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Palomar Electronics Max-Mod. Spoiler alert!

Discussion in 'CB and Export Equipment and Accessories' started by nomadradio, Jul 9, 2017.

  1. Radioman56

    Radioman56 The Electronics Guy

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    Thanks for making me aware of the "TinyCad" source. (y) It's just that over the years, I've come to discover a few GREAT little (and VERY useful.!) free AND safe programs, such as (but certainly not limited to.!) "Audacity"., "MP3-Gain"., etc. :) Never knew they were just a repository for disseminating such programs :eek: I guess there're sort of like a downsized / smaller version of "CNET".?? :rolleyes: But I certainly do appreciate, and find VERY useful (for most simplified applications) that TinyCad "share-ware".! :D


     
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  2. LeapFrog

    LeapFrog Wielding Hanlon's Razor

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    Demonstrate your claim, it's that simple.
    Prove it, you show me how a failed regulator causes driver & final to "detonate" due to "battery voltage". *(I did it for you)

    Bypassing fuses and removing reverse polarity protection diodes won't help in preventing catastrophic failures.

    Let's all pretend the radio in question is a Galaxy DX66V and TR51 (PNP A.M. regulator) has failed short circuit, has any path to ground presented itself?
    R246 and R245, & possibly through R6 and R7 (near Q3) on the dimmer PCB as well.

    So you've effectively shorted the input of the radio (through R245, R246) and this can burn out the driver & final (by an emitter-to-collector short) if you don't have a reverse polarity protection diode (D93) installed, this whole shtick is very telling.

    So now my question becomes: "Why is your tech removing the RP diode?"
     

    Attached Files:

    #92 LeapFrog, Sep 3, 2019
    Last edited: Sep 3, 2019
  3. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    I just read 7 pages ... WHEW - but no one caught this stat...

    Per @rabbiporkchop post of the spec sheet...

    This stat bothers me...
    PalomarEmitterToBase.JPG

    There are different ways of using transistors to share loads...

    One type is called Darlington and is a basic one drives the other with the output of the bigger one used as feedback for linear or analog operation -

    But you can also use this as a means to drive using SOURCE - and not necessarily as a regulator - only a follower - but the Bigger guys' output is not used as a feedback principle - the non-linear is SOURCED thru a limiter resistor and hence the Gain is also affected...


    Atypical AM regulatorcomparison.gif

    The REGULATION is still there, you only are subbing in a part that simply sinks current thru the base - now I do not know of the use of NPN - but to have an Emitter to Base Reverse Breakdown of 8 volts - that means the PNP/NPN diode "appearance" to ground - relative to DC - is different than a simple BJT bi-polar - it indicates two devices in a single package integration, if the specs are correct to the 8 volts - NOT 0.8 Volts.

    Interesting...
     
  4. blasphemy000

    blasphemy000 Active Member

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    The 45-50W dead carrier would be with a dual final Mosfet chassis. A dual final bipolar (1969/2312) won't do that much with a shorted regular, probably 35-40W, and something like a single final 66V will probably only hit 20W in that case. Keep in mind in AM mode with a full 14 volts on the finals, it will be driving the last stage far into power saturation.
    Yes, quite a few of the old Cobras completely bypassed the regulator in SSB mode. I wish newer radios did that to eliminate the small amount of loss in the regulator when it's fully on. I'm working on a, "just because I can," project to completely eliminate the regulator from my Connex 4400 Turbo. It was working fine before, but I got bored and decided that it needed to become an experiment rig. When I get time to finish it, and if it all works as planned, I'll make a thread about it.
    73s
     
  5. blasphemy000

    blasphemy000 Active Member

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    The RP diode does absolutely nothing unless the radio is plugged in backwards, it's irrelevant to this conversation and it would have zero effect with a shorted regulator whether it's in circuit or not. It's before the regulator anyhow. It shouldn't be removed though.

    The combined resistance of R245 + R246 is like 4.8K ohms, that's only about 3mA at 14V. Those two resistors trigger TR53, which activates the AMC system, when the regulator output voltage gets too close to zero. Those won't effect the finals either. For a shorted regular to pop the finals, somewhere in the TX chain, the signal would have to be significantly overdriven. I don't know if it happens in the Strykers or not, but I've never seen it in a ranger chassis. My sample size is only 8 or 10 with shorted regulars, but they all died due to the driver + finals being way over biased. A properly setup radio isn't going to burn the stock regular, I can promise you all that.
     
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  6. blasphemy000

    blasphemy000 Active Member

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    That spec isn't too far off from normal. That's Emitter-Base voltage, which is typically around 3-8V. The Base-Emitter voltage is what's usually 0.6-1V. These are negative because it's a PNP transistor. In this case it means that if the Emitter voltage is more than 8V less than the Base, that junction will break down. Normally for a PNP transistor the Base voltage is lower than the Emitter. It's the maximum spec for a reverse voltage breakdown condition across that junction. Look at other transistor specs, they're similar.
     
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  7. Radioman56

    Radioman56 The Electronics Guy

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    I can somewhat understand why you'd like to eliminate the small amount of voltage loss that can occur through the power-regulator (even when it's in its "fully-saturated" condition) while the RF-chain is in the SSB mode (as in some cases, that could / might be a GOOD idea.?) but there's also a good reason as to why a number of manufactures go through the cost (engineering & parts) to install an "APC" (automatic power control) trim-pot on their PCBs (even in "base-rigs".!) for use while operating in the SSB mode... :cautious:

    IMHO., the first reason for having an APC trim-pot, is that while operating a transceiver in a "mobile-situation", the input line-voltage can vary as much as 3 volts between engine-off & engine-on conditions.! :eek: And for my "comfort-level"., enjoy the idea that the voltage of my RF-chain stays stabile., and helps in keeping the devices within their limits (amps / watts).

    Secondly., by setting the APC "locked" collector / drain voltage trim-pot BEFORE setting the ALC (automatic level control) trim-pot, can not only improve the overall stability of the ALC limiting, but more importantly (to me that is.!) keep those little 2SC-1969s or IRF-520s from possible junction break-down or opening., especially during modulation peaks and / or high amounts of audio compression settings.!! :rolleyes:

    With "always-learning" Regards (y)
    Eric., aka: TEG :D
     
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  8. blasphemy000

    blasphemy000 Active Member

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    Yeah, I suppose in a radio that uses the regulator in conjunction with the ALC to control the out power on SSB, that makes sense. My Magnum Deltaforce does this. When you turn the power wide open on SSB though, it fully saturates the regulator, so it just puts out slightly less than what's going in, and doesn't actually do any regulating. I run it full power in SSB anyhow as it's only 32W-PEP. The Galaxy 88 Just dumps the regulator wide open in SSB mode and completely disables the high/low power switch. In SSB the driver/finals operate in linear mode and in that mode they're much less sensitive to supply voltage changes than in AM mode where they're driven beyond their linear mode to make the collector modulation work.
     
  9. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    And you'd be correct to a point - which is why the speculation. OR ... Why is there Speculation in the first place?

    2SA1012Specsummery.jpg
    The reason why this comes up...the Stats I see tells me there's something extra in it. As in, an extra sandwich of Positive and Negative - or Peanut Butter and Jelly - making a bigger mess....

    This article...

    https://www.electronics-tutorials.ws/transistor/darlington-transistor.html

    Helps to show what I'm trying to describe in how the input of the device, BASE - in relation to the other two - can be configured with another complimentary device - not just a simple "tacked on" PNP...and as to how the device can be biased internally - to affect gain - ANOTHER factor others have missed (150? Typical Gain figures of Merit of Darlingtons are 1000)

    And the issue of what I would call a larger value of such a PNP device usually indicates something is in place to provide a gain or extra stage. NTE's do this too - but not as large of a value in the specs.

    Nomad brought up a good point, or several - that raise even more questions. For in my own experiments I've used Darlington to replace the 2SA1012 above simply due to the critter behind the Mic simply had to have more than what the single part like the '1012 could provide.

    Nothing new here - just if people had researched more, the Darlington or whatever this device is a throwback from - they would have found cheaper and better sources.

    Palomar is simply a partaker of this process...

    So to me this is an interesting thread to see that someone has simply found a little "niche" in the marketplace in which to expound and reap benefits of providing the very device many of those critters are willing to devour.
     
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  10. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    I thumbed through this and let’s lay the technical stuff to the side and remember “volted” finals.

    You take that “battery voltage” and send it directly to those finals. There’s no BOOM!!! No smoke. No fire.

    ‘Nough said
     
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  11. Radioman56

    Radioman56 The Electronics Guy

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    Well.., maybe not in the short run sir...(y) But just just let that "volted-final" run a while., and especially accompanied with the typically "clipped" and / or "cranked-up" and / or "missing" AMC circuitry., and Ka-Boom., there go's your looong-gone ("rare-as-Hen's-teeth") 2SC-1969 final.!! :eek:

    BTW & FYI., if ever anyone needs one / any of them., I've got a small bag of 40+ original OEM Mitsubishi 2SC-1969s., which came from a friend of mine in Georgia., who acquired a LARGE bag of them (300+.?) from an retired (twice-over) / closed-out CB repair shop., of which, they even have the original "reverse-polarity-protection-diode" in them., as can be seen in the below article on my DCA-75 "component tester / identifier"...(y)

    Just "click-on" where it says "about 8 months ago" (under the name "Klein Communications") to see the full article & responses to it.

    May all be well with "The Force" my
    friends"..;)

     
    #101 Radioman56, Sep 4, 2019
    Last edited: Sep 4, 2019
    rabbiporkchop likes this.
  12. loosecannon

    loosecannon Sr. Member

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    Radioman56,

    I think i bought some of that guy's 1969's a while back. they were all pulls, but the all tested good.

    I must've fogrotten that the 1969 has that extra 'diode' inside them, because i don't remember seeing that, but i do know that the 2166 drivers have one in them.

    Oh, and i agree with the rest of you, Mark Charmin is a hack and a scammer.
    LC
     
  13. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    My point was, it was said that part would short and blow the finals because of an over volt. The radio isn’t making additional voltage, all it could send would be the supply which is exactly what you get from the volt mod. It doesn’t go boom instantly as we’re told will happen when anything other than a max mod is used.

    I won’t argue with you about length of time but I’ve never seen that happen with a “volted” radio. I’ll say it’s possible sooner or later but I haven’t ever experienced it.

    I have to say though, never seen any regulator short and blow a final, never. And the max mod isn’t the perfect part nor is it the lord and savior of the finals or anything else. Just as 13N10’s don’t magically explode and burn down your truck or house. But we’re told they do... now we’re being told a 754 or tip36 or whatever else will short closed and explode our radios. False.
     
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  14. blasphemy000

    blasphemy000 Active Member

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    It just seems like a normal PNP power transistor to me, nothing special to see here. A reverse biased Base-Emitter junction acts like a zener diode with a fairly precise breakdown voltage. Most transistors are rated between 3-5 volts, but there are some rated higher. It's just not normally a spec that gets much attention. EEVBlog did a video about this spec and it's use as a Zener clamp.

    The forward Base-Emitter voltage is a normal diode drop, I measured 0.56V @ 1mA from my diode tester. Just a standard single diode junction.
     
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  15. TM86

    TM86 Ooohhh, shiny!

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    Type slower you guys, I'm trying to take notes.
     
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