I have looked all over the place for Bandpass filters for both 2m and 70cm antennas to put in front off my LNAs.
Any companies in the US that sells them?????
Thanks,
Herb
Please excuse any typo's as this was sent from my iPhone.
On 6/9/21 11:03 AM, Herb Sims wrote:
I have looked all over the place for Bandpass filters for both 2m and 70cm antennas to put in front off my LNAs.
Any companies in the US that sells them?????
Hello Herb,
Are you trying to avoid de-sense, or do you need a true band-pass for those bands?
If the former; you can use a diplexer[1], such as the Comet CF-4160K, on each of your VHF and UHF paths. See this link:
https://www.amsat.org/a-simple-desense-filter-for-mode-j-satellites/
I, personally, would terminate the unused port in 50 ohms, especially if you intend to transmit through this device. The high-pass/low-pass filters within the diplexer are designed with this impedance in mind. See [2] for details.
If the latter; you can buy a band-pass filter, but they can be somewhat expensive. As a representative sample:
https://www.antennas-amplifiers.com/2-meter-bandpass-filter-transmitting-100...
This is a cheap, low-power version:
https://www.hobbypcb.com/index.php/products/uhf-vhf-radio/144mhz-band-pass-f...
You could also build both diplexers and band-pass filters yourself, usually for far cheaper, depending on your transmit power. A NanoVNA comes in handy to tune these homebrew creations. However, it all comes down to money vs. time. hihi
[1] Note that many amateurs (and some equipment manufacturers!) confuse the terms "duplexer" and "diplexer". See https://en.wikipedia.org/wiki/Duplexer
[2] https://wb4son.com/wpblog/?p=2828
73,
--- Zach N0ZGO
On 6/9/21 11:25 AM, Zach Metzinger wrote:
You could also build both diplexers and band-pass filters yourself, usually for far cheaper, depending on your transmit power. A NanoVNA comes in handy to tune these homebrew creations. However, it all comes down to money vs. time. hihi
Since Herb got me thinking and searching, here's another website about filter designs:
https://wiki.batc.org.uk/Filters
I really like the G3SEK article on inter-digital filters, much like some of the filters that W1GHZ has on his website.
A while back, I related an overload problem I was having on a MAX2640-based 70cm LNA. A water tower with an impressive array of LTE (and other) antennas around its mid-section blasts out energy in the 600-800 MHz range, only a mile from our house.
I solved this with a lumped (discrete) filter on the front-end that had only a few tenths of a dB loss in the band of interest, and then followed the first stage with a 435 MHz SAW filter.
This design has RF relays that engage for RX when powered by DC up the coax, as convention for these devices, but I had to add a PIN diode at the output of the 2nd amplifier to keep the transmitter from destroying the MAR-3 device. A proper sequencer, perhaps using the ALC to keep the transmitter from going to full power for a few milliseconds, might have also solved the problem.
Definitely not the prettiest thing around, but it works:
http://www.n0zgo.net/lna/70cm/max2640/70cm_lna_max2640_annotated.jpg
Keep building!
--- Zach N0ZGO
What I am looking for is a BPF that has very low insertion loss (<0.5dB) and is low cost. I can find BPFs with those specs but they are $300+ each and I need one for both bands….a little pricey…. I thought hams were cheap :)
The SMT parts are high insertion loss so that’s no better from a noise figure standpoint than what I have now (-3dB for coax loss).
The cost is what I’m having problems with. I realize that these BPFs are special…I’m just looking for a better cost bogey.
Thanks,
Herb
On 06/10/21 08:32, Herb Sims wrote:
What I am looking for is a BPF that has very low insertion loss (<0.5dB) and is low cost. I can find BPFs with those specs but they are $300+ each and I need one for both bands….a little pricey…. I thought hams were cheap :)
The SMT parts are high insertion loss so that’s no better from a noise figure standpoint than what I have now (-3dB for coax loss).
The cost is what I’m having problems with. I realize that these BPFs are special…I’m just looking for a better cost bogey.
Hello Herb,
Well .. if you're looking for the cheap solution, you'll be buying something made by near-slave labor in China that may or may not actually solve the problem.
Not to go too far down the political rabbit hole: people complain that there aren't enough non-China products, but yet they aren't willing to spend another $50 to back up that statement. Domestic jobs continue to disappear and people's houses become cluttered with flimsy junk.
An axiom of engineering: Cheap, fast, good. Pick any two.
--- Zach N0ZGO
Hi Herb. Unfortunately bandpass filters rated at full output power with that spec are usually big and hence expensive. Although a compromise, a decent design of high pass filter and low pass filter would be cheap less than 1/10th the price and have a loss of 0.2dB.Maybe the 2m followed by a low pass and a High pass in front of the 70cm. ? 73 David
-----Original Message----- From: Herb Sims herb.sims@mchsi.com CC: amsat-bb@amsat.org Sent: Thu, 10 Jun 2021 14:32 Subject: [AMSAT-BB] Re: BPF for 2m and 70cm?
What I am looking for is a BPF that has very low insertion loss (<0.5dB) and is low cost. I can find BPFs with those specs but they are $300+ each and I need one for both bands….a little pricey…. I thought hams were cheap :) The SMT parts are high insertion loss so that’s no better from a noise figure standpoint than what I have now (-3dB for coax loss). The cost is what I’m having problems with. I realize that these BPFs are special…I’m just looking for a better cost bogey. Thanks, Herb
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Mini-circuits has sub $100 filters available suitable for receiving applications:
https://www.minicircuits.com/WebStore/RF-Filters.html
Meeting the 0.5 dB insertion loss specification might be difficult though.
-Joe KM1P
I think there are TWO incompatible applications being discussed:
1) The original request was for narrowband BPF for portable operating on a mountain top in the presence of commercial transmitters. Usually needs a relatively large cavity or heloical resonator. This is for the annual APpalachian Trail GOlden Packet event 17 July http://aprs.org/at-golden-packet.html
2) The more common AMSAT need for a LPF to prevent front end overload of the third harmonic of a VHF upllink into the UHF receiver.
The solutions are very different. - Bob, WB4APR
On Thu, Jun 10, 2021 at 2:08 PM Joseph B. Fitzgerald < jfitzgerald@alum.wpi.edu> wrote:
Mini-circuits has sub $100 filters available suitable for receiving applications:
https://www.minicircuits.com/WebStore/RF-Filters.html
Meeting the 0.5 dB insertion loss specification might be difficult though.
-Joe KM1P
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Herb, I built two such filters based on construction directions found on page 500 of the 1973 ARRL Handbook under Strip Line Filters. I have seen the filters in several issues of the Handbook and they are simple enough that I expect it will be shown in other years of the Handbook. I used them in my full duplex satellite operations. The third harmonic of my two meter uplink transmitter fell near my downlink 70cm frequency and was causing desensitization in reception. The parts were an aluminum mini-box, two coax recepticals mounted on the box, an air variable capacitor (disc for UHF). The strip line is a strip of aluminum mounted end to end in the box. Let me know if you can’t find the article and I’ll copy and email it to you. The filters got rid of the descendent problem.
73, Roy Welch, W0SL
Sent from my iPad R/D/Gd/Ggd
On Jun 9, 2021, at 11:03 AM, Herb Sims herb.sims@mchsi.com wrote: I have looked all over the place for Bandpass filters for both 2m and 70cm antennas to put in front off my LNAs.
Any companies in the US that sells them?????
Thanks,
Herb
Please excuse any typo's as this was sent from my iPhone.
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
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http://www.dci.ca/?Section=Products&SubSection=Amateur
We use them on our repeaters. They work well
Stephen Nipper N7DJX
On Wed, Jun 9, 2021 at 10:04 AM Herb Sims herb.sims@mchsi.com wrote:
I have looked all over the place for Bandpass filters for both 2m and 70cm antennas to put in front off my LNAs.
Any companies in the US that sells them?????
Thanks,
Herb
Please excuse any typo's as this was sent from my iPhone.
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
Mini-Circuits makes some SMT filters. The downside is that they're SMT with small solder pads. The other thing is, they are power limited to 0.5W.
https://www.minicircuits.com/WebStore/dashboard.html?model=RBP-140%2B https://www.minicircuits.com/WebStore/dashboard.html?model=RBP-440%2B
You can buy them individually from Mouser or Digikey, and I'm pretty sure you can order *free* samples of them from Mini-Circuits.
You can buy breakout PCBs for them from ebay, for example (the boards use SMA connectors): https://www.ebay.com/itm/401190029762?hash=item5d68ca09c2:g:SmQAAOSw4shX3IVv
The downside is that they're SMT with small solder pads. The other thing is, they are power limited to 0.5W. They offer other types of bandpass filter, but I haven't done an exhaustive search... I've used them for the receive end, they work as advertised.
Brad AC0ZJ
On 6/9/2021 10:03 AM, Herb Sims wrote:
I have looked all over the place for Bandpass filters for both 2m and 70cm antennas to put in front off my LNAs.
Any companies in the US that sells them?????
Thanks,
Herb
Please excuse any typo's as this was sent from my iPhone.
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
Herb
I know you said BPF. A lot of us use the BLP-200+ LPF from Mini Circuits on the 2m side to help with desense
https://www.minicircuits.com/WebStore/dashboard.html?model=BLP-200%2B
On Wed, Jun 9, 2021 at 5:18 PM Brad Van Slyke via AMSAT-BB < amsat-bb@amsat.org> wrote:
Mini-Circuits makes some SMT filters. The downside is that they're SMT with small solder pads. The other thing is, they are power limited to 0.5W.
https://www.minicircuits.com/WebStore/dashboard.html?model=RBP-140%2B https://www.minicircuits.com/WebStore/dashboard.html?model=RBP-440%2B
You can buy them individually from Mouser or Digikey, and I'm pretty sure you can order *free* samples of them from Mini-Circuits.
You can buy breakout PCBs for them from ebay, for example (the boards use SMA connectors):
https://www.ebay.com/itm/401190029762?hash=item5d68ca09c2:g:SmQAAOSw4shX3IVv
The downside is that they're SMT with small solder pads. The other thing is, they are power limited to 0.5W. They offer other types of bandpass filter, but I haven't done an exhaustive search... I've used them for the receive end, they work as advertised.
Brad AC0ZJ
On 6/9/2021 10:03 AM, Herb Sims wrote:
I have looked all over the place for Bandpass filters for both 2m and
70cm antennas to put in front off my LNAs.
Any companies in the US that sells them?????
Thanks,
Herb
Please excuse any typo's as this was sent from my iPhone.
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions expressed
are solely those of the author, and do not reflect the official views of
AMSAT-NA.
Acceptable Use and Privacy Policies available at
https://www.amsat.org/about-amsat/
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
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And you can put WAY more than 0.5w through these. I have, as many others have.
On Wed, Jun 9, 2021 at 6:42 PM Brian Wilkins ko4aqf@gmail.com wrote:
Herb
I know you said BPF. A lot of us use the BLP-200+ LPF from Mini Circuits on the 2m side to help with desense
https://www.minicircuits.com/WebStore/dashboard.html?model=BLP-200%2B
On Wed, Jun 9, 2021 at 5:18 PM Brad Van Slyke via AMSAT-BB < amsat-bb@amsat.org> wrote:
Mini-Circuits makes some SMT filters. The downside is that they're SMT with small solder pads. The other thing is, they are power limited to 0.5W.
https://www.minicircuits.com/WebStore/dashboard.html?model=RBP-140%2B https://www.minicircuits.com/WebStore/dashboard.html?model=RBP-440%2B
You can buy them individually from Mouser or Digikey, and I'm pretty sure you can order *free* samples of them from Mini-Circuits.
You can buy breakout PCBs for them from ebay, for example (the boards use SMA connectors):
https://www.ebay.com/itm/401190029762?hash=item5d68ca09c2:g:SmQAAOSw4shX3IVv
The downside is that they're SMT with small solder pads. The other thing is, they are power limited to 0.5W. They offer other types of bandpass filter, but I haven't done an exhaustive search... I've used them for the receive end, they work as advertised.
Brad AC0ZJ
On 6/9/2021 10:03 AM, Herb Sims wrote:
I have looked all over the place for Bandpass filters for both 2m and
70cm antennas to put in front off my LNAs.
Any companies in the US that sells them?????
Thanks,
Herb
Please excuse any typo's as this was sent from my iPhone.
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership.
Opinions expressed
are solely those of the author, and do not reflect the official views
of AMSAT-NA.
Acceptable Use and Privacy Policies available at
https://www.amsat.org/about-amsat/
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
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This was confirmed by Mike W8LID a year or so ago via a long twitter conversation and confirmation by MC team. I personally would not run 100W through the filter but some reasonable low power level will work fine.Confirmed on past AMSAT-BB discussions in the past. Adrian AA5UK
On Thursday, June 10, 2021, 9:43:51 AM CDT, Don KB2YSI kb2ysi@gmail.com wrote:
And you can put WAY more than 0.5w through these. I have, as many others have. On Wed, Jun 9, 2021 at 6:42 PM Brian Wilkins ko4aqf@gmail.com wrote:
Herb I know you said BPF. A lot of us use the BLP-200+ LPF from Mini Circuits on the 2m side to help with desense https://www.minicircuits.com/WebStore/dashboard.html?model=BLP-200%2B
On Wed, Jun 9, 2021 at 5:18 PM Brad Van Slyke via AMSAT-BB amsat-bb@amsat.org wrote:
Mini-Circuits makes some SMT filters. The downside is that they're SMT with small solder pads. The other thing is, they are power limited to 0.5W.
https://www.minicircuits.com/WebStore/dashboard.html?model=RBP-140%2B https://www.minicircuits.com/WebStore/dashboard.html?model=RBP-440%2B
You can buy them individually from Mouser or Digikey, and I'm pretty sure you can order *free* samples of them from Mini-Circuits.
You can buy breakout PCBs for them from ebay, for example (the boards use SMA connectors): https://www.ebay.com/itm/401190029762?hash=item5d68ca09c2:g:SmQAAOSw4shX3IVv
The downside is that they're SMT with small solder pads. The other thing is, they are power limited to 0.5W. They offer other types of bandpass filter, but I haven't done an exhaustive search... I've used them for the receive end, they work as advertised.
Brad AC0ZJ
On 6/9/2021 10:03 AM, Herb Sims wrote:
I have looked all over the place for Bandpass filters for both 2m and 70cm antennas to put in front off my LNAs.
Any companies in the US that sells them?????
Thanks,
Herb
Please excuse any typo's as this was sent from my iPhone.
Sent via AMSAT-BB(a)amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Acceptable Use and Privacy Policies available at https://www.amsat.org/about-amsat/
View archives of this mailing list at https://mailman.amsat.org/hyperkitty/list/amsat-bb@amsat.org To unsubscribe send an email to amsat-bb-leave(a)amsat.org Manage all of your AMSAT-NA mailing list preferences at https://mailman.amsat.org
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participants (11)
-
Adrian Engele -
Brad Van Slyke -
Brian Wilkins -
David G0MRF -
Don KB2YSI -
H. Stephen Nipper -
Herb Sims -
Joseph B. Fitzgerald -
Robert Bruninga -
Roy -
Zach Metzinger