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Swan 1200-W 31LQ6 conversion Question

R

RichardHartman

Active Member
Feb 7, 2019
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I have a gentleman that has a Swan 1200-w with 4 31LQ6 tubes. The manual states it has 4 6LQ6 tubes. I think it stated it needed 100-125 w of drive and would do 1200 w peak on SSB. I am interested in purchasing this from him as it covers 80-10 meters. Im assuming the 4 31LQ6's was a conversion done for cost of the tubes. Can anyone help with with two questions?

Is this amp a good choice for 80-10m or was this a cb amp that I shouldn't mess with?

What kind of rating can I expect to see from the 4 31LQ6's?

Any info would be greatly appreciated,

73
 

Here is some info you can use, PDF file.
Sounds like they switched the 6 volt heater tubes for 31 volts and rewired.
1200 watts is way too much to ask of 4 sweep tubes.

73
Jeff
 

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  • swan_1200w_input_systems_short_version__1_.pdf
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Yes, that amp has been modified...YUK...
600 watts PEP OUTPUT (about 400 w on 10m) is where that amp should be operated.
(Drive should be adjusted to achieve this output)
The 1200-watt PEP is the input rating.
Best tube replacement IF it was not mortified, would be 6MJ6/6LQ6
 
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BJ radionut said:

This is not a good amplifier to be used with a modern transceiver as most production models DID NOT have a tuned input circuit!
So, transceiver would need to have an internal tuner.
I would also use a keying buffer/interface to protect the radio.
All the Best
Gary
Click to expand...
Agree Gary, with radios like the old FT101 you did not need a tuned input, but most SS transceivers will not like to work into the input.

73
Jeff
 
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There were some versions of the Swan 1200 that came out with 8950 tubes. I wonder if this was one of those?
Thus, the crazy 31-volt filament LQ6's since that transformer in this version did not have 6-volt windings. By-pass the 12-volt windings and insert this crazy solution.
Then wire the filaments in series off the 120-volt AC house voltage
Stay Clear in my book of this amp... too many questions on why/how that silly tube has been inserted.
All the Best
Gary
 
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AudioShockwav said:
Agree Gary, with radios like the old FT101 you did not need a tuned input, but most SS transceivers will not like to work into the input.

73
Jeff
Click to expand...
Thank you. I have added some pics here maybe it will help someone else in their 20220219_163252.jpg20220219_163312.jpg20220219_163319.jpg20220219_163327.jpg20220219_163342.jpg20220219_163433.jpg20220219_163528.jpg20220219_163546.jpg20220219_163615.jpg adventures. It does look like they added a relay to use with a foot pedal maybe?
 
Yes, BUT hard to tell/could be part of the tube mod...
See those dark gray(black) marks on bottom of chassis...BLOW UP marks... PLUS Chassis has been near moisture or near coastal waters(salt), hence dark freckles on outside /inside...
Richard...hope you did not purchase... :-(
or paid very little like $100...if I had bought that...going to take several hundred $$$ dollars to get where I would feel safe using it has been severely hacked... SORRY
IMHO
All the Best
Gary
 
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BJ radionut said:
Yes, BUT hard to tell/could be part of the tube mod...
See those dark gray(black) marks on bottom of chassis...BLOW UP marks... PLUS Chassis has been near moisture or near coastal waters(salt), hence dark freckles on outside /inside...
Richard...hope you did not purchase... :-(
or paid very little like $100...if I had bought that...going to take several hundred $$$ dollars to get where I would feel safe using it has been severely hacked... SORRY
IMHO
All the Best
Gary
Click to expand...
I do appreciate the feedback. I did not purchase this unit as I decided it was not ideal for me. It is nice to have a community that can help avoid making bad decisions. I do have possession of the unit because the owner doesn't know much about it either. So I thought maybe could get some good advice/info here.

Thanks again,

73
KC8DVE
 
Not any more...The cost on repair of many, just does not result in good results...
I work on my own stuff for that very reason.
How much you looking to spend on amp?
I'll keep my ear to ground!
Roger at R & L Electronics nr Cincy has amps at times, but just never know...He sells a ton of gear!

R&L Electronics

Amateur Radio Store, Ham Radio Store
www.randl.com

HAMVENTION is coming at XENIA, OH in May ...if you can't find a deal there...you never will.

Home - Hamvention

hamvention.org hamvention.org
Indy has a fest in July normally also.
73
All the Best
Gary
 
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BJ radionut said:
Not any more...The cost on repair of many, just does not result in good results...
I work on my own stuff for that very reason.
How much you looking to spend on amp?
I'll keep my ear to ground!
Roger at R & L Electronics nr Cincy has amps at times, but just never know...He sells a ton of gear!

R&L Electronics

Amateur Radio Store, Ham Radio Store
www.randl.com

HAMVENTION is coming at XENIA, OH in May ...if you can't find a deal there...you never will.

Home - Hamvention

hamvention.org hamvention.org
Indy has a fest in July normally also.
73
All the Best
Gary
Click to expand...
I appreciate the info Gary. At this time I have what I need. I like the look of the Swan cabinet and it interested me at first, you know that piece that will set on the shelf for looks!. I just don't know anything about tube amp's so needed to ask.

73
 

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