[hpsdr] Munin works finally

[Berndt Josef Wulf]

G'day Kjell,

many thanks for your inside.

Do we have a part number for the 10K NTC resistor? I couldn't find the
NTC listed in the BOM. Will try to get the parts through a local
supplier (Element14, RS-Component etc).

73, Berndt
VK5ABN




On Wed, 2013-12-18 at 14:20 +0100, Kjell Karlsen wrote:
> Hi Berndt.
> 
> I have also seen the increase of bias current when the temperature rise.  s, 
> Therefore I included the stabilizing circuit. But anyway, I always us a  
> cooling fan. Remember that the idling power is >40W.(13,8V X 3A=41,4W) At  
> 100W CW, the power consumption is ca. 250W and at least 150W is heat.
> 
> With a temperature controlled cooling fan, I believe Munin can be used for  
> very long periods at full power on RTTY. But PSK31 requires that the PA  
> always is in its linear range so running more than 25-30W is not  
> recommended. This is true for all 100W transceivers.
> 
> 73, Kjell
> 
> 
> 
> 
> 
> På Wed, 18 Dec 2013 13:05:09 +0100, skrev Berndt Josef Wulf  
> <wulf at ping.net.au>:
> 
> > ***** High Performance Software Defined Radio Discussion List *****
> >
> > G'day Tony,
> >
> > I've just completed building my amplifier and can confirm your
> > observation regarding the instability of the bias current. The circuitry
> > for Munin2 implements temperature compensation using a NTC resistor and
> > my plan is to modify my amplifier using this circuit.
> >
> > The heatsink supplied with the kit gets fairly warm when in idle mode,
> > e.g. PTT enabled with input and output terminated into 50 Ohms, which
> > makes me think that it may require a cooling fan for normal operation.
> >
> > This raises the question about Munin's capability of being operated at
> > 100% duty cycle, e.g. PSK31, RTTY etc. for prolonged time? Is anyone
> > operating Munin in these modes and what is your experience?
> >
> > I've yet to test my amplifier with RF applied, so I can't comment on
> > this.
> >
> > 73, Berndt
> > VK5ABN
> >
> > [...]
> >>
> >> Further, what I experienced the bias voltage shifts with the
> >> temperature rise that might result in instability of the power output
> >> so something temperature compensated bias circuitry if incorporated
> >> will enhance the efficiency of the circuit.
> >>
> >> Of course, my present worry is C25,C26,C27
> >>
> >>
> >> 73s
> >> Tony
> >
> >
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> 
> 



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