He says that this simple input band-pass filter BPF might be of interest to anyone suffering from strong AM broadcast stations that are causing overloads…. David suffers from three nearby AM radio broadcast stations that overload the front ends of several of his receivers, including the SDRplay RSP and this is an ideal, low cost solution.
He built this circuit from junk parts and commented that Amidon T iron powder cores would have made a better design, but that he decided to keep costs down with this design. I like it!!! Thanks for this, Thomas. Much as I enjoy winding toroids, I rather like that this uses molded inductors, and will fit into a fairly small space.
Great to hear from you. Pingback: 1. Please compare the attenuation curve of the HP to this. I also perceive this as a tiny little bit spammy, Mr. You offer cables with most products but again, all BNC only. Hello Mr. Just plug and play. Of course, if you like DIY, go ahead and do it. The BNC discussion is endless. Some wants N and some SMA. We also like SMA, no question. It would saves us a lot of money. We really made up our minds if we should do the next one with SMA. Keep listening Dennis.
I agree. The form factor for interfacing with humans has been reduced about as much as possible. I use BNC for nearly every connection as connectivity is quick and reliable enough. Thank you German public radio for saving me from having to build one of those! That RF got into everything. This would not be a problem in tube radios because they can take the overload with their wide dynamic range.
I ran into this problem when I got my first transistor shortwave, and had a very similar solution.All thumb nails expand to additional photos with full descriptions.
TV Interference - Steps towards curing TVi interference have been described in other chapters, such as rearranging equipment layout and equipment bonding, Although this cured specific problems, they are none the less good operating practice, when setting up an amateur station on a permanent basis.
The requirement to cure transmitter interference to local television reception requires the most stringent attention to remove ground loops, improve station bonding, improve grounding, and prevent RF leakage.
As stated, TVi is very difficult to remove, and understand why we have it in the first place. It is essential to eliminate all known factor's, one by one. Test measurements noted before carrying out the station refurbishment showed that interference occurred with only a few watts of transmitter power. After refurbishment, no detectable interference was present with watts, on any TV channel.
Filters At this point you may wish to go no further, but if you require to increase your transmission output power from watts to 1Kw or more, you may not be surprised to hear that we have, at these higher power levels, interference appearing once again.
All steps taken to cure TV interference so far, has been a matter of good engineering practice, without resorting to technical solutions. However we now have to enter these realms, in order to understand why we have TVi. Traditionally it has always been good practice to fit at least one good quality low pass filter LPF. The purpose of fitting a filter at the transmitter output, is to reduce or hinder the passage of any RF above 30 Mhz.
Unless the manufacture provided a graph, or details of its response, you will be in the dark as to what it really does. At best, fitting one is very misleading and unless it is tailored for your requirements will not effect a cure.
I have provided a table of amateur bands and harmonically generated frequency's, that fall within Band One TV channels. See Excel table. In the early days, sensitivity of TV sets were very poor, several hundred micro volts needed for a good quality pictures. At my home location, I have measured the TV reception signal to be around micro volts, on the end of a pair of rabbits ears, the type of antenna normally attached to the rear of the TV set in this area. We now have our fist set of known measurements that can be used in the design of our specific filters.
To understand the effectiveness of our filter, usually expressed in Decibels relative to one watt, it is necessary to subtract the filters insertion loss at the specified frequency, and convert the result into micro volts.2000 jeep wrangler 4 cylinder fuel fuse keeps
We can then visualize a better picture of the progress that we are making and the necessary insertion losses required relative to our TV interference. Decibel measurements are relative in expressing a given power or voltage ratio. I have chosen to work in pure micro volts relative to 50 ohms, as this is a tangible figure which can be measured, or visualized in our case at the TV antenna plug. If you own a receiver that covers VHF the S meter is already calibrated in micro volts, and will serve as a very useful tool.
I have constructed a working table that carries out all conversions, and is easy to see that with a given transmitter power, how many micro volts are radiated from our antenna after fitting our filter. An example of a standard situation is that with a power output of watts the published figures shown in my TS service manual, is that all harmonics are Db down on carrier.
This then leave 1 watt radiated into the surrounding air at 56Mhz before filtering. If we convert 1 watt into 50 ohms into micro volts the lever entering our television set is See DB Conversion Table.
Remembering that our measured TV reception signal level is micro volt, it is no wonder that we have TV interference. If the exercise is repeated for watts, then the interference to our TV receiver is a staggering 7 milli Volts. Using the Excel spread sheet to calculate the filter loss required, is easy. By inserting loss required to take the harmonic down to say 50 micro volt with watts, shows we require a filer insertion loss of db. Taking a best guess that our old LPF inserts typically only db we can now see why our filter have very little, or no effect in reducing TV interference.
We could insert several filters in series, but without knowing the exact specification, is of little use. Which had no effect in curing my interference. When I had both analyzed with a spectrum analyzer, the maximum attenuation occurred well outside any harmonic's generated by my transmitter.
The filters arrived without any specification sheet. The internal construction being open layout, implied that the filters were unlikely to achieve any significant attenuation anyway. The insertion loss on ten meters was in the order of several dB's not a good show for MFJ.Probably the best DX site in the world.
DX news.British emergency
Construction project High-pass filter Enjoying Radio, November edited by David Newkirk A "high-pass" filter is one designed to pass all signals above a certain frequency -- the cutoff frequency.
The purpose of this is clear: if you want to receive everything above, say, 2 MHz, and you're troubled by severe overloading because of MW broadcast signals 0.
RF and AF Filters
Note that the action about the cutoff frequency is not "as sharp as a knife"; a high-pass filter with a 2-MHz cutoff frequency doesn't pass kHz signals beautifully and chop off kHz signals to the point where they're not there.
Such filters can be rated by how many decibels of rolloff plunge in signal level they afford per octave per halving [for high-pass filters] or per doubling [for lowpass filters] of frequency. Filter are easy to build and can solve one problems almost magically when properly applied. Here's Chuck Bolland with the filter he built to chop MW interference to his SW efforts: Anyone having trouble with nearby nediumwave stations swamping his or her shortwave receiver?
Here is the description of a high pass filter that will help overcome that problem. This filter will attenuate all signals below kHz by at least 20dB. This could be done with an antenna tuner, too, but, unlike an antenna tuner, this filter does not affect the shortwave spectrum. In fact, it improves that portion of the spectral by eliminating the mediumwave noise. Web Archive Mail Archive. Search all HCDX mail since About us.This forum is now suspended and will not accept any new posts or account registrations.
For technical support relating to SDRplay hardware or software, please open up a support ticket via www.Rxz biru grey
Privacy Terms. SDRplay Community Forum This forum is now suspended and will not accept any new posts or account registrations. Quick links. Forum rules. Continued in next post for text amendment purposes. A sharp High Pass filter placed between antenna and RSP class receiver input, can protect the front end circuitry by effectively reducing or eliminating the unwanted Medium Wave band signals, extremely strong at night time.
High Pass filters are designed from tabulated Low Pass prototypes through a transformation process set up on a single Excel spreadsheet. Since the HF band above 2 MHz covers several octaves, a Cauer type prototype is not suitable because these filter types, having attenuation poles near the passband, can produce parasitic and unwanted signal transmission at higher frequencies, caused by imperfections in the filter components.
On the contrary, a Low Pass Cauer type filter, as used for LF reception in the previous thread, is suitable because of the small size of the required passband below the bandstop, where component imperfections are not significant. For instance a Chebyshev prototype: TH 0. The chosen Chebyshev prototype is a TH 0. You do not have the required permissions to view the files attached to this post.
The resulting highpass prototype has 5 capacitors and 4 coils.
A simple homebrew high pass filter
If we used the shunt first prototype, we would end up with 4 capacitors and 5 coils. Since in general coil Q is significantly lower than capacitor Q e. In the real world capacitors have a parallel loss resistance and inductors have a series loss resistance and the quality factor Q of these components is the ratio between component reactance and component loss resistance.
It is essential to predict insertion loss at the cutoff frequency. The Excel spreadsheet in Figure 5, calculates the component values from the original prototype and the filter insertion loss for the Q values mentioned above.Amiko alien mini
From Figure 5 the predicted insertion loss at 2 MHz is 0. Since capacitors introduce lower losses than inductors, a filter with fewer inductors will have lower insertion loss, all other conditions being equal.
In the next post we shall examine inductor design and will optimize inductor Q factor by manipulating coil parameters. The "COIL 32" software, readily available, can be used to optimise inductor parameter selection. In general larger diameter coils, wound with larger diameter wire and with a pitch that keeps turns spaced, exhibit a higher Q than smaller diameter close wound coils with thinner wire.Forgot Password? An RF filter is an electrical circuit configuration network designed to have specific characteristics with respect to the transmission or attenuation of various frequencies that may be applied to it.
This filter can give you that extra boost. Its primary application is reducing interference between HF stations operating in close proximity.
May QST pp. Free student versions are available for download. Secure Site Login Forgot Password? RF and AF Filters Introduction An RF filter is an electrical circuit configuration network designed to have specific characteristics with respect to the transmission or attenuation of various frequencies that may be applied to it.
There are three general types of RF filters: A high-pass filter similarly has a cut-off frequency, above which there is little or no loss in transmission, but below which there is considerable attenuation. Its behavior is the opposite of that of the low-pass filter.
A low-pass filter is one that will permit all frequencies below a specified one called the cut-off frequency to be transmitted with little or no loss, but that will attenuate all frequencies above the cut-off frequency.
High-pass and low-pass filters can be difficult to construct properly. Whenever possible, many amateurs simply buy them. A band-pass filter is one that will transmit a selected band of frequencies with substantially no loss, but that will attenuate all frequencies either higher or lower than the desired band.
Soon you will not be able to create a secure connection to our web site using TLS 1. Please upgrade your browser from current version. Learn more about TLS. High-Pass Filter, 1. We ship in-stock parts via ground shipping the same day if ordered by pm Eastern. Monday through Friday. Learn More. We're confident our prices are the lowest.
You can return any new or unused item within 10 days of the date your item was shipped and we will refund the full purchase price. These filters are fitted with ohm F connectors and will provide out-of-band attenuation of 30 dB at 1, kHz, and up to 70 dB at 1, kHz and below.
Insertion loss is an average 2 dB in the pass band. Their roll-off slope begins at 1, kHz, the bottom edge of meters, and reaches 60 dB attenuation at 1, kHz! These filters were designed to be used with shortened vertical arrays and other receive antenna systems that experience interference from local AM broadcasters.
They are receive-only, high-pass filters designed for insertion in 75 ohm coaxial cable-fed Amateur Radio and SWL systems. High pass starts at 1. Are you building up a new active array?The proliferation of LTE signal towers and connected LTE devices are a common cause of intermittent television signal disruption because mobile carriers operate on frequencies that can be very close to your broadcast TV frequencies.
These disruptions can result in weak signals, pixelation or even channel loss, and can be especially disruptive when using an amplifier with your TV antenna. Channel Master highly recommends using an LTE Filter with TV antenna installations in metro and suburban areas in order to assure optimum performance. If you require an amplifier for your TV antenna installation, we recommend the Channel Master Amplifya high-end amplifier that includes an internal LTE filter.
Become a Channel Master VIP Newsletter Member for full access to online tools and resources plus receive our monthly newsletter containing exclusive industry news, product announcements, videos, special offers and more. We value our members and their privacy. Downloads CM Instruction Sheet. Email Submit. Channel Master. Contact Us. All Rights Reserved.
LTE Filter. Technical Specifications. CM Instruction Sheet. FLAT enna LTE Filter Experience. Good LTE Filter. Happy Customer. Reviewer: Jimmy from Haughton La.
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