<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div><span>Diode replacement for 1N191 - a silicon (e.g. 1N270) would probably do fine - you would lose a bit of output on the low end but it is only 'relative' power. A schottky such as the 1N5711 (readily available at Mouser for $0.50) would give the low forward voltage - reverse breakdown voltage is 70V but I don't think that is a problem. See next</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: times new roman,new york,times,serif; background-color: transparent; font-style: normal;"><br><span></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: times new roman,new york,times,serif; background-color: transparent; font-style: normal;"><span>The voltage problem is not a problem - there is a honking resistor <span style="text-decoration: underline;">divider</span><span> (R24 and
R26) from the RF output to the diode. So crank a 68:1 (68K/1K) voltage reduction in there and your 70V breakdown is now 4,760 volts (i.e. 70 * 68) which is obviously not a problem. </span></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: times new roman,new york,times,serif; background-color: transparent; font-style: normal;"><br><span></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: times new roman,new york,times,serif; background-color: transparent; font-style: normal;"><span>Also 1N34A will work with a Vbr of 35V (35*68 = 2,380V) and they seem to be readily available.</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: times new roman,new york,times,serif; background-color: transparent; font-style: normal;"><br><span></span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: times new roman,new york,times,serif; background-color: transparent;
font-style: normal;"><span>73 and happy DX</span></div><div style="color: rgb(0, 0, 0); font-size: 16px; font-family: times new roman,new york,times,serif; background-color: transparent; font-style: normal;"><span>Bob Groh, WA2CKY<br></span></div><div><br></div> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div dir="ltr"> <hr size="1"> <font face="Arial" size="2"> <b><span style="font-weight:bold;">From:</span></b> Alexander N. Gerli <ac1wye@gmail.com><br> <b><span style="font-weight: bold;">To:</span></b> heathkit@mailman.qth.net; "heath@puck.nether.net" <heath@puck.nether.net> <br> <b><span style="font-weight: bold;">Sent:</span></b> Tuesday, January 21, 2014 9:15 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> [Heath] HL-2200 amp problem<br> </font> </div> <div class="y_msg_container"><br>
<div id="yiv1943203147"><div dir="ltr"><div class="yiv1943203147gmail_default" style="font-size:large;color:rgb(0,0,255);">Hi, everyone,<br><br></div><div class="yiv1943203147gmail_default" style="font-size:large;color:rgb(0,0,255);">My HL-2200 is running fine except for one small thing: the Relative Power positions on the Meter switch don't read.<br>
<br></div><div class="yiv1943203147gmail_default" style="font-size:large;color:rgb(0,0,255);">I've checked the parts in the chain, and I'll bet the 1N191 Germanium diode is shot. All the other parts in the resistive divider chain check out, both at the output SO-239 terminal strip and also on the terminal strip below the multimeter.<br>
</div><div class="yiv1943203147gmail_default" style="font-size:large;color:rgb(0,0,255);">Gotta be that diode.<br><br></div><div class="yiv1943203147gmail_default" style="font-size:large;color:rgb(0,0,255);">Problem is...1N191s aren't available any more, and they're Germanium which makes them a bit fragile for reverse voltage peaks. The '191 has a PRV of 90V which seems awfully low, even given the 68K ohm 2W sampling resistor ahead of it going to the SO-239.<br>
<br></div><div class="yiv1943203147gmail_default" style="font-size:large;color:rgb(0,0,255);">What to do? Does anyone on the List have any suggestions for a good substitute which is readily available? I have some 1N270s, but they're Silicon and perhaps not as sensitive as those Germaniums. Seems to me that I should use a diode with a PRV of more than just 90V!<br>
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Thanks for your help, as always!</div><br><br></span></font></span></div><span style="font-family:arial, helvetica, sans-serif;"><font size="4"><span style="color:rgb(0,0,255);"><div class="yiv1943203147gmail_default" style="font-size:large;color:rgb(0,0,255);display:inline;">
73, Sandy AC1Y</div><br><br>Alexander N. Gerli, Sr.<br></span></font></span></div><span style="font-family:arial, helvetica, sans-serif;"><font size="4"><span style="color:rgb(0,0,255);">548 Allred Mill Road<br></span></font></span></div>
<span style="font-family:arial, helvetica, sans-serif;"><font size="4"><span style="color:rgb(0,0,255);">Mount Airy, NC 27030-2202<br><br></span></font></span></div><span style="font-family:arial, helvetica, sans-serif;"><font size="4"><span style="color:rgb(0,0,255);">Scotsmen walk about 900 miles each year.<br>
</span></font></span></div><span style="font-family:arial, helvetica, sans-serif;"><font size="4"><span style="color:rgb(0,0,255);">A Scotsman drinks around 45 gallons of Whisky a year.<br></span></font></span></div><font size="4"><font size="4"><font size="4"><font size="4"><font size="4"><font size="4"><font size="4"><font size="4"><font size="4"><font size="4"><font size="4"><font size="4"><span style="font-family:arial, helvetica, sans-serif;"><span style="color:rgb(0,0,255);">Scotsmen get about 20 Miles Per Gallon.</span></span><br>
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