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In case you thought I made that up. Just closing now.

In my "previous life", I did take a job where I was responsible for "finishing" the previous guys "big idea for a QAM-64, 12.5 kHz receiver". That "big idea" took him out and I was able to get that done and eventually passed by Part 90. Yes, I am the first guy to get a high-power QAM-64...

The bandwidth is actually very high for "narrow band" communications. This product (that I designed) allows for the maximum allowed bandwidth allowed by the FCC. In almost all cases, the bandwidth is limited to 12.5kHz. With the 220 MHz band, it is limited up to 50 kHz bandwidth just like the...

Ok, I guess I'm "allowed" to post in this thread, but not other theads. lol. Anyway, please send me a screenshot of the device manager after you plug the device in?

Could've been a MAX737?

Let's see if we can do that without 10 pages of CIA "white space". I would like to add some perspective. Like many others before me, I designed telemetry to track a balloon system that reached > 100k ft. During the assent, the balloon will move around with the atmosphere (obviously). Once it...

I apologize if my previous response was confusing. I thought you were posting with sarcasm regarding how hard it would be to actually get images of a balloon at 90k ft. That is really up there! At that altitude clouds and their respective shadows look like they are almost touching the earth.

I would like to add some perspective. In the past, I designed telemetry to track a balloon system that reached > 100k ft. During the assent, the balloon will move around with the atmosphere (obviously). Once it gets above a certain altitude, the atmosphere no longer affects the position of the...

Sounds plausible to me.

If only the earths rotational velocity were much slower.. The classified scandals will still be there after the earth moves further west underneath it. lol.

Thanks for reporting your findings! Looks like USPS expects to deliver the passive 770 MHz filter today.

I designed the model 195H hardware / firmware. It doesn't do P25, but does do 217-220 MHz narrow band over Ethernet/RS-232/RS-485/RS-422. https://www.esteem.com/wp-content/uploads/195H-Narrowband-Product-Sheet.pdf On the topic, I've never seen P25 in this range yet.

@brndnstffrd , I forgot to mention you in the previous reply from last evening. Let me know if that driver works on Win 7 / MicroP25RX when you have a chance. If it does, I will put a reference to it somewhere on the download page.

lol. So your advice is that it is ok to run without a preselect filter at all? After you incorrectly trashed my design over and over for this? Even after I told you multiple times I had a pre-select filter on there? You think designing a narrow bandpass UHF filter is easy, but you admit you are...

That amp has a very average/low OIP3. A nearby LTE tower is going to hammer it. A good rule of thumb is to look for an amp with an OIP3 20-25 dB above P1dB compression.

This is not tested at all, but see if this MicroP25RX BTT driver for Windows 7 will help. Please use this file to install a driver when prompted. https://cdn.shopify.com/s/files/1/0289/8224/7521/files/micro_btt.inf?v=1675309149

Thanks for the honest review! Note that the 2nd filter (still in transit), the passive 770 band-only, will have much better stop-band attenuation, but will limit you to monitoring the 770 band only. The SELECT-78 filter has less stop-band attenuation due to the way that the dual band pass...

@pcman67 provided pre-compiled versions of MicroP25RXMon for the Mac. They are available on the website for download here: https://bluetailtechnologies.com/pages/microp25rxmon

Glad to see that it is working for you. The second (passive) 770 filter is on the way to you. That filter will give better stop-band attenuation, but you will lose some sensitivity unless you place it after the SELECT-78 filter/preamp. Either way, it looks like both solutions will work for you...