TX CHAIN

[Probir]

Dear All,

 

I am happy with HL2’s  recent purchase and enjoying the Receiver.

 

But for higher output if I wish to connect a LINEAR AMPLIFIER its not going to be straight forward. There has to be some switching and etc.

 

The reason I thought let do those in a neat fashion building a small PCB where in ALL extra electronics can be mounted in a separate Control BOX.

The separate control box should have some extra DUMMY PORTS and parts which will remain idle and can be utilized in future expansion and requirement as an when its needed.

 

Posting here a Schematics. I would be happy if any one can suggest what extra parts/section I can think to incorporate it – if that’s something within my design capability I will implement that too

 

The circuit description is very simple and straightforward :-

 

J1 is FED with HL2’s EXTR RCA jack at the end panel – fed to an opt isolator  to drive two relays RL1, RL2.

 

During Receive HL2 ANT output which is connected to J4 here is connected to ANTENNA through RL1.

 

When you PRESS THE MOX (transmit) RL1 activates FIRST and the ANTENNA is connected to THE output of LINEAR AMPLIFIER through RL1.

A small delay which can be achieved through C4 and C2 I believe RL2 is activated and the POWER AMPLIFIER input is connected to HL2 ANT OUT PORT also THE PTT is pressed through THROUGH RL2 at J8 PORT

THAT’S IT.

 

I NEED A SUGGESTION – R9 – is it necessary. A condition might arrive for a few millisecond during the relay switching – WHEN pressed MOX (TRANSMIT) the HL2 output which if its at 5watt full will experience NO load till its get connected to the POWER AMPLIFIER INPUT – just to avoid I HAVE used.

 

Rest all dummy parts will remain idle for now

 

I have used a sampler here too for PURE SIGNAL feedback

 

kindly send your suggestion and criticize – all accepted

 

 

 

 

 

73

PROBIR VU2BQF

[Steve Haynal]

Hi Probir,

I don't think R9 is necessary. The HL2 sequences the TR switching so will switch early enough that all relays have settled before PA power is produced. By default it is 6-10ms. You can now change this by the new TX buffer latency setting.

You may want to take a look at the HR50 works and interfaces. See DB9 level shifter board as well as the HR50 interface notes.

 

73,

Steve

kf7o