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Hyperno_1979
Intermediate Member
Username: Hyperno_1979
Post Number: 394
Registered: 12-2005
| | Posted on Saturday, August 04, 2007 - 7:36 am: | 
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OK i have an 18 channel TRC-448 that i have had since 1978. Yes 18 channel, that is what our guv'ment decided we could have instead of the switch to 40 from 23. Now it has 5 switches on the back. The middle one lets me get up to around channel 35 etc. What the other 4 do i still don't know to this day. What i am asking is can i remove the other 4 switches just so i can cover the higher part of the 40? Actually when the middle switch is activated i can only tx and rx in ssb NOT am. Any help or ideas greatly appreciated.
CEFFFCEF
Bob
CEF703/CVC26
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Tech237
Moderator
Username: Tech237
Post Number: 863
Registered: 4-2004
| | Posted on Saturday, August 04, 2007 - 8:38 am: |
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Bob,
You probably can (give me a chance to find the info on this radio that I have). When you remove a switch you will probably need to jumper a track near the PLL chip as the switches generally either open a track or place +5V or ground on it.
Simon
Tech237
N7AUS
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Hyperno_1979
Intermediate Member
Username: Hyperno_1979
Post Number: 395
Registered: 12-2005
| | Posted on Saturday, August 04, 2007 - 9:21 am: |
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Simon,
Just had a thought, would it be easier for me to obtain a 40 channel block and install that instead of leaving 1 switch that way i will get all 40 rather than most? I thought about wopping one out of an old Super Tomcat i have, even one of my old Animal Mode sets. I have and can find very little on Realistic radios so anything you have will be a plus.
Cheers Mate.
CEFFFCEF
Bob
CEF703/CVC26
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Penrider
Intermediate Member
Username: Penrider
Post Number: 194
Registered: 1-2007
| | Posted on Monday, August 06, 2007 - 12:22 am: |
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have no idea what chip your 18channel uses, the US 40channel model uses either the upd858 or the sm5104 chip. the only thing I could find on the radio was in sam's and it was regarding expo kits. basically it mentioned an oddball set of mixing chrystals (same as the Wards GEN719A). So, you MAY be able to use either of those two chips if the rest of the radio is the same as the 40ch. Let me know, and I'll send you the link I found the info at. Finding it was a pain.
Sean
CEF867
Two tin cans and a string, it's still a contact...BTW, I need my can back when we're done!
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Hyperno_1979
Intermediate Member
Username: Hyperno_1979
Post Number: 398
Registered: 12-2005
| | Posted on Monday, August 06, 2007 - 7:14 pm: |
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Thanks Seano,
That's something i never even thought about. The chip. I could be wrong but i think all our 18 channel jobs were the same as the 40's except for the block. This was in the day when we switched from 23 channels. Instead of going to 40 like the rest of the world our Guv'ment decided that 27 mhz would be phased out by 1982 and UHF would then be our CB allocation. Yeah that worked. So they passed a law that all 27 mhz radios would be only 18 channel. Next thing we knew 40 channel versions of the same radios were available, so stores were flooded with customers buying the 40 blocks. Most were done this way but some, like mine, were just left modified. By doing that i miss out on some of the 40 channels. The old girl still works great and i want to have it in good order for my collection. I know it's hard to find a great deal of info on Realistics, I've tried also. I'll whip the covers off and check the chip in her and get back to you.
Thanks Again Champion,
Bob.
CEFFFCEF
Bob
CEF703/CVC26
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Penrider
Intermediate Member
Username: Penrider
Post Number: 196
Registered: 1-2007
| | Posted on Tuesday, August 07, 2007 - 12:53 am: |
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NP, let me know how it turns out.
Simon also probably knows more about that type of thing than I do, I just wanted to check it out to see if I could figure it out myself.
Sean
CEF867
Two tin cans and a string, it's still a contact...BTW, I need my can back when we're done!
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Hyperno_1979
Intermediate Member
Username: Hyperno_1979
Post Number: 431
Registered: 12-2005
| | Posted on Saturday, September 15, 2007 - 1:51 am: |
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Matty...KV,
Mate i have sent you a couple of e-mails and they come back blocked. Has this something to do with me? If you wish you can e-mail me to confirm. Or post here.
CEFFFCEF
Bob
CEF703/CVC26
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Hyperno_1979
Intermediate Member
Username: Hyperno_1979
Post Number: 438
Registered: 12-2005
| | Posted on Friday, September 21, 2007 - 11:32 am: |
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I need help here. I have been given a TRC 521 and have been told that i can wop the 40 channel block out of it for my 448. Can this be done? I know they have a different chip but would the block go into the mighty 448? Any help much appreciated.
CEFFFCEF
Bob
CEF703/CVC26
I Don't Have a Life Ban From Canada...lol.
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Penrider
Intermediate Member
Username: Penrider
Post Number: 213
Registered: 1-2007
| | Posted on Sunday, September 23, 2007 - 2:04 am: |
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see if you can find out what PLL the 521 uses. if it's the same as the 40channel version of the 448, it'll work. If it's not exactly the same, you'll have to determine the pin layout on Both PLL's and see if they at least line up in order.
If they don't match up, I wouldn't do it. The board expects to see "x" freq. at "x" pinout. Then the mixing chrystal(s) take over and produce "27.115, etc." I don't think it would hurt the radio if they don't match. I think you would just have a really oddball set of channels. If it does match, see if the mixing chrystal(s) in the 40ch 448 and the 521 match. That IS necessary in order to use the 521 parts. if not, you'll have to find the chrystals from the US 40ch. 448. and if you found those, you would probably find that PLL also. which is Still your Best Bet.
Sean
CEF867
Two tin cans and a string, it's still a contact...BTW, I need my can back when we're done!
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