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Thread: Astro Spectra UHF Band frequency range

  1. #1
    RussianE39 No Longer Registered

    Default Astro Spectra UHF Band frequency range

    Hi guys!
    I'm trying to find sweet-spot bandsplit radio for myself and seems best one is R-band, but it is 438-482. Is there any possibilities, that it work reliable up to 433 Mhz range ? Here in Moscow hams sitting on 433-434Mhz, so I need to TX there, but I also want to listen stuff on 450-460 (local police frequencies).


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    Извините за мой русский школу ... Радио VCO может быть настроена вниз, используя немного краски серебра. Вы знаете, этот метод?

    http://batboard.batlabs.com/viewtopi...t=silver+paint

    In english: The radio VCO can be tuned down, using some silver paint. Do you know of this method...


    Существует также метод резистора:

    http://www.repeater-builder.com/motorola/spectra/spectra-900mhz-vco-mod.html

    There is also the resistor method...

    Last edited by Astro Spectra; Feb 12, 2013 at 08:51 AM.
    It is a fine thing to be honest, but it is also very important to be right

  3. #3
    Will No Longer Registered

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    "In English: The radio VCO can be tuned down, using some silver paint. Do you know of this method..."

    Stay well clear of this type of mod on the VCO. I have had to repair way to many. Not all are recoverable.

    The 403 - 433 will go up a few fairly easily to 438.

    The 450 to 480 was the normal range most seen here in the US. They do not go much below 440, and that is with help.

    Astro "
    R-band, but it is 438-482." this IS a missprint. Should read 450 - 480., Spectra is the same range, 450 - 480.

    There was a 453 to 488 range but has the same model numbers as the 450 480 radios.


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    @Will, I think he is talking about the motorcycle split which starts at 438 MHz. I have done both the paint job (for both Spectra and Quantar as well as the resistor mods (900 MHz) on many radios without long terms issues. And I align everything according to the book.
    It is a fine thing to be honest, but it is also very important to be right

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    Quote Originally Posted by Astro Spectra View Post
    @Will, I think he is talking about the motorcycle split which starts at 438 MHz. I have done both the paint job (for both Spectra and Quantar as well as the resistor mods (900 MHz) on many radios without long terms issues. And I align everything according to the book.
    Please post some detailed information on your Quantar modifications in the Infrastructure forum if you would. I'd enjoy reading that.

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    Quote Originally Posted by Will View Post
    "In English: The radio VCO can be tuned down, using some silver paint. Do you know of this method..."

    Stay well clear of this type of mod on the VCO. I have had to repair way to many. Not all are recoverable.

    The 403 - 433 will go up a few fairly easily to 438.

    The 450 to 480 was the normal range most seen here in the US. They do not go much below 440, and that is with help.

    Astro "
    R-band, but it is 438-482." this IS a missprint. Should read 450 - 480., Spectra is the same range, 450 - 480.

    There was a 453 to 488 range but has the same model numbers as the 450 480 radios.

    I have some factory 438-470 W3 low-mid power units sitting here on the shelf. Super rare, but the 438-470 split is out there.

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    Motorcycle Spectra 438-470 MHz brochure:

    http://www.repeater-builder.com/moto...-specsheet.pdf

    @d119 good idea I have some photo's here somewhere.

    I know that silver paint is probably not the ultimate solution but for ones I did back in 2004, documented briefly here:

    http://batboard.batlabs.com/viewtopic.php?f=10&t=35537

    it has lasted longer than the caps. Oh, and we're talking silver paint with real silver in it not just silver colored paint. You can tell as even a small pot is noticeable heavy. The best stuff is used for thick film electronic hybrid screen printing. I think it was like 100 bucks a pot back in '03/04.
    It is a fine thing to be honest, but it is also very important to be right

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    I have done many of these types of conversions. Here is a thread relating to it (post #16 on):

    https://www.p25.ca/threads/1198-XTS3...nd-programming

    That thread references two other threads related to this:

    https://www.p25.ca/threads/447-Astro...umper-settings

    And:

    https://www.p25.ca/threads/461-XTS2500-Fail-001-Error

    The way I have described is more permanent than using conductive ink but the overall effect is the same; pulling the VCO down in frequency...

  9. #9
    RussianE39 No Longer Registered

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    Damn, seems astro spectra I bought on ebay is 450-480Mhz. So, what should I do/buy to convert it to 438-470 Mhz one ? Or even better 433-465 :-) I've got a buddy with HP RF Analyzer and good skills of SMD soldering.

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    Quote Originally Posted by RussianE39 View Post
    Damn, seems astro spectra I bought on ebay is 450-480Mhz. So, what should I do/buy to convert it to 438-470 Mhz one ? Or even better 433-465 :-) I've got a buddy with HP RF Analyzer and good skills of SMD soldering.
    There are a couple of threads covering this. I hate to say it but please seach the site, look for things like VCO, spectra and astro spectra.

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    Those threads I called out are very specific and have instructions on how to modify the VCO, one I did went from 450-482 to 420-465 or so for a friend to use in Germany. You can get the desired range 433-465 no problem but it will take some soldering skills as I described. Seriously, read them if you haven't yet it is exactly what you want/need. I have performed this mod dozens of times with no problems whatsoever. Keep in mind you'll need a R2 Motorcycle/Canadian/European codeplug to make the radio play properly below 450 MHz.

  12. #12
    RussianE39 No Longer Registered

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    Quote Originally Posted by Alpha View Post
    Those threads I called out are very specific and have instructions on how to modify the VCO, one I did went from 450-482 to 420-465 or so for a friend to use in Germany. You can get the desired range 433-465 no problem but it will take some soldering skills as I described. Seriously, read them if you haven't yet it is exactly what you want/need. I have performed this mod dozens of times with no problems whatsoever. Keep in mind you'll need a R2 Motorcycle/Canadian/European codeplug to make the radio play properly below 450 MHz.
    Yeah, the most specific one is this: https://www.p25.ca/threads/447-Astro...=2858#post2858
    But are this the only modifications needed ? I mean only VCO should be modified ? No need to touch various RF filters ? Usually Motorola puts very nice filter stages to cut everything, except working band split for their radios.

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    The filters will streach nicly the losses are negligable.

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    Yes, that plus the proper codeplug is really all that's necessary. If you can find a Euro/Motorcycle/Canadian front end that's 438-470 it's a tiny bit better at the low end than the standard R2 (450-482) front end, but they have no problem going 10-15 MHz out of band without getting too deaf. The PA's are nice and wide band, they will take a bit more current to put out full power out of band but again they have no problem going 10 even 20 MHz out of band. The other stuff like the IF and audio circuitry is all just fine as-is.

    Quote Originally Posted by RussianE39 View Post
    Yeah, the most specific one is this: https://www.p25.ca/threads/447-Astro...=2858#post2858
    But are this the only modifications needed ? I mean only VCO should be modified ? No need to touch various RF filters ? Usually Motorola puts very nice filter stages to cut everything, except working band split for their radios.

  15. #15
    RussianE39 No Longer Registered

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    Thanks for your help, guys. So, best way would be to find HRE6012B, right ? Or at least HRE6002 ?