<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div>Hi Dan,</div><div>I have been meaning to get back here and update the post, thanks for the reminder. Yes, the resistor change did the trick. The bias adjustments fell right in. I am driving the Munin lll to over 100 watts on all bands with my Orion ll board. The exception is 6 meters (about 80 watts). I suspect that if I did a better job on L4 I could get the power on 6 up to par. I have some 50 ohm formable cable, the kind that looks like it has a soldered shield for the outer layer. It is small enough to fit four of them in the binocular core. I may try building a new L4 with the four coax method and throw it on the VNA to see if it performs any better up to 50MHZ. I am in no hurry as I have no 6 meter antenna at the moment. I am very pleased with the Munin lll amp. My thanks to all involved. If any other builders need me to make measurements or whatever to assist troubleshooting, just holler.</div><div><br></div><div>73,</div><div><br></div><div>Bob. K6GGO</div><div><br>On Mar 9, 2018, at 9:48 AM, Dan Mitchell <<a href="mailto:danmitchell387@gmail.com">danmitchell387@gmail.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Bob;<div>Were you able to get the idle current where you wanted it after changing the resistors?</div><div>73,</div><div>Dan, W0IQ</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Mar 2, 2018 at 9:22 AM, rwfish <span dir="ltr"><<a href="mailto:rwfish56@gmail.com" target="_blank">rwfish56@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><span class="">***** High Performance Software Defined Radio Discussion List *****<br>
<br>
</span>Hi Kjell,<br>
Ah, the world makes sense again. I will change out the resistors and soldier on. I almost always emerge on the other side of these obstacles a little wiser. I will update when I get this thing working.<br>
<span class="im HOEnZb"><br>
Thanks & 73,<br>
<br>
Bob. K6GGO<br>
<br>
</span><div class="HOEnZb"><div class="h5">> On Mar 2, 2018, at 12:48 AM, Kjell Karlsen <<a href="mailto:la2ni@online.no">la2ni@online.no</a>> wrote:<br>
><br>
> ***** High Performance Software Defined Radio Discussion List *****<br>
><br>
> Hi Bob.<br>
><br>
> The problem is that when I built the first prototype of Munin III, I used a pair of RD100HHF1 from an old batch of transistors that have a low Vth (Gate treshold voltage) This voltage can be from 1,5-4,5V (see the date sheet page 1). If the Vth is in the upper part of the voltage range, R9 and R10 (1,5K) must be replaced with 2,2K resistors.<br>
><br>
> I have received reports from 2 Hams that have had this problem. It seems as the transistors delivered today have higher Vth than before.<br>
><br>
> Sorry for the problem but there has not been any issues before as far as I know.<br>
><br>
> 73, Kjell, LA2NI<br>
><br>
><br>
><br>
><br>
> På Fri, 02 Mar 2018 06:33:26 +0100, skrev rwfish <<a href="mailto:rwfish56@gmail.com">rwfish56@gmail.com</a>>:<br>
><br>
>> ***** High Performance Software Defined Radio Discussion List *****<br>
>><br>
>> Hello,<br>
>> I recently finished building a Munin lll amplifier. I am having trouble setting up the bias for T1 and T2. I assume that the devices should be biased at 1A each as they are in the Munin 2. I can’t seem to get the the current to 1A on either device with the associated pot. I am measuring the total current to the board with a DMM in series with the +13.8 line. I thought perhaps the 10K thermistor circuit was loading down the bias circuit so I lifted one leg of the thermistor. This did raise the current somewhat however still not enough. I also have a bit of an imbalance between the devices (ie different gate voltage to get same source/drain current). The current maxes out at 800ma on one device and 400ma on the other. I then lifted the gate connection on each device and measured the range of the bias voltage. Both bias channels are identical at 2.5 to 4.3vdc. I then used an external dc power supply to bias the Mosfets. I was able to swing both mosfets all the way up to 5 or 6 amps or higher independantly with an external bias supply, but I do have to go slightly higher in voltage than 4.3v. Maybe 5v or so. I am stumped, any ideas?<br>
>><br>
>> Sorry for the long winded post but I wanted to include most of the details.<br>
>><br>
>> Thanks & 73,<br>
>><br>
>> Bob. K6GGO<br>
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