Spectra 900 mhz mods

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Spectra 900 mhz mods

Postby KC9MEC » Thu Nov 20, 2008 10:43 pm

Hi,
I just went to mod two 900 spectra's I received one went as normal ,but the other has a different board can't tell where to do the mod, have you ever ran into this?
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Re: Spectra 900 mhz mods

Postby Cowboy » Sat Nov 22, 2008 9:45 pm

KC9MEC wrote:Hi,
I just went to mod two 900 spectra's I received one went as normal ,but the other has a different board can't tell where to do the mod, have you ever ran into this?

Pics of what/where you're trying to mod would be helpful...

Can't locate the VCO? Uh oh...
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Re: Spectra 900 mhz mods

Postby wa6jbd » Fri Dec 05, 2008 12:10 am

Yes, I have. I purchased a lot of 20 or so 900 Spectras on eBay a while ago, and a couple of them were a bit odd. Not only were the VCO boards completely different, the MLM boards have a different connector than anything I've seen. I have yet to attempt to tackle retuning the VCO on these. I may just end up using them as-is. They're very early models, evidenced by their version 1.something firmware.
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Re: Spectra 900 mhz mods

Postby n5api » Sun Jan 11, 2009 8:18 pm

I haven't had a lot of luck with modding those older VCOs. I ended up throwing the two I had (and the radios they were in) into my parts bin after harvesting the 30 watt PAs. The fact that some of the caps had puked and probably goofed up a few of the boards helped seal their fate. That might have been why the mod didn't go too well. I replaced the caps, but I don't have the tools to see just how much damage they did.

73,
John, N5API
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Re: Spectra 900 mhz mods

Postby kk6rq » Thu Apr 30, 2009 2:57 am

I have a bunch of filthy, dirty, ex-taxi 900 Spectras and at least half of them are the old 1.x firmware.
(I believe they come from the 19th century); Anyway, if I recall correctly, you run the 220k resistor
from the right side of the big, flat white SMD cap to a ground hole. It should be obvious; it doesn't exist on
the newer VCOs and its in the same general area where you would put the resistor on the newer ones.

Sorry I have no manual for these older models so I can't tell you the component number.

The 1.x'ers are ugly and feature-poor but as long as you replace those electrolytic caps (and they haven't
yet destroyed the board in their vicinity), they work just as well as a newer Spectra. Of course most of my control
heads were useless and worn out by the time I got them. Cabbies spilling 7-11 coffee on them,
presumably......

Bob
Last edited by kk6rq on Tue Jun 23, 2009 11:13 pm, edited 1 time in total.
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Re: Spectra 900 mhz mods

Postby kj6ko » Fri May 22, 2009 4:29 pm

You have older VCO's They can be identified by the large thing that looks like a "chip cap" on the two VCO lines. Just put a 100K resistor in the same place you would normally put the 220K resistor and it should lock up fine. These are usually acompanied by the older MLM boards with the funky "blade" connectors.
FYI,
If they are KMA radios, they will be good for a min of 32ch conventional. If they are KGA radios,, probably only 1 or 0 conv channels. BUT... you can force load a codeplug from a KMA radio into it and it will work fine! The trick is finding a codeplug with the same FW to clone from. I have a lot of 1.00 codeplugs for KMA radios! I just tried this with a ver 2.13 KGA radio. Was only ONE conv channel with NO SCAN or DIR functions. I had a V2.13 KMA codeplug with 128ch conv and forceloaded it into the radio and it converted the radio to a KMA radio with SCAN and DIR!
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Re: Spectra 900 mhz mods

Postby Astro Spectra » Sun Jul 19, 2009 3:49 pm

Is it possible by suitable moflag gardening to enable high/low power switching? The units involved are old 1.00 and maybe 1.2 firmware units.
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Re: Spectra 900 mhz mods

Postby kk6rq » Tue Jul 21, 2009 1:45 pm

Astro Spectra wrote:Is it possible by suitable moflag gardening to enable high/low power switching? The units involved are old 1.00 and maybe 1.2 firmware units.


Not really; since there's no 'Low Power' function on any regular Spectra, the only way we ever could do that was
by making duplicate Zones with the first set to High and the second set to Low. Zones require v.6.x firmware
so you're basically SOL. Duplicate modes is your only choice.
If you're asking whether there's a moflag that enables high/low power STRAPPING, then yes. But no operator
selectable switch of any sort.
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