Pure Signal Tap

[Paul Horrox]

I have HL2 Build8 radio (bought used), running latest stable firmware and using Thetis 2.8.12 by MI0BOT. All runs flawlessly and im over the moon with its performance.

I want to use Pure signal by injecting a sample into the radio. I followed the instructions by DL1YCF and soldered an SMA cable to the jumper strip as shown in the photos (no other data that I can see)

I soldered the inner conductor across the two parallel pics RF3 and the ground in the same way. Loaded back up into Thetis but all signals were hugely attenuated and the pwr output went from 5w to 2w. I thought I had bricked it! but unsoldering the cable put the radio back to as it should be. Some other reading KF7O shows a bespoke solution using RF1 ??

I would like to know please where I should tap the bridging piece please for use with the above. Alternatively, more than happy to purchase an assembled board like the KF7O.

Thanks in advance.

Paul

["Christoph v. Wüllen"]

The additional cable should have no effect on the output signal.

It does, however, damp the input signal by about 3 dB since
the feedback is parallel to the antenna (since there is no relay
that disconnects the feedback during RX).

I attach the schematics of the HL2 and the filter board.
As you can see from the filter board schematics, at pin 6
of the connector connecting HL2 and filter board, you have
a connection with RF3, the auxiliary input used for feedback.

So the inner conductor of the feedback coax goes to pin 6, and the
sheild to pin 1, 3, 5, or 7 (which are all connected to ground).

So if this does not work, look at jumpers J1/J21 in the HL2.
If you connect your RX antenna to RF3, you should have quite "normal"
RX except that it does not go through the filter board.

[Paul Horrox]

Thanks Christoph.

Power was defintely affected by the tap I made. I cannot locate or even see the jumpers J1/J21, would you kindly show a laymans photo as opposed to a schematic. I can locate RF5 but then im a bit lost...

TIA 73