[Amps] Real time tests to see if an RF transformer is

[Jim Brown]

It depends on WHY there is dissipation.  Is the filter out of alignment 
(likely component failure/changing value) ? That sets up a mismatch to 
the line from the exciter, and may also increase circulating currents in 
the filter. That can result in too much of the fundamental being 
dissipated, overheating the filter more. Failure might have been caused 
by driving the amp on the wrong band.

When the driver (transceiver) is mismatched to its load, most solid 
state output stages will throttle back to protect themselves. When this 
happens, the transceiver produces less power.

73, Jim K9YC

On Fri,6/16/2017 9:57 AM, Jim Thomson wrote:
> Date: Fri, 16 Jun 2017 12:44:43 +0100
> From: Chris Wilson <chris at chriswilson.tv>
> To: amps at contesting.com
> Subject: Re: [Amps] Real time tests to see if an RF transformer is
> saturating?
>
>
> <Is heat produced in an LPF indicative of wasted energy to the antenna,
> <or  is  it just the function of dissipating the unwanted harmonics and
> <will be produced by any filter designed to remove them?
>
>
>> Chris.
> ###  AFAIK, if the LPF heats up, its components are not sized correctly to handle the
> fundamental.   The harmonics are reflected back towards the PA.  The harmonics are
> not absorbed by the LPF, nor are they routed through to.... ground.  But here we  are talking about
> 136 khz... so the cut off would have to be well below   272 khz, but higher than 136 khz.  Is that
> even doable ?   How much harmonic suppression is required ?  How much attenuation is
> readily achievable, in a practical LPF circuit.   I can well imagine a LPF  with a cut off of say
> 150 khz, having component values that are bizzare.
>
> Jim VE7RF
>
>
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