Not for high voltage, but for fire alarm cabling on utility poles.
I had a Riser Bond TDR that I used for fault location.? A long time ago I was asked to find a fault in a municipal cable that was once used for fire alarm call boxes.? The fault was an open circuit.? One of the things that you have to take into consideration is the velocity factor of the cable that you are troubleshooting.? This is usually impossible to know.? So I used another method.? I measured the fault from either end.? Just for a theoretical example, the TDR measurements were 1000 feet and 500 feet.? The actual physical length of the cable was 1000 feet. Interpolating that, the fault was 666 feet from one end and 333 feet from the other.? Sure enough, we found the cable had visible physical damage at this distance and fixed the problem.
I've never done underground TDR testing, but the same method should apply.? If it is a single hard fault (open, short) you should be able to find it.? Multiple faults could be very hard to find.? Be careful of any stray voltage on the cable, as it can damage the test equipment.? We had an Hewlett-Packard TDR test set that was damaged by voltage on the cable.
Joe, K1ike
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On 4/7/2025 11:38 PM, Karl Shoemaker via groups.io wrote: Anyone have experience using a TDR to locate an underground fault for high voltage ?
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Re: Possibly Quintron PA? Need help identifying transistors
Quintron made a lot of equipment for the 72-75Mhz linking band for paging.
Joe, K1ike
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On 4/8/2025 9:00 AM, Jeff DePolo WN3A via groups.io wrote: I’d have to think it’s highband or midband.
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Re: MTR2000 channel steering
Mornin' John,
> I'm trying to program channel steering in the RSS using GPIO
pins on the 96-pin connector without any optional cards.
In the MTR2000, the GPIO pins on J5, the 96-pin System Connector
only connect to J1 and J2, the Option slots in the cardcage.? The
System Controller is at J3.? To use those pins requires an Aux I/O
See the connector table at:
The To/From column shows where the signal connects.
73,
? Dave
On 4/8/2025 6:55 AM, john ni0k wrote:
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Chris,
I'm trying to program channel steering in the RSS using GPIO
pins on the 96-pin connector without any optional cards. That
section of the RSS isn't very straightforward to me.
73
-de "Curly" John NI0K
call me: 6100271
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Attached is some information on the DB212 antennas.? Perhaps this will help.? This was factory info from a DB212-2 that was tuned to 47.14 MHz. 73 Joe WB4HIS ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Roger willey via groups.io
Sent: Tuesday, April 8, 2025 09:28
To: [email protected]
Cc: [email protected]
Subject: Re: [repeater-builder] 6 m repeater antenna? ?
On Apr 7, 2025, at 5:55?PM, wgwl via groups.io <wgwl@...> wrote: ? Roger,
In hopes of answering your original question, I got my hands on a DB212-2 originally on 37.7MHz and shortened the antennas and matching section for 6?
meters. The 35 ohm matching section (Decibel Products VB-83 cable) was shortened?
to 36.25" end to end. With a UHF T on the end?
and two 50 ohm loads attached resulted in the attached plot. As you can see, the?
exact length is not critical across the band. John,
You mentioned "DB factory lengths" in an earlier post. Do you have access to the?
actual factory length chart for 6M ? If so, please share. How well did the tuning of your antenna on the ground translate to mounting on a tower? What length of pipe did you use when tuning? <6meter DB212-2 matching section.png>
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On Apr 7, 2025, at 5:55?PM, wgwl via groups.io <wgwl@...> wrote:
? Roger,
In hopes of answering your original question, I got my hands on a DB212-2 originally on 37.7MHz and shortened the antennas and matching section for 6?
meters. The 35 ohm matching section (Decibel Products VB-83 cable) was shortened?
to 36.25" end to end. With a UHF T on the end?
and two 50 ohm loads attached resulted in the attached plot. As you can see, the?
exact length is not critical across the band.
?
John,
You mentioned "DB factory lengths" in an earlier post. Do you have access to the?
actual factory length chart for 6M ? If so, please share.
?
Mike,
How well did the tuning of your antenna on the ground translate to mounting on a tower? What length of pipe did you use when tuning?
Greg
WB9TRO
<Matching Section.jpg> <6meter DB212-2 matching section.png>
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On Apr 7, 2025, at 5:55?PM, wgwl via groups.io <wgwl@...> wrote:
? Roger,
In hopes of answering your original question, I got my hands on a DB212-2 originally on 37.7MHz and shortened the antennas and matching section for 6?
meters. The 35 ohm matching section (Decibel Products VB-83 cable) was shortened?
to 36.25" end to end. With a UHF T on the end?
and two 50 ohm loads attached resulted in the attached plot. As you can see, the?
exact length is not critical across the band.
?
John,
You mentioned "DB factory lengths" in an earlier post. Do you have access to the?
actual factory length chart for 6M ? If so, please share.
?
Mike,
How well did the tuning of your antenna on the ground translate to mounting on a tower? What length of pipe did you use when tuning?
Greg
WB9TRO
<Matching Section.jpg> <6meter DB212-2 matching section.png>
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On Apr 7, 2025, at 5:55?PM, wgwl via groups.io <wgwl@...> wrote:
? Roger,
In hopes of answering your original question, I got my hands on a DB212-2 originally on 37.7MHz and shortened the antennas and matching section for 6?
meters. The 35 ohm matching section (Decibel Products VB-83 cable) was shortened?
to 36.25" end to end. With a UHF T on the end?
and two 50 ohm loads attached resulted in the attached plot. As you can see, the?
exact length is not critical across the band.
?
John,
You mentioned "DB factory lengths" in an earlier post. Do you have access to the?
actual factory length chart for 6M ? If so, please share.
?
Mike,
How well did the tuning of your antenna on the ground translate to mounting on a tower? What length of pipe did you use when tuning?
Greg
WB9TRO
<Matching Section.jpg> <6meter DB212-2 matching section.png>
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Re: Possibly Quintron PA? Need help identifying transistors
It definitely looks like a Quintron constructed board.? The white label with the writing on it looks like how they identified boards. The date code may be 1989?? I think that was before they were bought out by Glenayre.? I've worked on several pieces of Quintron/Glenayre equipment but don't remember this board, especially one that had a BNC pigtail on it.? The pigtail looks like it was factory installed and not a modification, unless someone did a nice job of modification.
Joe, K1ike
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Re: Possibly Quintron PA? Need help identifying transistors
Anything with an SRF part number is usually a special-production or binned version of a regular MRF part, but rarely were cross-references (if they existed) published.?? That said, given the amount of inductance in the matching networks, I’d have to think it’s highband or midband. ? ??????????????????????????????????????????????????????????????????????????????????????????????? --- Jeff WN3A ?
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From: [email protected] <[email protected]> On Behalf Of Tyler- WZ5TX via groups.io
Sent: Monday, April 7, 2025 9:29 PM
To: [email protected]
Subject: [repeater-builder] Possibly Quintron PA? Need help identifying transistors? I have this PA and it is labeled “100W PA”. However I cannot find the datasheet for the transistors. Motorola SRF2604. any ideas what the range for this is?
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Re: MTR2000 channel steering
Chris,
I'm trying to program channel steering in the RSS using GPIO pins on the 96-pin connector without any optional cards. That section of the RSS isn't very straightforward to me.
73
-de "Curly" John NI0K
call me: 6100271
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Re: Suggestions for service monitor
The Motorola 2600 series is hard to beat... And can be found reasonably priced if you are patient.
Mike,
This is a Windows program, but I think it's a lot of what you want and you can choose the hardware
?
Steve N4IRS
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Re: Suggestions for service monitor
Mike,
This is a Windows program, but I think it's a lot of what you want and you can choose the hardware
?
Steve N4IRS
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Re: Possibly Quintron PA? Need help identifying transistors
WZ5TX
David “Tyler” Bufkin
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Well here's an idea, put 12 volts to it, put a service monitor or signal generator into it, broadband watt meter on the output and sweep it and see where you get a peak in RF out driving it with say +10dbm... Probably won't see a hundred Watts
out with that drive but it'll tell you what band it is.
"There are always possibilities"
Famous Vulcan saying
Chris WB5ITT?
Here is a pic of the only numbers I see on the board.
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Re: Possibly Quintron PA? Need help identifying transistors
Well here's an idea, put 12 volts to it, put a service monitor or signal generator into it, broadband watt meter on the output and sweep it and see where you get a peak in RF out driving it with say +10dbm... Probably won't see a hundred Watts out with that drive but it'll tell you what band it is.
"There are always possibilities" Famous Vulcan saying
Chris WB5ITT?
Here is a pic of the only numbers I see on the board.
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Re: Possibly Quintron PA? Need help identifying transistors
Here is a pic of the only numbers I see on the board.
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does anyone have a programming lead for a kyodo kg510 or schematic of one
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Re: Suggestions for service monitor
Third.
Bob NO6B
At 4/7/2025 03:47 PM, you wrote:
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I second this. I had the same
question about a month ago and ended up getting an HP8921A. It?�?s a good
analyzer to learn on and does probably way more than you need.
On Apr 7, 2025, at 6:42?�?PM,
Mike via groups.io <prcradio@...> wrote:
???
For non digital stuff the HP/Agilent 8920 series.
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Re: Capacitors in DB4332B and DB4333B
Alex:
Thank you for these pictures. This is very helpful information. I
have a Johanson catalog and tried to match the capacitors at least
in physical size.? It did occur to me the capacitor values might
be 0.8 to 10 pf. because I think that is the same value used in
the DB4076 duplexers.? The capacitor in the 850 MHz LPF are the
physical same size, but that is all I can say. It looks like DB
broke off the little lug on the end since they soldered to the top
of the capacitors.
Your construction is very well done. The wire in the UHF LP is
insulated magnet wire and is 1 mil in width and I figured that was
18 AWG.? The wire in the 850 LPF is just bare wire, but also 18
AWG.
The coil in the UHF LP had been slightly pushed down in the UHF LP
case and it made me wonder if that was done to change the value or
to help the return loss.? But the wire looks a little long and
they pushed it down to get it away from the lid.? Your neat work
suggests that deformation? is not necessary.?
If the capacitors in the 850 LPF are not the same capacitor values
as the UHF, I did see some of the values you mentioned? on eBay.?
I have two of those 850 Mhz LPF's and one looked fine on the
spectrum analyzer, but the other did not. This makes me think some
of the capacitors in the one with the bad curve are broken.? So I
may be buying capacitors from the listing you suggested anyway. I
will know if the capacitors are the same when I put the coil in
the good LPF.
The only difference I had was that I tried to measure the coil
diameter and got it roughly at 1/4"instead of 7/32". I have some
18 AWG magnet wire here at my office and was going to wind it
using a drill bit as a form.??
Thank you Jeff for your suggestion of using a single piece of
wire. That sounds like a very good idea and I am going to try
that.? I was not going to disturb the connections from the input
to the first capacitor or the output to the last capacitor, but
may go ahead and wind it all as a single piece as you suggest.?
The coils for the 850 LPF are a single piece of wire zigzagged
across the four capacitors.
Thanks again.?
Micheal Salem N5MS
On 4/4/2025 11:28 AM, Alex wrote:
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About 3 years back I had one DB4332-B UHF low pass filer but needed two, so decided to reverse engineer it and build a clone. The variable piston capacitors are Johanson 0.8 - 10Pf rated at 150V. Back then I found several sellers on ebay offering them, and there was one selling them in 4 packs for $25 plus some shipping. The trimmer cap model I used was PC25J100. The model is stamped onto the top solder side of the cap, so usually not possible to see in the original LPF. Just checked on ebay but original listing is gone, however looks like listing #256220267439 is the same guy still offering those trimmer caps in packs of 4 still at the same price.
The 3 coils are made of #18 wire, one side being 2T, the middle one 3.5T and the last one again 2T. Coil diameter is 7/32 or about 5.55m, stretched out same as the original coils.
I also managed to find on ebay someone selling the identical metal boxes (Pomona model 2413) for $10-15 new old stock in the original bag and with connectors on each end, but these instead had one SO-239 and one PL259, which both where very easy to replace with NM/NF. I then also had to drill the four holes to mount the trimmer caps and assemble everything. The clone LPF was then checked on a VNA and compared to the original DB4332 and it had basically identical characteristics as the original one, and of course also tuned up just fine.
About a year later after that I needed two additional UHF LPFs and did build two additional clones that also worked perfectly. The attached picture shows the original LPF at the top, and one of my clones in the blue box at the bottom.
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Anyone have experience using a TDR to locate an underground fault for high voltage ?
There's a PUD in central Washing that can't appear to fix an outage for the past three weeks or so.
It's affecting several comm sites and one ski area. It's high up around 7,000 ASL with 20-foot drifts. ?The road is derivable around the first or second week of July each season.?
?
I'm not sure if it's incompetence or lack of training but the concept seems simple enough to me; send a pulse down the line and watch for the return indicating something is wrong.?
There are several of these units on the market, on line.?
?
I also suspect it's not an exact science and requires lots of experience to be effective.?
If I were in the area I suppose I could hook up the (dead) line to a spark plug circuit (from an engine or whatever) and walk the mile line listening for anomalies with an AM radio.?
For now, one leasee is dragging large amounts of propane to keep one site alive.?
--
-
Regards, Karl Shoemaker
To contact me, please visit SRG's web site at?
for the current email address.
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Re: Amphenol Old Style RG-393?
I think you guys figured it out. It is 0.43 outside diameter and looking up RG-225/U yields the same cable that I have. The cable I have has absolutely no markings on it. The only reason I know it was made by Amphenol is because there was a ribbon on the spool saying "Amphenol Electronics Corporation" on it. It has a single layer of outer woven braid from what I can tell.?
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Dave WA1JHK
Steve N4IRS
Chris Boone WB5ITT
Karl Shoemaker