[Amps] caps across rectifier diodes

[Fuqua, Bill L]

Most HV rectifiers' switching speeds are too slow to rectify RF at ham frequencies. Reverse recovery time is usually on the order of microseconds. 
That is why they are some times used in place of PIN diodes in cheap RF switches and attenuators. 
Also as meter protection diodes. If you use fast  signal or switching diodes across meters in RF amplifiers in some cases the meters will actually swing the
wrong way because they do rectify the RF.
  So these slow switching speed HV diodes can modulate RF signals but not rectify them. They also make for cheap varicap diodes for the same reason.

73
Bill wa4lav

________________________________________
From: amps-bounces at contesting.com [amps-bounces at contesting.com] On Behalf Of Jan Erik Holm [sm2ekm at telia.com]
Sent: Wednesday, March 04, 2009 12:11 AM
Cc: amps at contesting.com
Subject: Re: [Amps] caps across rectifier diodes

yeah goes to show what happens if you put caps
across the diodes.

/ SM2EKM
----------
Carl wrote:
> Is Emtron even in business any longer?  Their feedback is mighty poor.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Doug Renwick" <ve5ra at sasktel.net>
> To: <amps at contesting.com>; <rfamplifiers at yahoogroups.com>
> Sent: Tuesday, March 03, 2009 11:13 AM
> Subject: Re: [Amps] caps across rectifier diodes
>
>
>> I took a look at my Emtron amp ps board and they also add a cap across
>> the P600M diodes.  Thus several amp ps manufactures feel it is a
>> requirement to place a cap across each diode.
>>
>> Doug
>>
>> The train doesn't stop here anymore.
>>
>> -----Original Message-----
>>
>> Sorry? ... on the contrary.
>> I believe the answer from the archives is "capacitors prevent RF from
>> being rectified in the diodes, and generating harmonics."
>>
>> Doug
>>
>> The train doesn't stop here anymore.
>>


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