[time-nuts] 3325A attenuators
Normand Martel
martelno at yahoo.com
Wed Feb 21 04:06:20 UTC 2007
Do you hear the relays working when you change the
signal level?
If yes, and that's probably the case, i definitely
suspect burned-out attenuator resistors/modules
(HIGHLY probably due to excessive reverse power
(Signal generator directly plugged to a transceiver
which has been accidently keyed)).
If your attenuators use resistors, you may try to
substitute nearest 1% precision resistors.
Theorical values for a 50 ohm system:
10dB attenuator:
Pi attenuator: Series resistor: 71.151246 ohm
Parallel resistors: 96.247531 ohm
T attenuator: Parallel resistor: 35.136419 ohm
Series resistors: 25.974692 ohm
20dB attenuator:
Pi attenuator: Series resistor: 247.5 ohm
Parallel resistors: 61.111111 ohm
T attenuator: Parallel resistor: 10.10101 ohm
Series resistors: 40.909091 ohm
40dB attenuator:
Pi attenuator: Series resistor: 2499.75 ohm
Parallel resistors: 51.010101 ohm
T attenuator: Parallel resistor: 1.001 ohm
Series resistors: 49.0099 ohm
For 40dB, i suggest to use two cascaded 20dB units
instead of a single 40dB unit (values much closer to
50 ohms for the single resistor)
73 de Normand VE2UM
Montreal, Qc. Canada
--- "Paul S. Linsay" <linsay at comcast.net> wrote:
> Hi,
>
> I have a 3325A and the amplitude attenuators are not
> working. I
> opened it up and it has sealed black relays, not the
> unsealed ones
> mentioned in the maintenance manual. When I run the
> front panel self-
> test everything passes. Any suggestions on what to
> do next?
>
> Thanks for your help,
>
> Paul--
>
> _______________________________________________
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> time-nuts at febo.com
>
https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
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