I will have soon, a new to me, GRC-19 that is in working order. <span style="border-color:rgb(0,0,0);color:rgb(0,0,0)">It will be powered using a PP-1104. I</span> would appreciate any advice you have.<div dir="auto"><br></div><div dir="auto">I realize this is a communications audio quality transmitter but I understand there are modifications that can be made to make it have a broader frequency response.<br></div><div dir="auto"><br></div><div dir="auto">What microphone should be used? Are there circuit changes that can be made to broaden the modulation frequency response? (I’ve done an unsuccessful search on Google.)</div><div dir="auto"><br></div><div dir="auto">Thanks in advance for any pointers on the successful operation of this rig on AM 75 meters band.</div><div dir="auto"><br></div><div dir="auto">Mack</div><div dir="auto">W4AX</div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><font size="4" style="background-color:rgb(255,255,255)" color="#0000ff"><br></font></div><div><font size="4" style="background-color:rgb(255,255,255)" color="#0000ff">73, </font></div><div><font size="4" style="background-color:rgb(255,255,255)" color="#0000ff"><br></font></div><div><font size="4" style="background-color:rgb(255,255,255)" color="#0000ff">Mack</font></div><div><font size="4" style="background-color:rgb(255,255,255)" color="#0000ff">W4AX</font></div><div><a href="https://www.qrz.com/db/W4AX" target="_blank">https://www.qrz.com/db/W4AX</a><font size="4" style="background-color:rgb(255,255,255)" color="#0000ff"><br></font></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div>