[Amps] Noisy relay

[Tim Duffy]

Thanks Jim

My concern is with the diode(s) across the relay(s) coil (or Zener diode combo) does it affect the timing on the front end closure of the relays?

As in TX delay settings? So when the relays "settle" before RF is applied?

Three relays involved. Input, output and bias

73
Tim K3LR

-----Original Message-----
From: MU 4CX250B [mailto:4cx250b at miamioh.edu] 
Sent: Monday, December 12, 2022 1:48 AM
To: Tim Duffy
Cc: Steve London; amps at contesting.com
Subject: Re: [Amps] Noisy relay

Hi Tim, Yes a clamping diode will slow down the release time of a dc
relay. The time constant (release time) is approximately L/R, where L
is the relay coil inductance and R is the coil resistance. If the
release time is objectionable, it can be shortened by adding a zener
diode (typically with a zener voltage roughly equal to the power
supply voltage in series with the clamping diode.
73,
Jim W8ZR
Sent from my iPhone

> On Dec 11, 2022, at 7:00 PM, Tim Duffy <k3lr at k3lr.com> wrote:
>
> Hello Jim
>
> Does that clamping diode across the coil affect the TX key up delay time? As in "slow it down"?
>
> 73
> Tim K3LR
>
> -----Original Message-----
> From: Amps [mailto:amps-bounces at contesting.com] On Behalf Of MU 4CX250B
> Sent: Sunday, December 11, 2022 5:49 PM
> To: Steve London
> Cc: amps at contesting.com
> Subject: Re: [Amps] Noisy relay
>
> Steve, you might be hearing the induced voltage kick caused by the
> inductance of the coil. Try putting a clamping diode. A small signal
> diode like a 1n914 will work fine,
> 73,
> Jim w8zr
>
>
> Sent from my iPhone
>
>> On Dec 11, 2022, at 9:39 AM, Steve London <n2icarrl at gmail.com> wrote:
>>
>> Commander HF-2500..
>>
>> Every time the T/R relay goes back to receive, I'm getting a pretty big RF
>> spike that I can hear in the receiver. This has nothing to do with the
>> transceiver hot switching or RF stored in the tank circuit. I can reproduce
>> it just by cycling the T/R relay in the amp with a separate cable, not
>> connected to the transceiver, and not transmitting.
>>
>> Suggestions ?
>>
>> 73,
>> Steve, N2IC
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