Re: [Elecraft] ATU and Bandpass Filter

2017-06-26 Thread Erik Basilier
ssage- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob McGraw K4TAX Sent: Friday, June 23, 2017 7:47 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] ATU and Bandpass Filter If one chooses to use band pass filters then one should anticipate using an

Re: [Elecraft] ATU and Bandpass Filter

2017-06-23 Thread Bob McGraw K4TAX
If one chooses to use band pass filters then one should anticipate using an external antenna tuner as well. This of course depends largely on the antenna and the impedance of the antenna at a given frequency.If one is using resonant antennas with a reasonably close 50 ohm impedance then a

Re: [Elecraft] ATU and Bandpass Filter

2017-06-23 Thread donovanf
20 meters with no trace on interference. 73 Frank W3LPL - Original Message - From: "Don Wilhelm" To: elecraft@mailman.qth.net Sent: Saturday, June 24, 2017 12:03:29 AM Subject: Re: [Elecraft] ATU and Bandpass Filter What Matt said is true. However, if your a

Re: [Elecraft] ATU and Bandpass Filter

2017-06-23 Thread Don Wilhelm
Lane, Yes, you cannot do that. We are only discussing the need for the filter to have a 50 ohm non-reactive load. So if you are using a bandpass filter designed for a 50 ohm load (most are), then you need to use resonant antennas. What I was saying is that slight variations from a 50 ohm load

Re: [Elecraft] ATU and Bandpass Filter

2017-06-23 Thread Lane
I think I'm missing something here. I'm not sure I understand putting the ATU after the filter since the ATU is internal. How does one put it after the external BP filter? On Fri, Jun 23, 2017 at 7:03 PM, Don Wilhelm wrote: > What Matt said is true. However, if your antennas are close to resonan

Re: [Elecraft] ATU and Bandpass Filter

2017-06-23 Thread Don Wilhelm
What Matt said is true. However, if your antennas are close to resonance, go ahead and use the ATU to "touch up" the tuning. If you are trying to use a multiband antenna such as a G5RV and such, you might as well forget the advantage of the bandpass filter. Our local club discovered that mul

Re: [Elecraft] ATU and Bandpass Filter

2017-06-23 Thread Matt Maguire
The problem is that the filter is designed to work with a 50 ohm characteristic impedance (ie. with a 1:1 VSWR). This means you need to put ATU *after* the filter, not before, otherwise the filter will not work properly. 73 de Matt VK2RQ > On 23 Jun 2017, at 1:13 pm, Lane > wrote: > > A ques

[Elecraft] ATU and Bandpass Filter

2017-06-22 Thread Lane
A question about the K2. Taking it to the club for FD and I have a bandpass filter (CF-20) which says "Never use radio's internal tuner with filter." I have the internal ATU installed. Is there a way to bypass that? Or should I just use the "main antenna" jack (manual says never use if ATU install