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Message |
    
Narf_edwards
Junior Member
Username: Narf_edwards
Post Number: 26
Registered: 3-2005
| | Posted on Friday, December 02, 2005 - 12:47 pm: | 
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I picked up a used Palomar 225 with the 2SC2290 transistors in it.I can only get it to deliver about 90-100 watts with 10-15 watts in ssb.Nothing appears burnt or gets warm...in fact the amp is mint inside.Would anyone know the reason for the low output.Is it possible it would work at all with 1 final blown?
Thanx
Narf |
Vanillagorilla
Intermediate Member
Username: Vanillagorilla
Post Number: 352
Registered: 4-2005
| | Posted on Friday, December 02, 2005 - 2:52 pm: |
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That SC2290 is rated 80w @ 4W input...looking at that... "YES" it looks as though one Transistor is shot.
Had the same thing happen to mine although mine was an older version with 2 MRF455's (60w @ 3w input) After a little DX I found I was only doing around 50-80w.
With no way to test them I bought a matched set of SRF3775's (70w @ 4w input)and replaced them. Now where I used to see a max of 180w with my Grant I see 230w driving it with 2.5w swinging to 16. Stays luke warm.
All was well again in Loserville 
Hank '905
CEF 559 |
Narf_edwards
Junior Member
Username: Narf_edwards
Post Number: 27
Registered: 3-2005
| | Posted on Friday, December 02, 2005 - 4:25 pm: |
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Thanx Van,I did manage 120 watts with 35-40 watts swing...it looks so clean inside tho...like brand new.No excess heat or burnt components..I understand 2SC2290 were not originally used in these amps.Serial dates it as '93..it has the arched top on the blue heatsink.I wish I could test the pills without ripping them out.
....I'll wait and see if anyone else has any ideas
Thanx for the info
Narf |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1992
Registered: 7-2004
| | Posted on Friday, December 02, 2005 - 4:26 pm: |
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what TYPE of meter you usin' to measure watts? what watts the radio alone swinging? if the radio is ONLY swinging to 5 or 6, could be the meter only reading the RMS swing or the radio way down low.(my AR3500 will show 160 or so on peak side of diamond sx100, but under 100 on avg side-& that's the same 2 x 2290) |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1999
Registered: 7-2004
| | Posted on Friday, December 02, 2005 - 7:18 pm: |
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we posted at the same time, narf....you answered my questions pretty much, with the 40 watts swing-assuming you're measuring that with the same wattmeter, & not just going by 'what you know it will do'. WAY too much, probably 1 transistor has seen better days. 20 watts PEP is better for the 2 2290's. |
Therealporkchop
Intermediate Member
Username: Therealporkchop
Post Number: 498
Registered: 11-2002
| | Posted on Friday, December 02, 2005 - 10:42 pm: |
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Yeap. One leg of the emitter is shot for sure. Probably just one transistor. Talk on it until you burn up the other one, then replace them at the same time.
That is if the signal is clear. |
