Rev 24 200D Pure Signal HPF Disable on TX

jeffreydoran
Posts: 69
Joined: Sun Oct 29, 2017 9:39 pm

Rev 24 200D Pure Signal HPF Disable on TX

Postby jeffreydoran » Thu Nov 16, 2017 4:00 pm

I’ve plowed through the threads and I’m a bit confused. With a late model Rev 24 200D, using the Xtronics coupler connected to the Bypass port, 1000 watts from an ICOM PW-1, Pure signal seems to be working fine. But, should I be using ALEX “ON” (firmware control), and should HPF DISABLE ON TX, be checked or unchecked? And what is the purpose of HPF disable on TX?

Jeff NJ2US
User avatar
w-u-2-o
Posts: 2273
Joined: Fri Mar 10, 2017 1:47 pm

Re: Rev 24 200D Pure Signal HPF Disable on TX

Postby w-u-2-o » Thu Nov 16, 2017 5:30 pm

Yes, leave ALEX ON.

"ALEX" is a very poorly labeled control. In the beginnings of the openHPSDR project, the filter board was called "Alexiares" (for some reason the core developers have a predilection for naming everything after various ancient Greek deities). This control would be much easier to understand if it was labeled "PRESELECTOR".

In other words, most of the time you want the preselection filtering to be ON. Rarely do you need to turn it off, usually only when you are trying to receive in two different bands simultaneously in a way that causes the main preselection setting, which is set by VFO A, to conflict with VFO B.

You can see pretty much exactly what is going on by manipulating the ALEX button with the Setup > General > Ant/Filters > BPF/LPF window open.

For normal operations, "HPF Disable on TX" should be left in its default position, which is OFF. I don't actually know why you would want to disable it (there must be some obscure reason or application).

73,

Scott
jeffreydoran
Posts: 69
Joined: Sun Oct 29, 2017 9:39 pm

Re: Rev 24 200D Pure Signal HPF Disable on TX

Postby jeffreydoran » Thu Nov 16, 2017 5:40 pm

Thanks Scott. Evidently the HPF Disable on TX may have been used with the older revision boards that required some external patching for Pure Signal applications:

W1AEX said earlier: "With the simplest approach to this project you can run the Port A output from the RF coupler through a -20dB attenuator pad to one of the EXT ports and attempt to swamp out the internal crosstalk that is present in the ANAN 100, 100D, and 200D rigs that preceded the new PA board (Rev24) that began to appear in February of 2015. I found that this simple approach worked fine on 160 and 75 meters with ALEX disabled, "bypass on TX" checked, and "HPF Bypass on TX" checked."

I'm learning a lot from you guys, thanks again.

Jeff
NJ2US
User avatar
w-u-2-o
Posts: 2273
Joined: Fri Mar 10, 2017 1:47 pm

Re: Rev 24 200D Pure Signal HPF Disable on TX

Postby w-u-2-o » Thu Nov 16, 2017 7:20 pm

No need to over-complicate things. Just read the "sticky" thread on level calculations and you will be all set.

73,

Scott

Return to “PureSignal Operations (PowerSDR & Thetis)”