I know this is a long shot, but does anyone have a pair of channel elements crystalled for 147.180 TX, 147.780 RX for the MSR-2000 they'd like to sell? I thought I'd check here before I order a set from Klove. Thanks in advance.
?
Terry KM5UQ
|
Re: Astron RM-50M conversion
A Victron Smart with a Victron SmartShunt right at the battery (such that the shunt only sees battery current and not load current) is a reasonable approach if you have lead-acid (flooded or AGM). See this note in the manual for why: In order to end the absorption phase at the correct point, it is important that the true current flow into the battery is referenced in relation to the tail current threshold, rather than the charger output current which may be significantly higher; if any loads are powered while charging a portion of the charger output current will be flowing directly to the loads, making the tail current condition more difficult or impossible to meet without current sense.
Since I'm not stuck on the Iota, a Victron Smart IP22, IP43, IP67 12/30 or 12/50 - are spec'd to 14.7v max.
Quick review of battery products...
LiTime - max V = 14.6
BattleBorn = 14.7
WattCycle = 14.8
Bioenno = 14.6
There doesn't seem to be a cleaner/smarter way to do this other than ye olde Charger -> Batteries -> Load(s) if the goal is to have no power interruption when AC mains drops/burps.??
Then consider what's alive, presenting a load, in the rack, for how long.? A certain popular/familiar radio draws ~10A at 50W output.? Another popular piece of gear for linking... CDM-1250, ~8A @ 20-25w.? Controller bits, AllStar node, networking... another 5A perhaps.? 25A... for what run cycle?? Our longest on-air time is an intermittent 15-20 minutes of weekly net check-in, then continuous playout of AR Newsline.??
Ought to be able to cover that with 2x 100AH batteries and charger, and recover reasonably soon.? That's essentially what I've got at home, plus 400w of solar, running for the past 6-8 months.? The whole shack - HF, VHF/UHF rigs, and local repeater seem to be doing pretty well and is 'idling' at 14.38 v - can't find my ammeter to re-check the idle vs active draws.
|
A DB 201 or 212 is the best on lowband...there are a lot left abandoned at sites in still good shape. You can probably find one looking around...cheaper than a new one but it WILL work
Chris WB5ITT?
I've been tasked by our Red Cross regional director to get a 47 MHz antenna installed for "low band" VHF use on one of their buildings.? It seems to be a difficult band to find commercial antennas for, but the Red Cross is still quite active on the band.
?
I'm looking at the Andrew DB201-L.? But everything I find about it is years old and I'm having trouble finding a source to purchase one.
?
Is it still manufactured?? And if so, where can I purchase one?? If not, is there a newer/better alternative before we just build a ground plane antenna (I'd rather not have to, to be honest).
?
I know this isn't strictly repeater related, but I've found other topics on this specific antenna in this forum (although quite old).
?
Thanks!
73,
Marlo
KA2IRQ
?
|
Kreco , stupid auto correct.?
Ken Pearce? N4KCD? Commerce Township, MI
toggle quoted message
Show quoted text
On Apr 26, 2025, at 18:43, Ken Pearce via groups.io <n4kcd@...> wrote:
? Oreo is good and I use either Tessco or Talley.?
Ken Pearce? N4KCD? Commerce Township, MI On Apr 26, 2025, at 18:32, Chuck Kelsey via groups.io <wb2edv@...> wrote:
?
I believe Sinclair and Comprod still
make their versions.
Chuck
WB2EDV
On 4/26/2025 6:19 PM, Marlo Montanaro -
KA2IRQ via groups.io wrote:
I've been tasked by our Red Cross regional director to get a
47 MHz antenna installed for "low band" VHF use on one of their
buildings.? It seems to be a difficult band to find commercial
antennas for, but the Red Cross is still quite active on the
band.
?
I'm looking at the Andrew DB201-L.? But everything I find
about it is years old and I'm having trouble finding a source to
purchase one.
?
Is it still manufactured?? And if so, where can I purchase
one?? If not, is there a newer/better alternative before we just
build a ground plane antenna (I'd rather not have to, to be
honest).
?
I know this isn't strictly repeater related, but I've found
other topics on this specific antenna in this forum (although
quite old).
?
Thanks!
73,
Marlo
KA2IRQ
?
|
Oreo is good and I use either Tessco or Talley.?
Ken Pearce? N4KCD? Commerce Township, MI
toggle quoted message
Show quoted text
On Apr 26, 2025, at 18:32, Chuck Kelsey via groups.io <wb2edv@...> wrote:
?
I believe Sinclair and Comprod still
make their versions.
Chuck
WB2EDV
On 4/26/2025 6:19 PM, Marlo Montanaro -
KA2IRQ via groups.io wrote:
I've been tasked by our Red Cross regional director to get a
47 MHz antenna installed for "low band" VHF use on one of their
buildings.? It seems to be a difficult band to find commercial
antennas for, but the Red Cross is still quite active on the
band.
?
I'm looking at the Andrew DB201-L.? But everything I find
about it is years old and I'm having trouble finding a source to
purchase one.
?
Is it still manufactured?? And if so, where can I purchase
one?? If not, is there a newer/better alternative before we just
build a ground plane antenna (I'd rather not have to, to be
honest).
?
I know this isn't strictly repeater related, but I've found
other topics on this specific antenna in this forum (although
quite old).
?
Thanks!
73,
Marlo
KA2IRQ
?
|
I believe Sinclair and Comprod still
make their versions.
Chuck
WB2EDV
On 4/26/2025 6:19 PM, Marlo Montanaro -
KA2IRQ via groups.io wrote:
toggle quoted message
Show quoted text
I've been tasked by our Red Cross regional director to get a
47 MHz antenna installed for "low band" VHF use on one of their
buildings.? It seems to be a difficult band to find commercial
antennas for, but the Red Cross is still quite active on the
band.
?
I'm looking at the Andrew DB201-L.? But everything I find
about it is years old and I'm having trouble finding a source to
purchase one.
?
Is it still manufactured?? And if so, where can I purchase
one?? If not, is there a newer/better alternative before we just
build a ground plane antenna (I'd rather not have to, to be
honest).
?
I know this isn't strictly repeater related, but I've found
other topics on this specific antenna in this forum (although
quite old).
?
Thanks!
73,
Marlo
KA2IRQ
?
|
Kreco makes both folded monopole ground plane and coaxial dipoles for VHF lo band. For something a little less expensive Child’s Antenna Company makes a VHF lo coaxial dipole.?
|
Re: Astron RM-50M conversion
Since I'm not stuck on the Iota, a Victron Smart IP22, IP43, IP67 12/30 or 12/50 - are spec'd to 14.7v max.
Quick review of battery products...
LiTime - max V = 14.6
BattleBorn = 14.7
WattCycle = 14.8
Bioenno = 14.6
There doesn't seem to be a cleaner/smarter way to do this other than ye olde Charger -> Batteries -> Load(s) if the goal is to have no power interruption when AC mains drops/burps.??
Then consider what's alive, presenting a load, in the rack, for how long.? A certain popular/familiar radio draws ~10A at 50W output.? Another popular piece of gear for linking... CDM-1250, ~8A @ 20-25w.? Controller bits, AllStar node, networking... another 5A perhaps.? 25A... for what run cycle?? Our longest on-air time is an intermittent 15-20 minutes of weekly net check-in, then continuous playout of AR Newsline.??
Ought to be able to cover that with 2x 100AH batteries and charger, and recover reasonably soon.? That's essentially what I've got at home, plus 400w of solar, running for the past 6-8 months.? The whole shack - HF, VHF/UHF rigs, and local repeater seem to be doing pretty well and is 'idling' at 14.38 v - can't find my ammeter to re-check the idle vs active draws.
|
I've been tasked by our Red Cross regional director to get a 47 MHz antenna installed for "low band" VHF use on one of their buildings.? It seems to be a difficult band to find commercial antennas for, but the Red Cross is still quite active on the band.
?
I'm looking at the Andrew DB201-L.? But everything I find about it is years old and I'm having trouble finding a source to purchase one.
?
Is it still manufactured?? And if so, where can I purchase one?? If not, is there a newer/better alternative before we just build a ground plane antenna (I'd rather not have to, to be honest).
?
I know this isn't strictly repeater related, but I've found other topics on this specific antenna in this forum (although quite old).
?
Thanks!
73,
Marlo
KA2IRQ
?
|
Re: Motorola SLR5700 DMR Repeater
Hey Bob, don’t worry I’ve had my turn in the bucket. This list has some extremely knowledgeable guys on here and I know you, your background and your technical background, they don’t. I appreciate their input and knowledge trust, but you’re right we are suppose
to Mentor one another and give grace when someone makes a mistake. Can’t tell you how many times I’ve responded to a post not knowing I’m a few comments behind. Take care my friend, we should grab lunch at Annie’s sometime.
toggle quoted message
Show quoted text
On Apr 26, 2025, at 13:02, bob ehrhorn via groups.io <behrhorn@...> wrote:
?
This Message is From an External Sender
This message came from outside your organization.
Hi Guys
I am Sorry my reply to the original question should have been: Check your repeater settings, so it does not beacon,
WOW I got it !! Sorry I missed the post from another SL5700 user explaining what may be going on and how to correct it.
Bob
P.S. Chris where would you like me to go to turn in my License? I've seen a fer people pop off hot messages in frustration and my apologies to the group for trying to explain. I thought we used to Mentor people in the art or repeater building and troubleshooting.
On Friday, April 25, 2025 at 01:56:59 PM PDT, Chris Boone WB5ITT via groups.io <setxtelecom@...> wrote:
Beaconing 24/7 is permitted outside the automatic beacon subbands ONLY IF a control operator of the repeater xmtr, NOT the network, is monitoring the actual RF channel to prevent interference.. geese why do people NOT READ THE RULES? sorry folks
but part 97 is part 97. ..if you can't follow them, turn in your license and go back to 27MHz or GMRS.?
If you think this is wrong, ask Riley or Laura...they've both sent notices to repeaters beaconing IDs , etc.
Chris WB5ITT
Hi guys
The SLR5700 has a beacon that it transmits in DMR mode so the mobile and hand held units can synchronize the TDMA time slots and know there within range of the repeater???
WARNING: Do not click links or attachments unless you recognize
the sender and know the email is safe.
|
Re: THREAT TO 222-225MHz Spectrum Getting Worse with additional licenses issued outside of California
On Sat, Apr 26, 2025 at 04:56 PM, Chuck Kelsey wrote:
NOTHING is safe if "big money" wants it... NOTHING.
Chuck
On 4/26/2025 4:25 PM, John N. Hudson III via groups.io wrote:
Bob we have discussed this and you have a valid point. But as you know the spectrum is crowded in SoCal with only a few High Level channels, Trustees are limited to 3 pairs but they can co-channel themselves as long as it doesn't cause issues. We've been asked about making the one channel high level, at this point we're hoping more than one person will consider investing in a digital 220 repeater. We may have to reconsider if no one steps up, I personally would like to see one operational with propagation of 220 having characteristics of VHF and UHF the coverage may surprise folks.
?
Side Note: Today during the 220SMA meeting something I didn't know was CAOS Capital has tested on the 2 meter spectrum in addition to 222-225 MHz, additionally, they have ether tried to receive licenses or had licenses from 27MHz-500MHz. Remember, Amateur Radio is secondary in the 420-450MHz with Military as Primary. Meaning, they could conduct tests in the UHF HAM Spectrum so NO spectrum is safe and why its important whether you use 220 or not, ALL HAMS need to fight for our spectrum because none are safe. I will be posting more information as it becomes available. Rick W6RE has done a deep dive on the company and head engineer on this project with some very interesting findings. It was an eye opener for me this morning, stay tuned. Lastly, if you want to make a proposal to 220 SMA to install a Digital Repeater even at a high level site nothings says you can't and it will cause us to come back around and revisit the subject. All the Best,
?
John N. Hudson III, WA6HYQ
?
Bingo. The same reason Anterix is spending $250m to gain the rest of the 896-901/935-940 for broadband/private LTE. Follow the money. Mike
|
Re: THREAT TO 222-225MHz Spectrum Getting Worse with additional licenses issued outside of California
NOTHING is safe if "big money" wants
it... NOTHING.
Chuck
On 4/26/2025 4:25 PM, John N. Hudson
III via groups.io wrote:
toggle quoted message
Show quoted text
Bob we have discussed this and you have a valid point. But as
you know the spectrum is crowded in SoCal with only a few High
Level channels, Trustees are limited to 3 pairs but they can
co-channel themselves as long as it doesn't cause issues. We've
been asked about making the one channel high level, at this
point we're hoping more than one person will consider investing
in a digital 220 repeater. We may have to reconsider if no one
steps up, I personally would like to see one operational with
propagation of 220 having characteristics of VHF and UHF the
coverage may surprise folks.
?
Side Note: Today during the 220SMA meeting something I didn't
know was CAOS Capital has tested on the 2 meter spectrum in
addition to 222-225 MHz, additionally, they have ether tried to
receive licenses or had licenses from 27MHz-500MHz. Remember,
Amateur Radio is secondary in the 420-450MHz with Military as
Primary. Meaning, they could conduct tests in the UHF HAM
Spectrum so NO spectrum is safe and why its important whether
you use 220 or not, ALL HAMS need to fight for our spectrum
because none are safe. I will be posting more information as it
becomes available. Rick W6RE has done a deep dive on the company
and head engineer on this project with some very interesting
findings. It was an eye opener for me this morning, stay tuned.
Lastly, if you want to make a proposal to 220 SMA to install a
Digital Repeater even at a high level site nothings says you
can't and it will cause us to come back around and revisit the
subject. All the Best,
?
John N. Hudson III, WA6HYQ
?
|
Re: THREAT TO 222-225MHz Spectrum Getting Worse with additional licenses issued outside of California
Bob we have discussed this and you have a valid point. But as you know the spectrum is crowded in SoCal with only a few High Level channels, Trustees are limited to 3 pairs but they can co-channel themselves as long as it doesn't cause issues. We've been asked about making the one channel high level, at this point we're hoping more than one person will consider investing in a digital 220 repeater. We may have to reconsider if no one steps up, I personally would like to see one operational with propagation of 220 having characteristics of VHF and UHF the coverage may surprise folks.
?
Side Note: Today during the 220SMA meeting something I didn't know was CAOS Capital has tested on the 2 meter spectrum in addition to 222-225 MHz, additionally, they have ether tried to receive licenses or had licenses from 27MHz-500MHz. Remember, Amateur Radio is secondary in the 420-450MHz with Military as Primary. Meaning, they could conduct tests in the UHF HAM Spectrum so NO spectrum is safe and why its important whether you use 220 or not, ALL HAMS need to fight for our spectrum because none are safe. I will be posting more information as it becomes available. Rick W6RE has done a deep dive on the company and head engineer on this project with some very interesting findings. It was an eye opener for me this morning, stay tuned. Lastly, if you want to make a proposal to 220 SMA to install a Digital Repeater even at a high level site nothings says you can't and it will cause us to come back around and revisit the subject. All the Best,
?
John N. Hudson III, WA6HYQ
?
|
Re: Motorola SLR5700 DMR Repeater
Hi Guys
I am Sorry my reply to the original question should have been: Check your repeater settings, so it does not beacon,
WOW I got it !! Sorry I missed the post from another SL5700 user explaining what may be going on and how to correct it.
Bob
P.S. Chris where would you like me to go to turn in my License? I've seen a fer people pop off hot messages in frustration and my apologies to the group for trying to explain. I thought we used to Mentor people in the art or repeater building and troubleshooting.
On Friday, April 25, 2025 at 01:56:59 PM PDT, Chris Boone WB5ITT via groups.io <setxtelecom@...> wrote:
Beaconing 24/7 is permitted outside the automatic beacon subbands ONLY IF a control operator of the repeater xmtr, NOT the network, is monitoring the actual RF channel to prevent interference.. geese why do people NOT READ THE RULES? sorry folks but part 97 is part 97. ..if you can't follow them, turn in your license and go back to 27MHz or GMRS.?
If you think this is wrong, ask Riley or Laura...they've both sent notices to repeaters beaconing IDs , etc. Chris WB5ITT
Hi guys
The SLR5700 has a beacon that it transmits in DMR mode so the mobile and hand held units can synchronize the TDMA time slots and know there within range of the repeater???
|
Re: PD526 Duplexer Tuning
Ignore the first two images close to the top. They are earlier plots.
On Sat, Apr 26, 2025, 11:33?AM Part 15 Engineer < kc8gpd@...> wrote: How does this look? It's a nanovna and nit a calibrated to nist piece of equipment so it's not going to be dead on even when you go through the calibration procedure for the nanovna.
I think this is the best it's going to get.
A number of things: ? - You’re sweeping 30 MHz wide with only 401 points.? You need to either narrow down your sweep just to the range of interest, use more points, or more likely a combination of both.? I’d typically be using a 10 MHz span and 1601 points (I don’t have a NanoVNA, I don’t know what it’s capabilities are).
- Something is either very wrong with the cavity, or the calibration.? It is showing you have 3.129 of insertion loss in the bandpass; it should be about 0.25 dB for a properly-functioning PD526 resonator.? Likewise, at the notch frequency, it’s showing that you have 4.77 dB of return loss – it should be a lot closer to zero.? If I were to take a WAG, you have 3 dB or more of cable loss that isn’t compensated for, and/or something is wrong with your calibration kit.
- No since in working on the full duplexer harnessed together until the above are first addressed and you know each cavity is properly tuned individually.
? --- Jeff WN3A ? ? Here is the plot for a single cavity. ? Ok, I'm tuning the pd526 on the nvna. I can't seek to get everything to line up on both reject and pass simultaneously. It seems to be one or the other. I have attached pic of my latest plot. This is the best I got it so far. I did tune cavities individually then hook them together. And I got multiple peaks and valleys on the plot instead on one nice peak on the pass and valley on the reject. Does anyone have a link to the plot for the pd526 and what it should look?like? Thanks
 ? I think I finally got the pd526 tuned. It has 1db difference in sensitivity between direct input and going through duplexer and very little tx power loss coming out of duplexer. Probably only a few watts of loss. Tomorrow I will do some field testing to see if it gets put as far as the txrx 28-70-15h duplexer I was using. I'm not seeing any signs of desense yet. ? It will have the opposite effect.? To get more dynamic range you would really need an amplifier or a way to drive in more signal.? The pads are just to match the impedance as the output/input terminals may not be the nominal 50 ohms.? That is just for the notches.? If tuning the pass with a RLB do not use a pad as this will give a false match/very low RL . On Thursday, April 24, 2025 at 11:28:09 AM EDT, Part 15 Engineer via <kc8gpd=gmail.com@groups.io> wrote: Will a pad give the nanovna more of a dynamic range to see? the notch depth? Iirc the dynamic range of a standard nvna is about 60 to 80db. So if I put a 10 or 15db pad that should help with tuning the notches? ? Pads can be helpful on the generate side of a VNA providing a good resistive match to the device under test. Many years ago working at Hughes Aircraft we always terminated our generate cables with a 6dB pad.?
|
Re: Help with out of range programming a Motorola GP300
Hello Ron,
A couple things here. The "1" in the last of the model number is 433 MHz not 443 MHz. I believe that with the shift method, or hex edit, will only let you go down in frequency, not up.
You also don't say what frequencies you are trying to use.
Mick - W7CAT
toggle quoted message
Show quoted text
----- Original Message ----- From: "Ron via groups.io" To: repeater-builder@groups.io Sent: Saturday, April 26, 2025 08:19:02 AM Subject: [repeater-builder] Help with out of range programming a Motorola GP300 I was recently given a pair of GP300 HTs and am trying to get them reprogrammed for some new hams in the area.
I have the programmer and RSS and can download the codeplug. But,
these are 398-443 MHz RX radios (P94YPC20C1) and won't allow me to put the Amateur repeater frequencies in.
I've tried the Shift key trick when entering frequencies to no avail
(have used this successfully on Radius and GM300 models).? Even tried using a Hex editor and directions I found here to alter the ID bit associated with the model.
Neither works.
Any thoughts on what to try next?
ron
-- Untitled Document
|
Help with out of range programming a Motorola GP300
I was recently given a pair of GP300 HTs and am trying to get them reprogrammed for some new hams in the area.
?
I have the programmer and RSS and can download the codeplug.? But, these are 398-443 MHz RX radios (P94YPC20C1) and won't allow me to put the Amateur repeater frequencies in.
?
I've tried the Shift key trick when entering frequencies to no avail (have used this successfully on Radius and GM300 models).? Even tried using a Hex editor and directions I found here to alter the ID bit associated with the model.
?
Neither works.
?
Any thoughts on what to try next?
?
ron
|
Re: PD526 Duplexer Tuning
A number of things: ? - You’re sweeping 30 MHz wide with only 401 points.? You need to either narrow down your sweep just to the range of interest, use more points, or more likely a combination of both.? I’d typically be using a 10 MHz span and 1601 points (I don’t have a NanoVNA, I don’t know what it’s capabilities are).
- Something is either very wrong with the cavity, or the calibration.? It is showing you have 3.129 of insertion loss in the bandpass; it should be about 0.25 dB for a properly-functioning PD526 resonator.? Likewise, at the notch frequency, it’s showing that you have 4.77 dB of return loss – it should be a lot closer to zero.? If I were to take a WAG, you have 3 dB or more of cable loss that isn’t compensated for, and/or something is wrong with your calibration kit.
- No since in working on the full duplexer harnessed together until the above are first addressed and you know each cavity is properly tuned individually.
? --- Jeff WN3A ?
toggle quoted message
Show quoted text
From: repeater-builder@groups.io <repeater-builder@groups.io> On Behalf Of Part 15 Engineer via groups.io
Sent: Saturday, April 26, 2025 7:46 AM
To: repeater-builder@groups.io
Subject: Re: [repeater-builder] PD526 Duplexer Tuning? Here is the plot for a single cavity. ? Ok, I'm tuning the pd526 on the nvna. I can't seek to get everything to line up on both reject and pass simultaneously. It seems to be one or the other. I have attached pic of my latest plot. This is the best I got it so far. I did tune cavities individually then hook them together. And I got multiple peaks and valleys on the plot instead on one nice peak on the pass and valley on the reject. Does anyone have a link to the plot for the pd526 and what it should look?like? Thanks
 ? I think I finally got the pd526 tuned. It has 1db difference in sensitivity between direct input and going through duplexer and very little tx power loss coming out of duplexer. Probably only a few watts of loss. Tomorrow I will do some field testing to see if it gets put as far as the txrx 28-70-15h duplexer I was using. I'm not seeing any signs of desense yet. ? It will have the opposite effect.? To get more dynamic range you would really need an amplifier or a way to drive in more signal.? The pads are just to match the impedance as the output/input terminals may not be the nominal 50 ohms.? That is just for the notches.? If tuning the pass with a RLB do not use a pad as this will give a false match/very low RL . On Thursday, April 24, 2025 at 11:28:09 AM EDT, Part 15 Engineer via <kc8gpd=gmail.com@groups.io> wrote: Will a pad give the nanovna more of a dynamic range to see? the notch depth? Iirc the dynamic range of a standard nvna is about 60 to 80db. So if I put a 10 or 15db pad that should help with tuning the notches? ? Pads can be helpful on the generate side of a VNA providing a good resistive match to the device under test. Many years ago working at Hughes Aircraft we always terminated our generate cables with a 6dB pad.?
|
Re: PD526 Duplexer Tuning
Your picture tells a lot.? My guess is that the cans on the same side of the duplexer are over coupled because of improper coax length between the cans. In other words, with the proper 1/4 wavelength , a short on one end creates very high impedance on the other end which gives the most isolation or decoupling between cans on the same side of the duplexer. It may only be off less than 1 inch length at UHF.
Since the best return loss perfectly aligns with least insertion loss, the length of coax between the antenna T and the opposite side cans is the proper length, so that is good.
?
John
On 04/26/2025 6:51 AM EDT Part 15 Engineer via groups.io <kc8gpd@...> wrote:
?
?
Ok, I'm tuning the pd526 on the nvna. I can't seek to get everything to line up on both reject and pass simultaneously. It seems to be one or the other. I have attached pic of my latest plot. This is the best I got it so far. I did tune cavities individually then hook them together. And I got multiple peaks and valleys on the plot instead on one nice peak on the pass and valley on the reject. Does anyone have a link to the plot for the pd526 and what it should look?like?
?
Thanks
I think I finally got the pd526 tuned. It has 1db difference in sensitivity between direct input and going through duplexer and very little tx power loss coming out of duplexer. Probably only a few watts of loss. Tomorrow I will do some field testing to see if it gets put as far as the txrx 28-70-15h duplexer I was using. I'm not seeing any signs of desense yet.
?
It will have the opposite effect.? To get more dynamic range you would really need an amplifier or a way to drive in more signal.? The pads are just to match the impedance as the output/input terminals may not be the nominal 50 ohms.? That is just for the notches.? If tuning the pass with a RLB do not use a pad as this will give a false match/very low RL .
?
Ralph ku4pt
?
?
On Thursday, April 24, 2025 at 11:28:09 AM EDT, Part 15 Engineer via <kc8gpd= gmail.com@groups.io> wrote:
?
?
Will a pad give the nanovna more of a dynamic range to see? the notch depth? Iirc the dynamic range of a standard nvna is about 60 to 80db. So if I put a 10 or 15db pad that should help with tuning the notches?
Pads can be helpful on the generate side of a VNA providing a good resistive match to the device under test. Many years ago working at Hughes Aircraft we always terminated our generate cables with a 6dB pad.?
?
?
|
Re: PD526 Duplexer Tuning
Here is the plot for a single cavity.
Ok, I'm tuning the pd526 on the nvna. I can't seek to get everything to line up on both reject and pass simultaneously. It seems to be one or the other. I have attached pic of my latest plot. This is the best I got it so far. I did tune cavities individually then hook them together. And I got multiple peaks and valleys on the plot instead on one nice peak on the pass and valley on the reject. Does anyone have a link to the plot for the pd526 and what it should look?like?
Thanks 
I think I finally got the pd526 tuned. It has 1db difference in sensitivity between direct input and going through duplexer and very little tx power loss coming out of duplexer. Probably only a few watts of loss. Tomorrow I will do some field testing to see if it gets put as far as the txrx 28-70-15h duplexer I was using. I'm not seeing any signs of desense yet.
It will have the opposite effect.? To get more dynamic range you would really need an amplifier or a way to drive in more signal.? The pads are just to match the impedance as the output/input terminals may not be the nominal 50 ohms.? That is just for the notches.? If tuning the pass with a RLB do not use a pad as this will give a false match/very low RL .
Ralph ku4pt
On Thursday, April 24, 2025 at 11:28:09 AM EDT, Part 15 Engineer via <kc8gpd= gmail.com@groups.io> wrote:
Will a pad give the nanovna more of a dynamic range to see? the notch depth? Iirc the dynamic range of a standard nvna is about 60 to 80db. So if I put a 10 or 15db pad that should help with tuning the notches?
Pads can be helpful on the generate side of a VNA providing a good resistive match to the device under test. Many years ago working at Hughes Aircraft we always terminated our generate cables with a 6dB pad.?
|
terry dalpoas
Chris Boone WB5ITT
Marlo Montanaro - KA2IRQ
Hudson, John@CalOES
John N. Hudson III
