When you buy RA6LBS filters each comes with a tracing by a spectrum
analyzer showing the exact filter characteristics. On each of these that I
own the tracing matches the Rigol with tracking generator. They really work
well. I have a complete set of 500 watt filters from RA6LBS. They are sold
by
On 7/27/2021 12:53 PM, Morgan Bailey wrote:
80 to 100 dB band to band attenuation is necessary for a contest station.
That depends a LOT on the radios and the amps.
Reviewing Contest University the RA6LBS talk from a few years ago is the
basis for this decision. He probably has the most
David
I purchased blank PCBs from VA6AM along with the torroids with a view to
building a switched filter set.
Still on my list of “want to do” and my motivation was driven by space
reduction in my portable SO2R project.
However I’ve somewhat learnt the hard way to be honest with myself
Thanks all for the great advice and the further reading.
In my specific case of K3S + KPA500 + KAT500, is there no room to reduce the
high performance W3NQM filters?
I understand common mode filters and have made good versions of these from K9YC
cookbook. They remain in circuit all the time,
Bird makes a very good bandpass filter for the SDR radio you are
speaking of... It gets rid of ALL phase noise on all bands at once.
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On
80 to 100 dB band to band attenuation is necessary for a contest station.
Reviewing Contest University the RA6LBS talk from a few years ago is the
basis for this decision. He probably has the most experience in this field
beside that of VA6AM. Both make great filters. Just having a filter is not
well said
at field day that famous SDR, very reasonably priced, abundant with
features DID INDEED SPREAD wide band noise ..it was on 10 and wiped out
all thru 80 meters on three other radios of various makes. ( mine was a
k3) ...
maybe all we needed was to have bandpass filters for
You need a filter on the TX radio to prevent its phase noise from being
heard on other bands. Just pressing PTT on the TX radio, even without
putting out any measurable power, will raise the noise floor on multiple
bands. With suitable band decoders driving filter selection,
fast-switching
David,
One need not have a "feeling" about the necessity
of band pass filters. In addition to the concerns
that Paul cited about isolation between ports
in a triplexer or internal antenna port isolation
in a transceiver, there are analytical methods
to determine susceptibility to receiver damage
Hi Paul
Thanks for those thoughts. I see your point re sharing a tri-bander and that
looks like a severe case.
Looking at the number of filters already in place and the low spurii expected
of Elecraft gear, it looks worth considering to down-grade the extra filters.
For instance, the KPA
Hi David
I think any answer is dependent on the station configuration.
For example, if the M/2 station is sharing a single tribander (i.e. one on 20m
and another on 15m) then I imagine filters are still essential as a tri-plexer
will only provide so much isolation.
Another example; If a
Given the improved performance of modern transceivers, is there still a call
for high specification W3NQN band pass filters in a 2-transmitter station? For
example on a Multi-2 contest environment. For instance K3S + KPA + KAT. The
filter fitted between radio and amplifier.
I have the
Good afternoon all. I have a question and would appreciate everyone's
thoughts. I've started trying to get to the field with a buddy of mine. We
take a popup camper and have a day or two operating event. We keep running
into a problem if we both decide to set up stations.
We are generally
Once very simple solution that will provide more than 30 dB attenuation of
the undesired signal is a coax stub. It's just a length of coax connected to
the main transmission line with a T connector that is cut to the proper
length to attenuate the signal from the other station. And, yes, you can
W3NQN wrote a nice series of articles for QST on bandpass filters, a
couple of which were targeted specifically for QRP operations during
Field Day. The design I liked uses a band reject element at the next
harmonic frequency. You can make your own filters from those articles,
and they are
Jack,
20-30 feet separation puts your antennas in each others' near fields,
and they become coupled together [i.e. you're trying to receive on
conductors that are actually parasitically part of your partner's
transmit antenna]. Invest in a roll of coax and get them at least a
couple of
* Whose radio am I protecting, mine or the other guy's?
Your radio
Actually one of the main reasons the filters are used is in DXpedition
or FD setups to restrict the phase noise you transmit to your (phone or
cw) part of the band so there can be other stations operating on the
same
On 4/28/2011 11:39 AM, Rick Stealey wrote:
Actually one of the main reasons the filters are used is in DXpedition
or FD setups to restrict the phase noise you transmit to your (phone or
cw) part of the band so there can be other stations operating on the
same band. So you are protecting the
This is NOT correct. Bandpass filters are just that -- they PASS the
entire ham band, and only STOP signals outside the band.
W2VJN has published the design for a few multi-stub filters that ARE
sharp enough to cut off between phone and CW on relatively wide bands
like 160M, 80M, and 10M.
It is much harder to design a bandpass filter narrow enough to pass the
CW portion of a band while blocking the phone band or vice versa. But
it is not impossible. Several decades ago the Murphy's Marauders
contest club had some giant helical resonators that could do the job.
As I recall the 20
Ok, so I was talking about SHARP bandpass filters.
Most of us are only interested in what we can build or buy at reasonable
cost (not for a Pentagon budget). What you're suggesting MUST be used at
the output of a transmitter to reduce phase noise from the TX, so it
would VERY difficult to
I'm looking to modify a MFJ-1025 (ala W8JI) and need
to build a couple bandpass filters. My first thought
is to steal the filter from the 160M Elecraft board,
heck it works great. I do not have the parts for that
on hand. I do have the parts for the filter in the
KPA.
Other than power handling,
Julius N2WN wrote:
I'm looking to modify a MFJ-1025 (ala W8JI) and need
to build a couple bandpass filters. My first thought
is to steal the filter from the 160M Elecraft board,
heck it works great. I do not have the parts for that
on hand. I do have the parts for the filter in the
KPA.
Other
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