simonthewizard

Today’s Open Letter Is To President! Tomorrow Uniden Open Letter Is Published

It is November and “we will call it interference month” below is the detailed explanation how to make a Grant II have less noise. You’ve all seen the video, Uniden has as the IP address shows up in the stats. So, Dear President can you copy the below information in one of the service teams and see if it works for you?

 

Already people inform me that the company doesn’t care at all for customers, and it’s all profit and no care. Sure it is a business and needs profit, obviously. But I think they will at least read the article (maybe)
Really simple and sense idea which make wonders: Reduce RX front stage gain and increase gain after the signal is filtered.

You really dont need much gain in front stage especially these days when interference and noise is a big problem. Also NB cirsuit in Grant 2 cannot handle strong interference. When you take some gain off from front stage it has to be increased in some place mainly for FM. FM discriminator needs sufficient gain to sense frequency changes properly so..

R5 goes 470 to 10k trimmer pot. R48 goes 1k to 1k trimmer pot. Find the adjustments w/ sinald meter. R5 is not so critical, about 2.5k but after that you have to find a sweet spot with R48. Something around 30-60ohm. In addition you can tweek AGC. Maybe R57 10k to 15-20k, not neccessary. If you change R57 the you can consider to reduce R134. It’s all about bench work, no direct advises since each radio is individual.

After the rx/agc mod you need to make S-meter adjustable. Remove D22 and replace it with germanium or shottky diode which have potential about 0.3V. Original is about 0.6V. Add 10k trimmer pot to anode side of diode and solder to original place. Now S-meter can be adjusted 50uV is S9. After that 160uV is S9+10dB, 25uV S7-8 and then it decreases dramatically. But who cares, it works. And much more like in older President radios.



So, we will see what we will see. President in my opinion do listen. Guess this time they won’t. But tomorrow it is Unidens time in the lights. They design the stuff with President some in turn they need to explain why. I’ve had enough emails about this, I’m not a call centre, I’m not paid customer service President either. So with this in mind November starts the “kill the noise” month.

And Low FM Audio?

Or as one person told me “Send all the radios back to dealers as not fit for purpose then sit back and see what happens” hmm, ideas ideas.

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2 comments

  1. Hi simon,ive studied the schematics and seems no high q tuning coils in rf front end,1st if stage all broadband design .high gain only needed in nfm mode.
    Rx sensitivity is too much you only need typically 1-0.5uV pd on am\ssb due to s\n
    Agc should cope +10dBm to -100dbm for 3db (6dB acceptable)change in audio output @30% mod.
    Rf front end needs hi-Q front end coils not broadband frontend,same in I.f stagestage,will tighten up skirt noise.
    If you want wide band put high Q coils and tracking frontend to help reduce noise floor and have higher selectivity.
    If you have too much overall gain,agc can pump,ANL is less effective.
    Put a 15khz roofing filter crystal after mixer stage to help clean up noise on IF skirt and use proper tunning canned coils to keep Q tight.
    Pin diode by-pass the rf front end for ssb\am by-pass button to help user reduce local noise QRM.
    I think the rf engineers need to go back to drawing board and have a good look at the design.
    Big question is will customers pay more for extra hardware to get this right ?
    and why was it these radios were not field tested to see if issues did show up,prehaps they were and fell on def ear syndrome,i have seen this in manufacturing work place on quite a few radio projects i have professionally worked on ,caused many argument’s in board room by management and rf engineer’s who know there stuff.
    Can be very frustrated when you know some products get released on market technically flawed.
    President need to step up and do in house testing and get them out to dealers for field tests and feedback reports.
    Dont souly relie on the china factory reports and tests on the bench only and a quick 123 on mic tx test.
    Good luck on this quest Simon

    • Hi Rob. Many have asked me via email and message why the noise etc and I cannot actually avoid asking anymore.

      Of course I’m lucky as Uniden and President read the blog, as can see via IP (today 45 hits Japan for example)

      We need to give time now and see what happens. Not really a quest as such, just wanted to answer some questions that I don’t know the answer too. Uniden and President have a long pedigree of good stuff. So we must allow them time I guess.

      Hope your well and thanks so much for writing.
      Regards
      Simon

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