[Elecraft] BPF Bypass

[Devin Butterfield]

Hi Brian,

Thanks for the input. Yeah I know the bypass is not ideal (garbage, etc.), but for ALE scanning it would be better than hammering on the relays.

It is possible to select the bypass of the BPFs, as the hardware was clearly designed to support this. But the docs don’t explain how to get this to happen.

I would greatly appreciate if anyone with knowledge of the KX3 could shed some light on what mode the software needs to be in to get the BPF bypass to happen.

Thanks!
—
73s, Devin / KD6DRS

> On Mar 9, 2017, at 4:24 PM, brian <alsopb at comcast.net> wrote:
> 
> Sorry, I don't have answer on the bypass.
> 
> However, bypassing BPF's may result in lots of received out of band garbage.  I have to think they would be in the RX path too.
> 
> You have discovered one big downside of using commercial ham rigs for ALE.  One can quickly destroy bandpass filter relays with full 24/7 ALE.
> 
> 
> On 3/9/2017 22:07 PM, Devin Butterfield wrote:
>> Hi,
>> 
>> I have a KX3 and so far I’m very pleased. Very nice design and good build.
>> 
>> I would like to use this radio for ALE, which requires cross-band scanning. This mode is used only for initial detection. If I use the KX3 as is, when changing bands I can clearly hear relays switching, which I think is in the BPF circuit (please correct me if I’m wrong).
>> 
>> Looking at the schematic it appears the BPF can be bypassed by asserting the BPF_BYPASS signal, but it isn’t clear from the user manual or CAT programming manual what mode in the KX3 achieves this effect.
>> 
>> Any ideas how to get the KX3 to bypass the BPFs?
>> 
>> Thanks, Devin / KD6DRS
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