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MMS 70k - 70620B opt001 hardware problem

Question asked by f5bqp on Aug 28, 2014
Hi,

I've a problem with my 70620B opt001 100kHz ~ 26GHz preamplifier, the gain is quasi null.
I've tested separately the internal RF parts:
The Low Band amplifier is ok
The High Band amplifier is ok ~ 30db of gain
The input transfer switch is ok
Remain the two RF Switches (pin switches) reference *5086-7857*, and my interrogation are around them:
These two RF Sw are used to switch the Low and High band during a sweep.
1) I verified the voltage on their command line (only one wire per pin sw) and I find approximatively +14V in Low band and -15V in High band (or reverse I dont remember)
2) One pin switch has approx 10db attenuation, the one at the input of the two amps (LB & HB)
3) One pin switch has approx 20db attenuation, the one at the output of the two amps (LB & HB)

I'm pretty certain the problem is coming from these two solid state RF switches and my interrogations are:
a) What are the precise command voltages these RF switches should have when working properly?
b) Which attenation these switches shoud have ? What are their specs?

I'm asking these questions because there are two possibilities: or the command volatage are bad, then the problem is a logic command/power supply failure, or the switches are dead and I'll need to find two of these *5086-7857* 

If you can help to give me the specs of these switches I'll appreciate very much to dertermine if I'm wrong or not into my investigation.
Then how to get these parts or a replacement?

Pierre-Francois, F5BQP  

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