[hpsdr] OpenHPSDR, Apache Labs and Firmware

[Joe Martin K5SO]

Hi Jean-Claude, 

Although I have not had any direct communications with Abhi on what this change actually is, I strongly suspect that what he provided to you is a simple change in the LPF_select.v module of the Hermes v2.5 code that assigns the frequency switch points for the LPF on the ANAN-series PA, specifically modified for use with the ANAN PA.  The change he posted likely moved the switch point for the 12m band Tx operation to use the 17/15m LPF on the ANAN PA board instead, to increase the power output on 12m on the ANAN PA.  

This LPF switch point change for 12m Tx operation using the 17/15m LPF on the ANAN PA is already in Angelia_v2.6 firmware and later Angelia firmware; Abhi’s post simply put that change into the Hermes code for use when the Hermes board is used with the ANAN PA.  

Note that the change is not appropriate generally for Hermes (or Angelia, for that matter).  In particular,  if you use a TAPR Alex LPF filter board with your Hermes board (or Angelia board) then the original un-modified LPF switch-point firmware is better suited for you.  The modified 12m Tx LPF switchpoint is only appropriate if you are using a Hermes board (or Angelia board) with the ANAN PA, as you would be doing if you own an ANAN-100 (or an ANAN-100D), for example.  

The ANAN PA contains LPFs that are very similar to the TAPR Alex LPFs;  however, it is my understanding that it was found that the impedance match of the LPF filter in the ANAN PA for 15/17m LPF better matched the operation of the amplifier when operating on 12m than did the 10/12m LPF on the ANAN PA, thus this is what has prompted the change in LPF switching code that is used with boards using the ANAN PA; simply put, the change results in higher output power for the ANAN PA on 12m.  

I hope my interpretation of the events is accurate and that my explanation improves up your understanding of the modified Hermes code that Abhi provided.  

73, Joe K5SO


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