As I pointed out, this tap location is not the same as the rx out to rx in loop
you describe in that it doesn't need an external switch and it takes advantage
of the mp's pre 1st stage rf amp bandpass filters, attenuator, and the 1st rf
amp as a buffer, so it is protected from picking up other local station's
signals, very important in m/m station. Using the rx out to rx in loop would
expose the sdr-iq to overload from other transmitters and also would rely on
the external switch for isolation from the transmitter it is connected to...
and might also affect the main rx by either attenuating the incoming signal or
allowing noise to be injected.
The impedance of that line appears to be relatively low, after the transformer
on the rf board there is an attenuator using 220 ohm resistors to ground. I
put in a 1uv signal on 40m and could see no change in the sub rx signal level
with or without the y and with or without the sdr-iq connected to it so I am
confident the loss of sensitivity will be negligible... and it is only on the
sub rx which is not the best rx to listen on anyway.
As far as the physical aspects of the mod... it has no permanent change to any
board, can be installed and removed in about 5 minutes(mostly time taking out
and putting in the top case screws), and requires no case modification if you
just route the cable out the top access panel.
I am now testing it on one radio of my so2r/40m station and it seems to be
working well.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
-----Original Message-----
From: Joe Subich, W4TV [mailto:lists@subich.com]
Sent: Tuesday, July 11, 2017 13:40
To: k1ttt@arrl.net; Yaesu reflector
Subject: Re: [Yaesu] ft-1000mp mod?
On 7/11/2017 8:51 AM, David Robbins wrote:
> Hmmm, simple option, no board modifications, easy access, no
> measurable change to rx I can see... after going through the rf board
> bandpass filters the rx rf is split to go to the first mixer to get it
> to 70MHz for the main rx, and to be sent to the sub rx board.
That is electrically the same as connecting a splitter to the RX ANT Out with
one output of the splitter going to the SDR and the other back to RX ANT IN or
the external RX ANT switch. The advantage of RX ANT Out is that it requires no
internal changes in the transceiver and no holes for a connector/cable.
> It is very convenient to unplug the red rf input coax at the top back
> of the sub rx, put in a Y cable, and send that to the sdr.
Be careful of simple "Y" cables. If the input impedance of the Sub Rx and the
SDR are not well controlled one can "load" the other. If you are tapping the
receive antenna *after* Yaesu's internal splitter you will never see a level
shift in the main RX ... only (potentially) in the sub RX when it is enabled.
You can avoid any potential level issues by using a quality splitter rather
than a "Y" cable.
73,
... Joe, W4TV
On 7/11/2017 8:51 AM, David Robbins wrote:
> Hmmm, simple option, no board modifications, easy access, no
> measurable change to rx I can see... after going through the rf board
> bandpass filters the rx rf is split to go to the first mixer to get it
> to 70MHz for the main rx, and to be sent to the sub rx board. It is
> very convenient to unplug the red rf input coax at the top back of the
> sub rx, put in a Y cable, and send that to the sdr. This has a big
> advantage for me in that it is already bandpass filtered by the
> radio's rf board which will remove most of the signals from the other
> stations in multi-multi contests. it also will let the operator see exactly
> what is on either his tx or separate rx antenna.
> And it is muted by the t/r relay when the radio transmits. And
> requires no external relay to switch the rx antenna.
>
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373
>
>
>
> -----Original Message-----
> From: Yaesu [mailto:yaesu-bounces@contesting.com] On Behalf Of David
> Robbins
> Sent: Monday, July 10, 2017 14:24
> To: 'Yaesu reflector'
> Subject: [Yaesu] ft-1000mp mod?
>
> Has anyone seen or done a modification to the ft-1000mp to enable
> using whatever antenna is being used on receive to be shared for use
> by an sdr for a waterfall display??
>
>
>
> David Robbins K1TTT
> e-mail: <mailto:k1ttt@arrl.net> mailto:k1ttt@arrl.net
> web: <http://wiki.k1ttt.net/> http://wiki.k1ttt.net AR-Cluster node:
> 145.69MHz or <telnet://k1ttt.net:7373>
> telnet://k1ttt.net:7373
>
>
>
>
>
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