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I believe if you are triggering on your reference frequency and the signal you are observing is drifting left it is high in frequency (shorter in time) with respect to the trigger and the opposite (longer in time) if drifting right. Otherwise a great video. I had a M100 running for about 25 years before it gave out. I need to pull it off the bench and work on it. Sam W3OHM

I really want one, but I wish that they added Kenwood's NXDN software, because that want I want.

You'd mentioned bluetooth programming at the very end - can you actually program the VP over bluetooth? My dealer is telling me know, I'd love to know as I've got one on order. EDIT: The marketing material sure says so... I guess I'll have to figure it out.

Can this unit do 800mhz NAS?

got mine tuned pretty good i think, do i need to measure Vswr as well? shows .75 DB

My guy, the RFI shielding can pops you cut in were just perfect! Thanks for the effort and added touch, +1 sub!

Yes need to tweak my pre-selector on my Quantar... Seeing this has reminded me!

good info! KD9YTP

Very good! Keep em coming!

I know what your project is...maybe because I believe you have discussed it on another site but still. I've always tuned these things according to the Quantar Site Manual. Seems to work pretty well. Only catch 22 is I use the tracking generator instead of the method using the signal level and frequency generator. I have so many of those probes laying around from all the Quantars.

Tuning the filter off center is a great way to do this. I've done it several times, and while not ideal for insertion loss/s11, it's about balancing the system. Putting a notch on the transmitters for the receiver frequencies is still something to consider, as all solid state amps will make broadband noise. Fuck those Mini-UHF connectors. The QMA is worse for vibration (mobile) use. I just use a standard screwdriver, the tuning slug is at ground. One of the better ways to tune a many pole filter is in the time domain, if your VNA has transform on it. Not needed with this small filter, but with a 8 pole filter, or some of the 900 MHz stuff, it's needed. On the VHF Range 2 (150-174 MHz), I set the center for 146 MHz and as that's 5 poles, it makes it much easier to tune the range 2 down to cover the ham band. It's about the only way to tune it decently.

Thanks for the shout-out

One of the main reasons for the filter before the first RF amp in the receiver is that the first RF amp generally has a 100+ MHz of amplification. The RF amp has a max total output power, and strong signals will "rob" power from the intended signal, and can cause a weak signal to be covered up due to compression of the dynamic range of the RF amp.

I work with gtr8000 p25 vhf I need some information can you help me please

Can you provide a link to where you got the channel knob that was put on that 8000? I prefer it to the larger knob that I put on mine.

Can it do P25 phase 1 & 2 / analog / DMR and NAS on P25 phase 2 ? Thanks for the videos!

Невероятно полезное и уникальное видео. Искренне благодарю Вас за этот труд!

Due to pressure broadening of the absorption spike, I wonder how much shift is measurable for various elevations from sea level reference?

You must be rich i live in my van and need donations the ways to help are in my about me

I have a EF Johnson 5100es but i need to know how to get it to listen as a p25 scanner

I wanna get one for Free

I couldn't even afford the custom knob... where, pray tell, where people get the money for these???

Which XPR did you have?

Only rich people can afford these radios.

Jeez, dude....isn't there some kind of update you wanted to talk about...?

Well done, and thank you

That's one of my EPROMs. I bet it's just got some oxidation on it. The sockets never go bad, but do come unsoldered due to board flexing over time, as they are surface mount. I'd reflow it. Also discord noises in the background, kek. It's IRC for people to dumb to figure out IRC.

Nice video, but I have couple of notes. 1. You really should have a proper heatsink on the RbO base plate. The base plate temperature should be somewhere around 30-38 deg. C (mine is currently operating at 33 deg. C with passive heatsink). 2. Personally, I am not sure that the idea to put RbO inside the GPS loop is a good idea. I am certainly no time/frequency professional or academic, but I had a rather long e-mail discussion with Brooks Shera (the man, who basically invented the idea of GPS pacification of OCXOs back in 1998) in summer 2000 about this aspect. And his opinion was that RbO is much better to be left alone as a free running frequency normal with excellent short term stability and that the "kicking" of RbO with 1PPS can only make things worse, especially if the time constant of FIR filter is not long enough (typically days or weeks). Same thing is valid when it comes to external steering by some component. Either the multi-turn potenciometer or some DAC. The thermal stability of those components is almost always much worse then the thermal stability of the RbO module without any external stimulus. 3. In my home lab, I am using GPS pacified OCXO (an old HP10811A) with Motorola OnCore UT+ (in position fix mode) built according to the Brooks Shera design - www.qsl.net/n9zia/wireless/QST_GPS.pdf for almost 25 years with only one interruption in 2002 (floods in Czech republic) and even today, the precision is really good. But the short time stability is not so good. So, if I want to measure something with better short term stability, I simply switch on my RbO, wait 3-6 hours or better to next day and do measurements. After this, I switch my RbO off until next measurement. RbO is not like OCXO and it does not need to be switched-on without interruption for decades. It will not become better after ten or twenty years, like good red wine or OCXO. :)

Good stuff!

$50 bucks... these things going for $150 at least on eBay...

I would so love to have one.

What a spectacular video - thanks for putting this together 😊😊

You're Kenwood is Beautiful ❤️

Sub 6k radio and you put a ching dong garbage antenna on it?

I can't wait for you to discover analog audio profile in P25. The salespeople and secretaries thought they were using analog radios.

me when my dealer named 'god' gives 1 mega ohm impendance: yess me when 'god' gives me apple 2gs with dead capcitor again: nooooooo

Can this radio do NAS

What model is the rf dummy load

Has there been any announcement on the software upgrade for NXDN capability? Thank you

Waiting.....waiting....waiting For part 2.

How does the Kenwood compare to the BKR9000?!!

Great video! The attached article is well worth reading. Very similar to calibrating scope probes to your scope with the internal 1 Khz square wave oscillator. W2AEW has a great video on that. I like your style of videos and the way you show your mistakes as well. Also, along with it's intended purposes, a $10,000 service monitor is a GREAT table for storing junk on. Merry Christmas, happy holidays, 73's and all that garbage too.

Cool video! I played around a lot with Rubidiums back in the day when the FE-5680As were cheap and plentiful on eBay. As you know and mentioned, the more references you have, the less sure you are about which one is right. :) Rbs aren't perfect, with good enough equipment you can measure the drift and other weirdness that they exhibit, it's just further down in the noise of most people's test equipment. Getting that hooked up to your GPSDO, especially if you put it on a UPS to ride through power outages, should net you really nice long term stability. The OCXO version of your reference might still be useful if it ends up having lower phase noise. I'm looking forward to the follow up!

I have a similar rubidium oscillator and that also lost sync from time to time. When I attached a heatsink and addad a blower to keep the case cool, it didn't do that anymore. Just make sure the cooling is not too much or the heater will have a hard time...

Very nice video, thank you 😊

what a fascinating video. i have now learned some things. thank you sir. i will hit that subscribe button. hmm my thoughts are that the drift is too much. the rate of rotation of that circle is pretty fast. my thoughts are that a magic cesium clock and gps satellite would not be off by that much. a little bit yeah but not that much

Hello. I have the same model of oscilloscope. It is much better and precise to use 1 and 3 or 2 & 4 channels at the same time. Because of internal architecture of this model of SIGLENT. When you use 1&2 (or 3&4) channels at he same time, ADC works in interlive mode and the real sampling rate is two times lower.

6:50 A-ha! That was on my mind since the beginning of the video - a useful bit of information there, saving us the trouble of finding out ourselves. I guess that makes buying a second hand one a gamble then.

Just a thought. There should be a C-Field trim to bring the frequency in. The hyperfine transition is influenced by the magnetic field and so the C-field trim compensates for this. That will likely be the external trim voltage you will be using your GPS disciplining board to control.