What is the red wire (that comes coiled with the kit)?

[K7RAN]

Hi, I apologize up front for what's undoubtedly a dumb question, but here it is regardless: What is the little coil of red-insulated wire that comes with the HL2 kit? It looks like it's the only thing that requires soldering. Thanks, and 73,

Randy K7RAN

[Colin Larsen]

It's there in case you want to rewind the finals output transformer from memory

Colin

ZL2FL 

On Wed, 9 Aug 2023, 17:22 K7RAN, <pad...@gmail.com> wrote:

Hi, I apologize up front for what's undoubtedly a dumb question, but here it is regardless: What is the little coil of red-insulated wire that comes with the HL2 kit? It looks like it's the only thing that requires soldering. Thanks, and 73,

Randy K7RAN

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[K7RAN]

Aha, thank you, Colin. I'm relieved to know that doing that is optional. Follow-up question: And what would be the benefit of rewinding the finals output transformer? 73, Randy K7RAN

[Rick Langford (N8SDR)]

Possible slight increase in output power, if I recall correctly 

[Steve Haynal]

Hi Randy,

Makerfabs has to wind the large TX balun by hand. Early HL2s sometimes had low power due to loose windings. The solution was to include this wire so that people could rewind the TX balun if required. It is a special wire with high temperature insulation. Makerfabs now does a much better job of winding the TX balun and the wire is probably never required. The rewinding instructions are here:

https://github.com/softerhardware/Hermes-Lite2/wiki/Build8-Notes#tx-transmit-balun-winding

73,

Steve

kf7o

[Pez]

Hi Steve, 

Where it says:  Increase PA Driver: "R55 is circuled in red on the bottom of the HL2 PCB. Remove R55 and replace with the 100 Ohm resistor provided in the kit."

Do build 9 boards now come with the 100 Ohm resistor already fitted? (Any minor increase in power would make my amplifier happy! :) )

73

[Mark R]

@pez

I just got 2 boards from makerfabs. Both have a 120 ohm resistor.

[Steve Haynal]

Hi Mark and Pez,

The LDMOS devices on the newer HL2s are different and use 120Ohm for R55. Search this group if you want more details on R55:

https://groups.google.com/g/hermes-lite/search?q=R55

You can tweak the power output, but only by maybe 1 or 2 dB and still be clean. The N2ADR filter board also imposes limitations (parts used are expecting 5W). Finally, Vpa of 8V is also related to maximum power.

73,

Steve

kf7o

[Pez]

Thanks for the info Mark and Steve. All good! 

73