On 10/30/2010 6:42 PM, Jim Barber wrote:
> Aha - Now that makes sense.
>
> I wonder if Orr possibly just assumed the noise was from the diodes? At
> this point we probably won't ever know.
>
In the old days of rectifier tubes they could make a LOT of noise
73
Roger (K8RI)
> In most cases these days (and certainly in this case) the tube would be
> biased off when in RX or standby, so no problem, then.
>
> 73,
> Jim N7CXI
>
> On 10/30/2010 3:29 PM, Fuqua, Bill L wrote:
>> The broadband noise is not due to the current thru the rectifieres but the
>> shot noise the transmitting tube. If the tube is not biased off during
>> receive and you are using an electronic switch or the receiver is not
>> entirely decoupled from the output of the transmitter you will get broad
>> band noise generated by the random arrival of electrons on the plate of the
>> tube. I once had this problem with my EF Johnson Challenger transmitter
>> when I was using separte transmitting and receiving antenns. It had not
>> solid state diiodes in it at all. Took a while to figure it out, I was only
>> a teenager at the time.
>> 73
>> Bill wa4lav
>>
>> ________________________________________
>> From: amps-bounces@contesting.com [amps-bounces@contesting.com] On Behalf Of
>> Jim Barber [audioguy@charter.net]
>> Sent: Saturday, October 30, 2010 4:32 PM
>> To: AMPS
>> Subject: [Amps] HV rectifier strings - to bypass or not?
>>
>> I'm getting ready to lay out the HV rectifier board for my YC156
>> project, and it occurs to me to wonder if anyone has ever really heard
>> HV rectifier "white noise" in the receiver? It would be simpler to
>> forget about the per-diode bypass caps and just bypass the output as it
>> leaves the board. The supply will be housed in a separate cabinet from
>> the RF deck, but connected of course with bypassed leads for HV, (SHV
>> connectors) 110VAC and control signals.
>>
>> My current intent is to use 8 6A10 diodes per leg. The transformer is a
>> 3KV, 2A CCS Peter Dahl and the filter is 32uF by means of two new 16uF
>> 7500V oil-filled caps from Henry Radio via eBay.
>>
>> Opinions?
>>
>> Thanks,
>> Jim N7CXI
>>
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>> http://lists.contesting.com/mailman/listinfo/amps
>>
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