[hpsdr] Munin works finally

[Kjell Karlsen]

Hi Berndt.

I have also seen the increase of bias current when the temperature rise.  
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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