simonthewizard

President Grant II (V1) No Noises

I really think this morning the radio medicine does not work anymore. Below is a strange tail of an initial release v1 President Grant II eBay purchase and it comes no noise but another radio from the same series shows S7 like it always did. So sit back and indeed this is a 2014 initial release Grant II noise free from the box or so it appears 


So I thought I’d try the noisey Grant II on the DSP and see what happens. I have my initial one and then this one via eBay an a V2 which had SSB in the UK mode first for looking into and below are the findings.

First radio in export mode shows S5/7 noise in all modes in export mode so I returned it back to multi norm to prepare a video and while doing this I changed to the eBay radio, same version 1 big sticker on the top and came in multi norm setting and was noise free. So, checked all the cables, changed the antenna cable in case, patch lead, disconnected filter and tried again and no noise. Connect the first radio and S5/7 noise is there, swap again and nothing at all. So now rU the radio with the sticker and try again and absolutely no noise at all! Connect the first and S5/7 noise. So take a look at the insides of both and no modifications have been made, both same power, board and components the same. Just the eBay one has little blue dots of ink on some components and the other does not.

Now on the noisy radio cannot hear anything below S5 and on the other one can hear signal 0/1 as long as the audio is there. I changed cables, power supply, checked the antenna and all stuff. It is sure the radio is no noise! So I can only conclude that the “Initial release of the Grant II did come noise free” but I’ve just 1 piece from 6 here that is noise free.

Changed:

Coax, disconnected TVI filter, swapped patch lead, checked antenna on analyser all showed to be ok and correctly working

Radios:

Grant II Iniital Release (oldest one I have) S5/7 noise all modes

President Grant II Initial Release from eBay no noise, just usual coughs and splutters

Grant II Premium first release S6/7 noise all modes

Grant II Low Noise Premium S2/3 noise

Now to the smart ones to tell me what happened? Is it a lucky noise free or did some come noise free initial release 

I’ve tried a swap with Tim in Germany, mine was noisy here and quiet with him, and his quiet one was noisy here. Tried in total six Grant II radios either V1 or V2 with uk in SSB mode and all noisy. This is truly the first noise free I have seen from the box from 2014

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4 comments

  1. One other question,are the base antennas your doing your tests on DC shorted\grounded?

  2. Some things come to mind Simon,Im basing this on my knowledge
    from my electronics experiences in the radio industry world and manufacturers I have worked with in past and present.
    It may not bear anything on your radio at all.

    1.Some ones been inside it and re-tuned it?
    2.Some ones modified it,maybe just a SMD part hence why not obvious?
    3.A different batch of SMD parts were fitted either correctly or incorrectly on that production run at Factory?
    4.The next run of batches after this radio had incorrectly loaded smd parts on spools and the rest were all screwed up and left factory and that’s when problems started appearing? (i have seen this in manufacturing first hand and they keep quiet)
    5.It maybe a Fatory special,I have come across these too that get sold off normally via an employee or ex employee who was a technician or got the radio from some in tech\R&D labs at the Factory.
    6.You just got a good one!

    One test you could do if available and someone willing to help you local
    get it on a signal generator or RF comms-test set IFR 2995 of similar,and check/compare it to a newer or noisier unit.
    Do this on all modes and make a table up.
    Check sensitivity,AF distortion,SINAD,S\N,AGC action\ dynamic range and signal handling from +10dBM to -100dBm.

    With those checks an engineer would maybe able to give you some technical differences,is they someone local who could do that for you Simon?
    It may help you a little to get down to the bottom of this in a more controlled test manner.

    I do have one more idea not completely related,but would need to know are you using a Switch Mode Power supply or a Linear PSU Simon?
    Reason I ask I’ve come across some very strange things in my line of work recently on a very sensitive industrial instrument.
    It caused us some right headaches due to SMP used and grounding, that’s has not been document very well or not at all in the power supply industry that could well affect RFI noise in a strange way.
    It was cured after I had a bright idea and yes I have recently applied the cures to my radio ones and how antenna system is DC grounded and surprise less noise and some other benefits.
    Can discuss this in a separate email if you want.

    Glad your Grant II is quiet,have fun 73’s

    Regards

    Rob

  3. Hi
    Those “blue dot” components is really interesting! None i have looked have had them. In which kind of components and where?
    Could be different component values. Could be bad component tolerances. But every Grant i have tested is the same no matter if its on CB on Export mode. With new radios they do the main frequency job in pll chip so couple MHz makes basically no difference.
    Especially v1 Grant has a poor rx front end. In premium they added some filttering etc. Basically, in theory, front end should be fine but in practise there must be some issues. I have had great results by simply changing C26 to for example 39pF and add an adjustable coil after that. C26 is the last capacitor untill it separates to am/fm and ssb. Not much but some adjustability which brings great results.

    Would be really interesting to look into Simons noise free version. Those blue dots.. There is some variance in S-meter between some units but not much. Basically, do not ever look into Grants S-meter like its the truth (like in any radio). Instead, compare signal you hear. Grant 2 v1 has lazy meter on ssb, am/fm is bit sharper. First Premium has close to what it really should be (ie 0.2uV should be S2 and its really tiny signal!) but its over all too sensitive and Premium has again a really lazy S-meter. Interesting things…

    Greatings from Jukola! World famous midnight orienteering event in Finland.

    -Petteri

  4. a great test as they were made and got into the next version was released they have used cheaper components there
    for some were very good and the cheaper components were crap a way to save money on costs but turned out to be very bad for noise and if they are left as the come a multi mode cb great but when they are opened up to more freqs it lets the noise in so best left as a multi band cb and no noise

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