DigiMax Lite

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radio pete
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DigiMax Lite

Post by radio pete » 31 Jul 2018, 18:01

Hi has any one used the DigiMax Lite conversion kits fro Australia the say no band switch & a 3 digit display 512 cannels ?

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Re: DigiMax Lite

Post by MrWeetabix » 01 Aug 2018, 07:35

We have a couple of active members from Australia on the boards, hopefully one of them may be able to assist.
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Re: DigiMax Lite

Post by radio pete » 02 Aug 2018, 09:46

thankyou Me weetabix

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Re: DigiMax Lite

Post by lbcomms » 02 Aug 2018, 20:38

They are from a place about 30 minutes drive from here, a few of the locals have had them installed in older radios such as the first gen Cybernet SSB to expand the channel capability.

We've never used them ourselves (we make our own version that has similar functionality but uses a completely different technology) but the people that have bought them are happy with them. Not heard a bad thing about the digimax or the guy selling them.

Not hugely popular down here, 99%+ of CB use locally is on 35 (27.355) LSB, so most people don't bother expanding radios any more.

Both his and our versions require expert installation and proper test gear, as well as knowledge on things like broardbanding techniques for the RF and VCO stages to get the most out of them. They are not "plug and play".

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Re: DigiMax Lite

Post by radio pete » 03 Aug 2018, 11:44

Thank you for your reply Ib comms do you have any info to hand on you exp kit? please send via PM if you wish, installing is not a problem for me.

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Re: DigiMax Lite

Post by astradyne » 03 Aug 2018, 13:59

I fitted a DigiMax Lite into a 148 GTL-DX. It was a very simple job to do. I bought the kit version and built the PCB myself (works out cheaper) and fitted the board into the radio with no issues at all. The band selector is no longer used after the mod as the conversion provides a constant tuning. There's also a scan function on board which is linked through the squelch.

The ribbon cable from the main PCB to the channel selector needs screening as there's a slight squeal which is audible on low volume levels. It doesn't effect the TX side of things though. The radio really didn't need much tuning at all.

I'll pop some pics up when I get a little spare time later.
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Re: DigiMax Lite

Post by lbcomms » 03 Aug 2018, 16:51

Pete: The development / prototype of it a couple of years ago was shown in this thread: viewtopic.php?f=53&t=49419. The final version was much the same but had a proper SMT circuit board instead of the perfboard used in the prototype.

We sold about 20 or 30 of these, but the supply of one of the critical components (the replacement PLL) dried up. It's a spare time long term project to redesign the board to take a modern fractional-N type PLL chip, but it's been dragging for a few months due to lack of time to play.

The difference between our version and the digimax is that the digimax retains the original radios PLL IC, whereas ours replaces it. There are pros and cons to both methods, replacing the PLL with a more modern one lets it work in smaller spacings (100Hz as opposed to 10KHz) and control the mode offsets / clarification from the PLL. This means a very steady reference can be used (under 1ppm change from -10 to +50 degrees C) so no drifting.

It also means it will work with "non expandable" PLL chips like the uPD2824 and the LC7131.

The downside is you can run into RF issues when installing it. A spectrum analyzer is preferred to make sure the radio is clean, especially if it's for a paying customer. So the Digimax is a better DIY proposition if you haven't got all the gear a radio service shop would have.

Astradyne: That's a pretty broad radio to put it in, little to no broadbanding needed there. A 40 channel radio such as the first gen PLL02A or the FCC version of the Uniden 858 will be a lot more work to get full coverage out of it.

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Re: DigiMax Lite

Post by dt307 » 04 Aug 2018, 02:16

yes have fitted a few and there is some new stuff comming, quote "Just finished a pll transplant PCB for 8719 radios to get 511 ncodes and 5kc on digimax lite control....

Next board is a pll transplant to uPD2824 chassis for.same 511 & 5kc pll upgrade which will need more work... 10.24 OSC etc... Working to get that done " (from one of the guys working with him on new stuff).

what i know about the digimax lite.....universal controller (pic) with a led driver for the 3 digits.
some slick programming ie you install the digimax a bit like a prom (cut all the programing lines remove the selector solder the ribbon to the pll lines and a plug and play encoder)
on start up you enter programming mode and then select your ncode for ch1 and select the pll 8719/858/145106 ect then it will calculate/run the installed program for your input.
channel 1-40 is mid band and shows 3a 5a ect for alphas
41 + is semi frequency display ie ch 55 is 27.555 chanel 78 is 27.785 ect ,channels below channel 1 count in minus channels .
depending on pll sets the max channels ie 256 channels are not possible with a mb8719 pll as 128 is the max as its a 7 bit pll .
if you need any more info give me a shout
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Re: DigiMax Lite

Post by dt307 » 04 Aug 2018, 02:22

astradyne wrote:
03 Aug 2018, 13:59
I fitted a DigiMax Lite into a 148 GTL-DX. It was a very simple job to do. I bought the kit version and built the PCB myself (works out cheaper) and fitted the board into the radio with no issues at all. The band selector is no longer used after the mod as the conversion provides a constant tuning. There's also a scan function on board which is linked through the squelch.

The ribbon cable from the main PCB to the channel selector needs screening as there's a slight squeal which is audible on low volume levels. It doesn't effect the TX side of things though. The radio really didn't need much tuning at all.

I'll pop some pics up when I get a little spare time later.
i use this circuit i ran across from gerhard maurer to stop multiplexing noise on his counters it stops all the noise from a digimax as well
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Re: DigiMax Lite

Post by astradyne » 04 Aug 2018, 08:21

dt307 wrote:
04 Aug 2018, 02:22
astradyne wrote:
03 Aug 2018, 13:59
I fitted a DigiMax Lite into a 148 GTL-DX. It was a very simple job to do. I bought the kit version and built the PCB myself (works out cheaper) and fitted the board into the radio with no issues at all. The band selector is no longer used after the mod as the conversion provides a constant tuning. There's also a scan function on board which is linked through the squelch.

The ribbon cable from the main PCB to the channel selector needs screening as there's a slight squeal which is audible on low volume levels. It doesn't effect the TX side of things though. The radio really didn't need much tuning at all.

I'll pop some pics up when I get a little spare time later.
i use this circuit i ran across from gerhard maurer to stop multiplexing noise on his counters it stops all the noise from a digimax as well filter.jpg
That's great. Thanks.
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Re: DigiMax Lite

Post by radio pete » 04 Aug 2018, 09:08

Many Thanks Guys for your replies I will order the kit and start to play looks to be easy as pie

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