Re: Harmonics

Scott McDonald

My last shipment, post their move, got here in two weeks, so hopefully things are humming again.  The filter switching kit is well worth the effort and price.  I’m using them for bandpass filters in a receiver, but will probably divert one to the UBITX for a few favorite bands while the dust settles.

The order before was pretty slow, but an email got an immediate answer and things expedited a bit.

73 Scott ka9p

On Aug 10, 2018, at 10:29 PM, RICHARD <k6kwq@...> wrote:

I have been waiting for over a month now for an order from QRP labs.  All shipments come from Turkey.  Great products but shipping time is not so good.



Sent from Mail for Windows 10


From: <> on behalf of Michael Babineau <mbabineau.ve3wmb@...>
Sent: Friday, August 10, 2018 7:14:56 PM
Subject: Re: [BITX20] Harmonics
Kees : 

I am thinking that since I have a pile of Arduino Nanos that I got for $2, even though it is overkill,
I may use one of those to sample TXA/TXB and TXC and  switch the additional filters. 

My plan is to use a QRP Labs relay switched LPF kit since it is already exists, is pretty much exactly what I am looking for
and only costs $16 (minus the LP filters). The individual plug in LPF kits are $US4.95 each.

It will take 5 LP filters, we only need 4, but I already have an additional one for 160m that I will figure out how to switch in as well. 
I was originally planning to do that somehow anyway. 

I don't plan to disable the existing uBITX LPFs as I don't care about the additional current draw or 
the fraction of a dB insertion loss. The existing filters are doing something, just not enough, so adding cascading LP filters
should cover all of the bases with room to spare, except for the SSB spurs on the high bands which will be a tougher nut
to crack. 


Michael VE3WMB 

P.S. I am a software guy, not a hardware guy, so it makes sense to me to use a microprocessor to solve a hardware problem ;-) 

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