdr] PureSignal and ANAN-10

[Bill Diaz]

Rob,
     Very interesting info about the original Alex.   Thanks.

   I had one of the first ANAN-10's manufactured.  Not sure if some or 
all of the following still applies to current production radios:

       The ANAN-10 PA/Filterboard is comprised of ALEX LPF, directional 
coupler, 3 antenna ports and a 10W PA, all on one board.  No shielding 
of any kind between the board sections or between the PA/Filterboard and 
the Hermes board.  The mounting slots for the boards and the bottom 
panel located along the inside of the extruded aluminum housing were 
painted as were the insides of the rear and front panels.  The BNC, SMA 
and RCA connectors on the rear panel did not have a suitable ground due 
to the presence of this paint.   The only positive ground connection may 
be via the PA transistors mounting screws in the extrusion/heat sink.   
Note that similar construction methods are seen on my ANAN-100D, though 
there is a metal separation plate between the PA/Filterboard and the 
Angelia or Hermes board.

     While removing paint and improving contact between the boards, 
panels and the housing would surely result in some crosstalk reduction, 
having the LPF, PA and antenna relays in close proximity on the same 
board is problematic, IMO.

     The upside of this design is that PureSignal may function on many, 
but not all bands using the internal crosstalk present in the ANAN-10.

     It is possible to use an external coupler/sampler and coaxial relay 
(DC6NY design or similar) via a minor modification to the RF signal 
path.  This mod is required since the ANAN-10 K19 relay grounds the 
receiver input during transmit.   One cable needs to be replaced and 
routed to feed the RX signal to a new connector on the rear panel and 
into the coaxial relay.  During transmit the Hermes XVRT RX port is used 
to feed a coupler sample, directly to the receiver, via the coaxial 
relay.   This should reduce the crosstalk to a manageable level, IMO.  
No problem using this mod and the coupler on the output of an external 
amplifier.

     When using a similar direct receiver modification on my ANAN-100D 
with an external relay and coupler, actual crosstalk @100W as observed 
on 20 meters was reduced to about -70dbm, 55db or so below the level 
needed for PureSignal "green" level feedback.  Big improvement over the 
+8dbm or so induced by crosstalk before the modification.  YMMV.

    I have been communicating privately with John and have sent him my 
ANAN-10 Direct RF modification drawing.  Knowing John,  I am sure he is 
considering all conceivable options in great detail <grin>.

Bill KC9XG


On 7/21/2014 12:39 PM, Rob Crewson wrote:
> ***** 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
>
>


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