MIRAGE B215 vhf amp help

[VK4NWH]

, I am looking for a manual for a b215 vhf amp, does anyone have a manual that they can copy and email or post? I will pay any costs involved. Mine is a 1985 model 2 watts in and 150 watts out. Mirage have nothing at all. My amp has 50 watts fm and nothing ssb but was working fine till something went off track. Any ideas or help is greatful. Thanks.

Wayne VK4NWH
amateur_radio@westnet.com

[KC8VWM]

Check the switches, relay circuits, measure all resistor values (may be an open resistor) Some of these amplifiers have built in shut down protection circuitry which may have gone awry. Measure the voltages present on the power transistors and instead of using a schematic, download a spec sheet for the output transistors in question and compare the spec sheet voltage information with your readings. Rule out if it's the power transitors at fault or if the other circuits supplying current to the output transitors are at fault etc..

Also be sure to check the obvious but not so obvious things like coax connections, (especially the ground side of things) broken or loose switch wiring, be suspicious of brown marks or solder corrosion occuring on the circuit board etc..

Good luck

[KE7TBB]

www.mirageamp.com/man/pdf/B-215-G.pdf
your welcome

just a google search brought it up

[WB2WIK]

Originally Posted by KE7TBB

www.mirageamp.com/man/pdf/B-215-G.pdf
your welcome

just a google search brought it up

Didn't work.

[VK4NWH]

thanks WB2WIK and KE7TBB i seen that but thats the G model mine is the 1985 b215 not b215-G but thanks for ur help.

[VK4NWH]

Thanks Charles KC8VWM i did check the output transistors and had voltage to them all but ill check again and also so through your thoughts also. it worked fine while i was txing and i turned it off to compare signals with other hams and when i turned it on again ... nothing. But ill start again with your ideas. i already replaced the mps-a13 switching transistors.

[N6OSB]

Try this link:
http://www.mirageamp.com/man/pdf/B-215-G.pdf

[VK4NWH]

i seen that but thats the G model mine is the 1985 b215 not b215-G but thanks for ur help. cheers.

[KC8VWM]

It's just another thought but you indicated it makes power on FM but not on SSB. This suggests the RF sensing circuitry is probably working (switching to TX, ok) however, I am still somewhat curious if connecting an external switch and try TX'ing the amp with an external keyer will somehow produce different results?

Also thinking that while FM is present on output but no SSB operation may suggest a voltage issue in the output transistors bias supply circuit? But like yourself, I'm not looking at a schematic either. I would probably start by measuring resistor values in proximity to the transistors to see if one has opened somewhere. Keep in mind although you have the correct voltages powering the power transistors, there is still a chance one was fried. I have to admit though, I'm kind of surprised the fuse didn't open in the process. Not sure what type or transistors they are exactly but it may be possible to measure continuity or resistance from them using a VOM and compare the readings of each transistor against one other for the purpose of conducting a comparative analysis. One transistor may read differently than all the others scenario. Perhaps you had a power spike of some sort?

I realize this is sort of a shotgun approach, but i'll keep thinking and I'm sure others will chime in with their own thoughts. Maybe someone will even post a good schematic so we can all sit on here and have a good gawk at it.

My Best,

[VK4NWH]

well charles im living in hope at the moment but your ideas are certainly some good points to start looking at.