is it really worth the upgrade from the mrf477? since the 455 are not made anymore what's the sustitute for that? advantage / diadvantages ? thanks in advance 73
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2510 pwr mods
- Thread starter rfoverlord
- Start date
477 to 455
I think I understand your Question..
Actually, the MRF477 and MRF497 were discontinued around the same time. I heard (not confirmed) that Motorola revisited production for a short time, and I am not sure if they are still being made at all.
The Mod to use the MRF455 originally was incorrect (later investigated and corrected - around the time President France converted to the New Mrf 455 Lincoln) The original mod thought you could actually get full potential from the MRF455, It is possible but not without some other circuit mods.
The thing that made it a popular alternative, was that with simple swapout you could bring back to life a radio with a dead MRF477 or MRF497, and get 'Nominal' output. The MRF455 was the ONLY final available with the proper characteristics to be used in place of a HR series Final. And 'Once apon a time' you could get MRF455's for about $12 a piece, when the dwindling supply of 497's and 477's were $35 ea.
So, all in all the swapout is best for when there is no other alternative, But the circuit can be modified to get better than 'Nominal' output.
Roger
I think I understand your Question..
Actually, the MRF477 and MRF497 were discontinued around the same time. I heard (not confirmed) that Motorola revisited production for a short time, and I am not sure if they are still being made at all.
The Mod to use the MRF455 originally was incorrect (later investigated and corrected - around the time President France converted to the New Mrf 455 Lincoln) The original mod thought you could actually get full potential from the MRF455, It is possible but not without some other circuit mods.
The thing that made it a popular alternative, was that with simple swapout you could bring back to life a radio with a dead MRF477 or MRF497, and get 'Nominal' output. The MRF455 was the ONLY final available with the proper characteristics to be used in place of a HR series Final. And 'Once apon a time' you could get MRF455's for about $12 a piece, when the dwindling supply of 497's and 477's were $35 ea.
So, all in all the swapout is best for when there is no other alternative, But the circuit can be modified to get better than 'Nominal' output.
Roger
but is it really a worth while "upgrade" or would it be better just to run a small amp 100 - 150 rms instead? my final is fine and i do have a spare 497 is it really worth it to put in a 2sd1446 or a mrf455? i don't want to have to run another device in my already rf crowded mobile but i could use a boost in output for the 2510. rogerbird what's your opinion since it was you that made this one of my favorite rigs to use. tnx 73
Worth it or not
The point I was trying to make in the previous reply is.
that the swap out typically does not offer more power.
By nominal power I mean 25W SSB/10W AM, Maybe a lil more.
You would probably be better off with 'external' devices for more power. The 497 or the 477 can yeild as much as 50 W, I hae not seen that with the 455, I only have heard of a way to get that much out of a 455, so far I have yet to see that.
Note: I am talking about AM Dead Key, unmodulated, and SSB PEP.
I have not tried a SD1446, and do not know the Specs of it.
Roger
The point I was trying to make in the previous reply is.
that the swap out typically does not offer more power.
By nominal power I mean 25W SSB/10W AM, Maybe a lil more.
You would probably be better off with 'external' devices for more power. The 497 or the 477 can yeild as much as 50 W, I hae not seen that with the 455, I only have heard of a way to get that much out of a 455, so far I have yet to see that.
Note: I am talking about AM Dead Key, unmodulated, and SSB PEP.
I have not tried a SD1446, and do not know the Specs of it.
Roger
our 455 final lincolns and jacksons will key 70w on fm the 477 final will key 50w providing the limiting resistors in the power controll circuit have been put back to what they were before the manufacturer limited the radios to around 30/35w to stop people frying the radios, the downside i dont like from the 455's is you have to turn the ssb alc so far back so that your peak power is not too high for a regular cb linear that your average talkpower is lower than what it would be with the 477 final radio, if all you need is 10 or 12 watts on a whistle to drive your amp then i would stay with the 477's, if you need nearer 20w or more then i would prefere the 455 version.
okay, i guess i should be more specific. i wanted more output on ssb (don't care about am) without the hassle of an amp. i guess it's back to run an amp, was only trying to get around 100w pep. thanks for taking the time to respond 73
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