PC-999 Grant. how easy to make it do the Zero's?

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PC-999 Grant. how easy to make it do the Zero's?

Post by Mudslinger » 18 Sep 2013, 21:17

My Black fronted President Grant (PC-999AE) with Dual clarifier, is a great radio.

One of the only things that annoys me about it is that it will not do the Zero frequencies.

How easy is it to modify to make it do them?

I don't mind whether the coarse clarifier is modified to give more slide, or if a -5KC switch is fitted.


Many Thanks. 8)
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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by zephyr » 18 Sep 2013, 21:51

All you need to do is to change the two varactor diodes D40 and D44 (to the left of the two crystals) for ITT410's out of a side band Cybernet radio.

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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by slamjam » 18 Sep 2013, 22:41

Easier way is to remove a couple of jumpers and wire them to a switch which gives a 5kc jump, although it only works on ssb - I guess its not really needed on fm anyway.
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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by slamjam » 18 Sep 2013, 22:57

Image
Remove J36 and J37, link wires from the holes to a switch as per picture. Hey presto 5kc jump. I think from memory it goes +5 on USB and -5 on LSB hope that helps.
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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by cb4ever104 » 19 Sep 2013, 06:28

slamjam wrote:Remove J36 and J37, link wires from the holes to a switch as per picture. Hey presto 5kc jump. I think from memory it goes +5 on USB and -5 on LSB hope that helps.
Yeah , that's the way I do it . Originally posted by Claude , who got it from ....?

With this mod , plus the +10khz on the BRITE/DIM , plus the +/-2Khz slide on my course I can get to almost any frequency .
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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by Anthony123 » 19 Sep 2013, 07:03

Rather than having to flick extra switches to get the zeros and as some stations arnt actually on the zeros anyway, Some are under some are over so it would still require you to adjust the Coarse tune anyway.. It all seems to fiddly and time consuming... when all you need do is expand the tune range...

Either replace the The varactors for ones with more slide range... Higher lower PF range or replace the inductors that are part of the slide circuitry or even increase slightly the dc voltage to the circuitry.. or replace the fixed resistance to a lower value, These resistors are there to centre the tune control to give it the same swing either side, but you can alter them slightly to give a bit more range, dont remove them altgether though or just jump them out as the circuit needs some resistance ,

. .. One or all of these mods will increase the slide range.... Over the years ive added coarse tune to cobra 146's and such radios... its reasonably easy to get a slide range of plus/minus 6 khz from centre... It does however take a bit of trial and error..

Generally thought you will get slightly more swing range on LSB than USB..

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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by bigpimp347 » 19 Sep 2013, 07:20

'sits back and awaits nicks presence' :)

i was told you need to change the inductors for those out of a cobra/superstar boarded radio to get more swing on the Coarse control..

if i knew of this simple switch mod i would have done loads by now..!!
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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by Mudslinger » 19 Sep 2013, 07:24

Thanks for the help everyone.

I think the Clarifier having more slide appeals to me most.

I don't like having buttons on the front not doing as they are meant to, unless really necessary.

I think I will wait until I have some other stuff to go to Nick, and send it then.
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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by cb4ever104 » 19 Sep 2013, 09:58

bigpimp347 wrote:'sits back and awaits nicks presence' :)
Yeah , so am I :) The GRANT is nothing like a 146/148 GTL . The loop oscilator section is much more stable and if I remember right nearly all that section has to be ripped out and replaced if you want +/-5khz slide .

The GRANT is a great radio as it is . With the +10 and +5 switch mods it makes it even better without sacrificing the stability of the radio .

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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by Mudslinger » 19 Sep 2013, 10:47

The reason I want to do it, is that I prefer the way the Grant works compared to my Jackson. The only thing is that the Jackson has a much bigger clarifier slide and a +10KC switch.

If the Grant did those then it would be near perfect.

The Extra bands that the Jackson has compared to the Grant are nearly always completely empty except for morse code on the top of super high.
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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by Anthony123 » 19 Sep 2013, 12:53

Why does it need to be ripped apart.... Its not a difficult mod... the coarse tune is doing basically what you want it to do anyway... other than the extra range... Its not difficult... True the grant isnt like a 146 but if you can get 12 khz shift in total from a 146 that didnt have a coarse tune to start of with then it should be simple to mod a radio that has on already on it.... Its not rocket science its basic electronics... Most of the clarifier only radios can be made to have a coarse tune and a decent one at that. have a look at the grants schematic diagram and work out what needs to be changed... Its not difficult.

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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by Black Spirit » 19 Sep 2013, 13:26

Anthony123 wrote:Why does it need to be ripped apart....
Ripped apart was a bit extreme, I explained some time ago why the Grant after clarifier is opened up and Grant classic [which has both Coarse and fine] didn't have much coarse slide, It is just down to inductor value and .25 crystal difference.

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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by Mudslinger » 19 Sep 2013, 14:34

So Nick, is it a fairly easy job to do?
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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by Black Spirit » 19 Sep 2013, 15:00

Mudslinger wrote:So Nick, is it a fairly easy job to do?
I would go for the "slamjam" project :D I have never tried it myself but as long as you can get to the zeros on USB then thats all that counts.

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Re: PC-999 Grant. how easy to make it do the Zero's?

Post by Mudslinger » 19 Sep 2013, 15:08

It does look quite straightforward.

The only thing that bugs me is that is says it goes +5Kc on USB and -5Kc on LSB.

I think it would be easier if it just went -5Kc on both.
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