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CDM1550 - switchable 3dB pad - does this exist?

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g8tzl2004
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CDM1550 - switchable 3dB pad - does this exist?

Postby g8tzl2004 » Wed Aug 02, 2017 10:54 am

Does the CDM1250/1550 and GM360/380 series have a switchable 3dB attenuator pad?

The service manual states the following:

" A switchable 3dB pad (R3022, R3024, R3016, and R3018) controlled via Line FECNTL_2 and Q3021 stabilizes the output impedance and intermodulation performance".

However, I can find no mention in the CPS about a switchable attenuator pad option.

So is it possible to switch in an attenuator in a CDM radio? Maybe this is used when a CDM is used to build a repeater??

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jackhackett
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Re: CDM1550 - switchable 3dB pad - does this exist?

Postby jackhackett » Wed Aug 02, 2017 3:38 pm

However, I can find no mention in the CPS about a switchable attenuator pad option.


Have you looked in the Tuner software?

g8tzl2004
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Re: CDM1550 - switchable 3dB pad - does this exist?

Postby g8tzl2004 » Thu Aug 03, 2017 12:55 pm

I checked out the tuner section but could not find anything relating to a 3dB attenuator.

Have you ever come across this feature?

Do you have to have certain accessory socket pins enabled to view repeater data?

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kcbooboo
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Re: CDM1550 - switchable 3dB pad - does this exist?

Postby kcbooboo » Fri Aug 04, 2017 4:34 am

Could it be a per-channel "Local/DX" setting, like GM300s have?

Bob M.

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jackhackett
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Re: CDM1550 - switchable 3dB pad - does this exist?

Postby jackhackett » Fri Aug 04, 2017 5:17 am

I don't believe they have a local/dx setting.

I've been working with CDMs for a long time, never came across anything about an attenuator and never had any need for it. My advice would be don't worry about it, it's probably something internal that you have no control over.


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