CHP and a 996P2

Paysonscanner

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Try disabling the pl tone on the CHP frequencies and just use carrier squelch.
I use the GRE PSR 500's and 600's for the bulk of my scanning. Years ago, especially in the "CHPERS" days, late Hubby programmed the pl tones on every frequency as shown. He had done so on some BC-760's that he modified for CTCSS operation. He didn't like listening to North Carolina or whatever unless he wanted to. But, the PSR's worked differently and cut off the beginning of transmissions. He then saw someone suggest to another hobbyist to turn take the tone off and instantly we had great reception. He took out all the tones for the CHP in all the multiple programs we had for CA.
 

gmclam

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I use the GRE PSR 500s and 600s for the bulk of my scanning. Years ago, ... programmed the pl tones on every frequency as shown. ... But, the PSRs worked differently and cut off the beginning of transmissions. ...
In the non-dgital models, GRE used a CTCSS/DCS decoder chip. It works wonderfully. In the digital models (PRO-106/PSR-500) they omiitted the chip and used the DSP to decode those tones. I believe they went out of business before finalizing the programming. (otherwise the programming stinks).

To get around the issue, I've modified the CTCSS/DCS decoding parameters in the PSR-500. It's not perfect, but it keeps the radio from missing the first part of a transmission. This is one reason why I prefer the PSR-310 when monitoring analog; otherwise the PSR-500 is stellar.
 

K4RBT

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To properly use a VNA to check antennas, you need to add a return loss bridge. This bridges the input and output connectors and one one connector for the load. It sends a signal out, the antenna reflects the signal which is read by the return port. I was told this by a man who used to manufacturer these (the professional ones, up to 60 GHz). He has one of the mini VNA units as he sold his business to Tektronix. He kept a few pieces of equipment. I ordered one off of eBay that is the original made by someone in the Ukraine. The Chinese ones that copied his are not in a box and have mistakes in the pcb, read the reviews. My Rigol Spectrum Analyzer has one, but it is $700.. Maybe later.
 

jonwienke

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To properly use a VNA to check antennas, you need to add a return loss bridge. This bridges the input and output connectors and one one connector for the load. It sends a signal out, the antenna reflects the signal which is read by the return port. I was told this by a man who used to manufacturer these (the professional ones, up to 60 GHz). He has one of the mini VNA units as he sold his business to Tektronix. He kept a few pieces of equipment. I ordered one off of eBay that is the original made by someone in the Ukraine. The Chinese ones that copied his are not in a box and have mistakes in the pcb, read the reviews. My Rigol Spectrum Analyzer has one, but it is $700.. Maybe later.
Your source is wrong on several points. The $70 VNAs include all the circuitry to correctly measure return loss, and while the first units may have had hardware errors, the ones being sold now work correctly. They aren't as accurate as units costing 10x as much, but are more than accurate enough to diagnose common antenna problems, and to tune antennas for best performance.
 

ladn

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I use the GRE PSR 500's and 600's for the bulk of my scanning. Years ago, especially in the "CHPERS" days, late Hubby programmed the pl tones on every frequency as shown.
I've never programmed pl tones on CHP or LASD when they were on low band. Since it didn't happen too often, I wasn't bothered by skip transmissions. Sometimes it was amusing.

My best DX was on an LA City FD channel (33 MHz range) back many moons ago. Spanish transmision talking about a fire response. I don't remember exactly whee it originated from, but somewhere in South America.
 

K4RBT

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On the return loss bridge, read this:
There is no explaination in the VNA saying anything about a Return loss bridge. My spectrum analyzer, with software, can do what a VNA does and for full testing recommend a RLB. A good wide band unit is about $700 to $1000, that is why most people do not buy them. I have the mini VNA of the latest version and there is no comment on a RLB.
 

jonwienke

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On the return loss bridge, read this:
There is no explaination in the VNA saying anything about a Return loss bridge. My spectrum analyzer, with software, can do what a VNA does and for full testing recommend a RLB. A good wide band unit is about $700 to $1000, that is why most people do not buy them. I have the mini VNA of the latest version and there is no comment on a RLB.
The $70 VNAs measure both SWR and return loss with reasonably good accuracy, without any additional external circuitry. You're posting misinformation.
 

K4RBT

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I have not seen any VNA that states it has an internal RTB. What model do you have? The menu in mine says nothing about it. I bypassed all of the vendors selling on Amazon as I keep reading bad reviews. I bought mine direct from China. I looks similiar, but has extensions of the case to protect the SMA jacks. Also has a larger screen. No magnifier needed, a fault of aging, poor eyesight.
The person I referred to has a lot of top of the line Agilent, Tectonics, and others. His bench unit is not a VNA, but full blown Network analyzer.
He has a PHd in electronics and every question I ask, he usually refers me to sources to find the answer. I guess because it is easy to answer, but you learn nothing. The book recommended for cavity filters is a College text book, $150 used. But it was worth it, I got my answer and more.
 

Mike_G_D

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VNA = "Vector Network Analyzer"

A "VNA" IS, by its very nature, a "full blown Network analyzer"!

I have worked with a lot of HP/Agilent two port lab desktop and rack mount VNA's, most that costed as much as a small or medium size house at the time.

Never used nor needed a "Return Loss Bridge".

For a single port device, like an antenna, you would just use one port, calibrate it with an open, load, and short including the test cable to calibrate that out of the measurements and then attach to the antenna. Preferably the antenna would be mounted away from any metal or otherwise RF conducting objects (including people, trees, etc.) and on a suitable ground plane if the antenna design warrants it.

I've never used the new small cheap Chinese VNA's but from looking at some pictures and brief descriptions they seem like min-sized real two port VNA's albeit with, perhaps, questionable accuracy and maybe long term reliability but, given the insanely enormous price difference between them and what I used to use probably just fine for non-critical hobby use. Given my lack of funds and strong desire to play with one I may well wind up buying one in the near future.

-Mike
 

K4RBT

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When you use the return loss bridge, you just do not check the antenna, but feedline and connectors. Sure, I put two antennas on just the VNA, saw resonance, but no return loss. Return loss is similar to VSWR, You can tell where in the feedline there is a discontinuity, like a bullet crease in Heliax (been there done that sometimes at night when visual is impossible). Now the top dollar units I looked at on eBay, do not say Vector, just network analyzer. Now, the main reason I purchased the VNA is to have something portable to system check an antenna install. People put cables in vehicles where they have not checked the path. Car manufacturers leave sharp edges from stamping body parts. I have cut myself just being under the hood (Oh, how I miss my Motorola fender cover) and it literally shaved the skin off. Pull a cable across this and shave the cover off. That is why I no longer do installs unless the vehicle is pre-1970, just to dangerous.
 

jonwienke

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I've never used the new small cheap Chinese VNA's but from looking at some pictures and brief descriptions they seem like min-sized real two port VNA's albeit with, perhaps, questionable accuracy and maybe long term reliability but, given the insanely enormous price difference between them and what I used to use probably just fine for non-critical hobby use.
That is exactly what they are. Same functionality as a full-price VNA, but, less accurate, and less robust build quality. Plenty good enough for hobbyist purposes, though.
 

jonwienke

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When you use the return loss bridge, you just do not check the antenna, but feedline and connectors.
You don't need any external bridge circuit to do that. The VNA has that functionality built in.

I have one of the $70 units, and have used it to check cables and connectors as well as antennas. It can even measure the length of cable or the location of a short/open, if you know the velocity factor of the cable.
 

Mike_G_D

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Trust me, I don't always agree with Mr. Wienke but in this case, I do, pretty much 100%.

A "Vector Network Analyzer" is as opposed to a "Scalar Network Analyzer"; the former looks at BOTH the magnitude AND the phase of the reflected signal versus that of the incident signal and bases its results on the difference while the latter looks at ONLY the magnitude of the reflected signal versus that of the incident signal and, again, bases its results on the difference.

In both of those devices the results can be computed and shown in many ways including VSWR (a VSWR meter is a very specific and simplified form of a Scalar Network Analyzer) but a VNA is MUCH more telling and flexible. Knowing the phase of your reflected signal relative to the incident given a normalized calibrated origin point (usually 50 ohms resistive for most RF testing) can tell you exactly in which "direction" (a loose analogy) to "tune" for in terms of capacitive or inductive reactance to add to in a matching circuit or for lengthening or shortening an antenna element.

As for "feedline and connectors", yes, well you definitely want to check those but it's always best to do those as separate tests. Feedlines can be measured in a two port analysis using S12 and S21 measurements and connectors can be part of that feedline, usually. For the test lead to the antenna (or whatever single port "Device Under Test" or "DUT") you use your calibrated test cable, preferably, and run your open, short, and load calibrations with the cable in place to effectively make the test lead "invisible" to the final results for the single port DUT.

Anyway, went beyond what I think is needed here, but the idea is a VNA is absolutely a "full blown network analyzer" and, while a "return loss bridge" may be required for some older forms and for devices not actually intrinsically network analyzers (such as using a spectrum analyzer and a tracking generator) modern full featured VNA's already include that functionality built in. It doesn't need to be mentioned in the documentation because you now only need to focus on the actual one and two port S parameter analysis, S11, S22, S12, and S21.

-Mike
 

com501

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Did anyone check to make sure the OP had is receiver set for FM and not NBFM for low band? That would screw up the signal.

OTOH, my 'cheap' VNA works great, but lacks the 100db plus range of my (Used car priced) HP VNA.
 

amoking

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problem fixed with new BNC even though it tested out good with a multimeter. Thanks for all the ideas and suggestions.
 

amoking

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From the tri-valley with an NMO40 antenna on my truck I can clearly get Solano to Oakland to San Jose to Stockton. When on I-5 in the open it's further.
 
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