¿ªÔÆÌåÓý

ctrl + shift + ? for shortcuts
© 2025 Groups.io
  1. Ldgelectronics
  2. Topics

LDG AT-897 v2.0 repair suggestions?

 

I have a LDG AT897 (non-plus) V2.0 I would like to repair. In the files section there is information, but that is for version 2.1.
Looking at the schematics, there is quite some similarity but also some differences:
  • There is a TLC0832 opamp that amplifies the Forward and Reverse voltage from the SWR bridge;
  • There are two potmeters that seem to adjust the voltage from the SWR bridge
  • The PIC ("897 1.7") seems to have additional debug facilites: space for a "DIAG" jumper to ground, and 3 pins labelled "serial" for debugging.
    The way these pins are connected means that the PIC is connected differently than the v2.1 schematic from the files section
?
In both the v2.0 that I have and the v2.1 from the group, capacitors and inductors are switched by 7+7+1 latching relays and the relays are controlled via two UCN5812 driver chips.
?
The AT897 "seems" to work, in that the LED does what it is supposed to do when the button is pressed. Incidentally, the relays operate, but in most cases they don't seem to do anything at all, even if I intentionally create a 1:3 SWR (I have a MFJ-251 for that).
?
I am looking for a way to test the set/reset function of each of the relays individually, and I wonder if the "diag" jumper and/or the "serial" connector can do something. And if someone has tips repairing these I'd be interested.
?
73,
?
Geert Jan PE1HZG
?
 

¿ªÔÆÌåÓý

Have you spoken with the Factory?? I just had a spectacular interaction with their Service Department, you simply can¡¯t go wrong.

?

Dave Hamm WA4WX

?

From: [email protected] <[email protected]> on behalf of Geert Jan de Groot via groups.io <pe1hzg@...>
Date: Sunday, November 10, 2024 at 15:01
To: [email protected] <[email protected]>
Subject: [ldgelectronics] LDG AT-897 v2.0 repair suggestions?

I have a LDG AT897 (non-plus) V2.0 I would like to repair. In the files section there is information, but that is for version 2.1.
Looking at the schematics, there is quite some similarity but also some differences:

  • There is a TLC0832 opamp that amplifies the Forward and Reverse voltage from the SWR bridge;
  • There are two potmeters that seem to adjust the voltage from the SWR bridge
  • The PIC ("897 1.7") seems to have additional debug facilites: space for a "DIAG" jumper to ground, and 3 pins labelled "serial" for debugging.
    The way these pins are connected means that the PIC is connected differently than the v2.1 schematic from the files section

?

In both the v2.0 that I have and the v2.1 from the group, capacitors and inductors are switched by 7+7+1 latching relays and the relays are controlled via two UCN5812 driver chips.

?

The AT897 "seems" to work, in that the LED does what it is supposed to do when the button is pressed. Incidentally, the relays operate, but in most cases they don't seem to do anything at all, even if I intentionally create a 1:3 SWR (I have a MFJ-251 for that).

?

I am looking for a way to test the set/reset function of each of the relays individually, and I wonder if the "diag" jumper and/or the "serial" connector can do something. And if someone has tips repairing these I'd be interested.

?

73,

?

Geert Jan PE1HZG

?
 

Stop


On Sun, Nov 10, 2024, 3:01 PM Geert Jan de Groot via <pe1hzg=[email protected]> wrote:
I have a LDG AT897 (non-plus) V2.0 I would like to repair. In the files section there is information, but that is for version 2.1.
Looking at the schematics, there is quite some similarity but also some differences:
  • There is a TLC0832 opamp that amplifies the Forward and Reverse voltage from the SWR bridge;
  • There are two potmeters that seem to adjust the voltage from the SWR bridge
  • The PIC ("897 1.7") seems to have additional debug facilites: space for a "DIAG" jumper to ground, and 3 pins labelled "serial" for debugging.
    The way these pins are connected means that the PIC is connected differently than the v2.1 schematic from the files section
?
In both the v2.0 that I have and the v2.1 from the group, capacitors and inductors are switched by 7+7+1 latching relays and the relays are controlled via two UCN5812 driver chips.
?
The AT897 "seems" to work, in that the LED does what it is supposed to do when the button is pressed. Incidentally, the relays operate, but in most cases they don't seem to do anything at all, even if I intentionally create a 1:3 SWR (I have a MFJ-251 for that).
?
I am looking for a way to test the set/reset function of each of the relays individually, and I wonder if the "diag" jumper and/or the "serial" connector can do something. And if someone has tips repairing these I'd be interested.
?
73,
?
Geert Jan PE1HZG
?

1 - 3 of 3