SS390 conversion to 10 metres

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johnkyrle
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SS390 conversion to 10 metres

Postby johnkyrle » 20 Sep 2017, 07:16

I have a SS3900 circa mid nineties and would like to convert it to operate on 10 metres.However,I would like to keep the CEPT (band c) and the rest of the high bands as is and convert the useless a and b band to operate on 10 metres.Is this a possibility?At the moment it will reach up to 28.305 on band f but totally useless as that spectrum of the band is only for date/c.w operation.
Anyone got any ideas? :wave:

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ROTEL240
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Re: SS390 conversion to 10 metres

Postby ROTEL240 » 20 Sep 2017, 09:07

Send black spirit a pm if it can be done he is your man.

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MrWeetabix
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Re: SS390 conversion to 10 metres

Postby MrWeetabix » 20 Sep 2017, 09:46

you might struggle with that..... logically, I;d imagine you'd have to have mids and Hi on A and B then the rest to go up-over from there..... but I'm not a rig doc.

Black Spirit will know the answer :-)
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Snake Plissken
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Re: SS390 conversion to 10 metres

Postby Snake Plissken » 20 Sep 2017, 10:43

Hi John,

This can be done by fooling the binary adder IC's with the required N-code (usually achieved with a network of signal diodes)...

I have an old 148 GTL-DX Mk2 that does it this way; it uses an ancient JD Custom Multimode band converter EPROM...The EPROM is really just giving the UK 27/81 band with the correct frequency offset and no alpha channel gaps, the other bands are achieved by using the diode network method...

This radio covers LoLoLo/LoLo/Lo/Mid/Hi/HiHi/UK40, and then from 28Mhz up to around 29.6Mhz IIRC...some modification of the VCO circuit is required to achieve this, I've never experimented with the 3900's upper end capabilities so yours may go further...

If the lowest frequency band you want to keep is the CEPT one, I would guess you shouldn't have a problem getting up to 30Mhz....

As mentioned above, have a word with Nick Black Spirit! By reputation he will be the best source of advice on your options.... :thumbup:

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ch25
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Re: SS390 conversion to 10 metres

Postby ch25 » 20 Sep 2017, 15:31

EPT3600 mod:
Connect together pin 13 and 15 of IC7 with a switch.
Radio will go up to 29.590
Done.

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johnkyrle
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Re: SS390 conversion to 10 metres

Postby johnkyrle » 20 Sep 2017, 19:18

Thanks for all that guys.I was thinking of asking Nick as he did the re-alignment on this radio for me.ch25 is it really that easy?If so,how does the band selector operate after that mod?

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gmham
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Re: SS390 conversion to 10 metres

Postby gmham » 20 Sep 2017, 19:50

No rig doctor but would well imagine it's going to be deaf at either end ie you won't be able to have the best off both worlds. Personally would keep it standard and buy yourself one off the modern 26to 30mhz rigs.
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Re: SS390 conversion to 10 metres

Postby slamjam » 20 Sep 2017, 20:19

It can be done. My old 3900 was modded to go to 28.560 with a flick of a switch. It worked on band F only otherwise it was standard. The RX needed bringing up as was a bit deaf on the top end. The other way would be to swap the mixing crystal and lose ssl to gain ssh band. Which would take it to 28.755 much more useful than 25.615 ssl band.
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gmham
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Re: SS390 conversion to 10 metres

Postby gmham » 20 Sep 2017, 21:13

Yep not saying it cant be done all I am saying in my view its dont expect great rx performance at 29mhz + as well as on low 27mhz, its got to be set for peak either end not both.
had a cobra 148gtldx done as the chap above advised : quote " This can be done by fooling the binary adder IC's with the required N-code (usually achieved with a network of signal diodes)...
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ch25
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Re: SS390 conversion to 10 metres

Postby ch25 » 21 Sep 2017, 06:05

johnkyrle wrote:Thanks for all that guys.I was thinking of asking Nick as he did the re-alignment on this radio for me.ch25 is it really that easy?If so,how does the band selector operate after that mod?

It works as before, but last band ch40 will be 29.590MHz

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johnkyrle
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Re: SS390 conversion to 10 metres

Postby johnkyrle » 21 Sep 2017, 19:28

gmham wrote:Yep not saying it cant be done all I am saying in my view its dont expect great rx performance at 29mhz + as well as on low 27mhz, its got to be set for peak either end not both.
had a cobra 148gtldx done as the chap above advised : quote " This can be done by fooling the binary adder IC's with the required N-code (usually achieved with a network of signal diodes)...

Not worried about the ssl's as no one is on there and it is a military frequency allocated 1st priority segment so pretty much a no go!!
Rather have it set up for the mids/highs and loose the useless lower part of the band

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speeddemon
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Re: SS390 conversion to 10 metres

Postby speeddemon » 21 Sep 2017, 22:23

:ugeek:
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Re: SS390 conversion to 10 metres

Postby speeddemon » 22 Sep 2017, 00:07

:ugeek: :D :lol:
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