Note: groups.io will be down for maintenance on Wednesday, October 5th, starting at 9AM Pacific Time (4PM Wednesday October 5, 2022 UTC), for approximately one hour.
- Polyphase board
Re: Polyphase board
toggle quoted messageShow quoted text
Attachments show measurements I performed here during development of these kits.
"response.gif" and "unwanted.gif" show USB and LSB (unwanted) audio response of the receiver module and polyphase module. It isn't bad for SSB. These are in the manual.
"transformer.gif" shows my measurements of the 600:600-ohm isolation transformers. They were better than I had expected. Even down at 100Hz and up above 10kHz.
73 Hans G0UPL
On Sun, Jun 7, 2020, 01:22 ajparent1/KB1GMX <kb1gmx@...
1800hz, no idea where you get that.
See the plots on the stor page http://qrp-labs.com/polyphase.html
It mentions to 1800 hz for things like WSPR and other digital modes but
the board does as shown.
1800hz for SSB would be on the narrow side. But thats not the intended application
other than incidental. Tweaking the Polyphase alone likely will not get you what
you want as its mostly GIGO.
The yabut is the 4 caps I mentioned last time and that also colors the bandwidth
as will the output transformers.
So the QDS detector caps C3-6 must be smaller.
Also the bandwidth of the 600ohm transformer will be only as specified if loaded
to 600 ohms, even then there will be significant roll off under 300hz and likely
the high side too. They are designed to old school hard-copper telephone
bandwidth (not Iphone) is 200hz at the low end is maybe about it.
Please reply on list so we can share.
No private email, it goes to a bit bucket due address harvesting
Join QRPLabs@groups.io to automatically receive all group messages.