[NLRS] Mirage Amplifier

[John P. Toscano]

Scott:

A (relatively) easy way to test Clare's suggestion:
   Get a 20 watt 6 dB 50 ohm attenuator and try driving the amp with 20 
watts from your 2M rig.  Or get a 10 watt 3 dB 50 ohm attenuator and try 
driving the amp with 10 watts from the 2M rig.  The idea is that if the 
output impedance isn't 50 ohms, it will come closer to looking like 50 
ohms with the attenuator in series. The more attenuation, the better the 
attenuator "hides" the incorrect output impedance it is being driven 
with, but of course then the higher the power rating and therefore the 
size and cost of the attenuator, and the more drive output power you 
need to waste in the attenuator as heat.

Hope that helps a bit. (Sure seems easier and cheaper than digging into 
the circuitry and replacing final transistors if they happen to not be 
blown.)

73 and GL from W0JT, John

jarvis at jarviscomputer.com wrote:
> 
> Hi Scott,
> 
> I have a B2516G.   This unit is extremely sensitive to input impedance.  
> If there is any mismatch on the input side then there is little or no
> output drive.
> 
> 73 Clare
> de K0NY
> 
>> Anyone in NLRS land have a Mirage B215 or similar?  I think there was also
>> a 1015?  This is the 2w input 150w output model.  I need to find a
>> schematic or someone that knows what commonly goes wrong on these.  This
>> one has no output with 2-5w of drive, the manual states a max of 5w drive.
>>
>> Can I remove the first stage of the amp to increase the input level, and
>> if so how much could I then drive the amp with?  I'm assuming that the
>> finals are kaput on this one.  I haven't taken it apart to further
>> diagnose yet, all I know so far is it powers on and the preamp works, but
>> it doesn't have any output.
>>
>> 73,
>>
>> Scott  KB0NLY