I have an older sweep tube amp in 1x3 configuration using 6je6's. Given the availability and cost of NOS tubes for this, what is the feasibility of re-tubing this with something more readily available like EL509/519's, or maybe 572B's? (Although I suspect I don't have the voltage required by some of the big glass.) Doesn't have to remain in the same config. I'm not looking for a huge wattage increase (no, I don't play on the Supabowl, 10-4, Rogeee..... :roll: ), just something in the 180-250W range would be adequate, any more than that would just be icing on the cake. Any thoughts on the subject? Suggestions? I have a feeling that the cost to re-invent the wheel is going to be not worth the effort, but I hate to give up on an amp that's almost mint except for the tubes. Am I beating a dead horse here? TIA
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Sweep Tube Amp Question
- Thread starter PA629
- Start date
PA629 said:
Answer coming from someone who know`s just enough to be
Dangerous :shock: I would say that You pretty much
answered all of your own questions as to this one...
Regards,
Toll_Free
Well-Known Member
PA629 said:
Wth the typical sweep tube amp, for bullet proof operation AFTER conversion, this is what I did 10 years ago.
If it has a straight HV PS, convert to a doubler to get app 1700 volts DC. Put in 811As.. A pair of them = 4 sweep tubes, more or less... More like 3 = 4 sweep tubes, but... Hey, who's counting.
You will need to change out the plate blocking cap and usually the plate tune cap. If you KNOW HOW to tune your amp, you won't need to change out the ant load cap, since the voltage across it shouldn't change that much.
As to drive, you will need more drive. Tuned input can help, but a pair of 811s need more than a typical CB for drive. Messenger AM 30 works nice, as do some of the junk italian amps now on the market. Honestly, a Palomar 300A converted to 3 811s was driven REALLY nicely by a 300A in low gear, with an AM30 modulator driving it. > 700 watts PEP output, 650 of
that swing
Today, I wouldn't bother. Get a used 811 or 572b amp and be done with it. They can be found for a couple hundred bucks on the amateur swap nets. Add a TS Mod Plus and you have an ASS KICKING 11 meter station.
--Toll_Free
Thanks to the people who PM'd me and posted replies to my questions, I've got a better idea on which direction to go. I have an SB-220 available for use after we finish a wiring upgrade this Spring as part of a larger remodeling project on the ol' Homestead. Was hoping for an easy fix on the sweep tuber in the interim. If I ever get any conditions for DX around here, I can always throw a 100W mobile amp on a power supply, should be enough on a 2 element quad.
BTW, interesting Forum here. Definitely some knowledgeable folks. Glad I found it. 8)
BTW, interesting Forum here. Definitely some knowledgeable folks. Glad I found it. 8)
Toll_Free
Well-Known Member
PA629 said:
If you're going to run the SB220 next summer, then you can do the following.
Have your 1-3 fixed up, and set it up to be a 1-3 on high side. Low side, just the 3.
The, you can run the thing on low gear, it should get you a easy 100 to 150 pep and drive the SB220 REALLY well.
The SB220 can be modified to produce more power, PEP, easily. It slides it to true class B, especially when you take into account the higher line voltages that we have today Vs. the line voltages on when it was 'designed'.
Hope this gives ya a clearer picture. As long as you can get the 1-3 going 150 pep or less, its a nice driver for the sb220.
When things get REALLY hectic, the SB220 can be reworked for more output by driving it with nearly 300 pep.
--Toll_Free
That's roughly what I have in mind. I understand I can get my 1x3 retubed with 31LQ6's. I'm slowly getting my station set up after an aprox. 10 year layoff. Have one tower up now with a homebrew vertical 2 element quad and an A99 for an omni. Another good weather project is putting up the 2nd tower with a flatside yagi, most likely a 4 element. Have to see what all parts I have in the garage attic from the old days. Have a Cobra 2000 for a base now, with a 142GTL, and a 3 button Washington as back-up. I might have a line on an FT-101E from a local Ham, but that's still up in the air. Just picking away at projects as time and money allow, gearing up for next cycle........ 8)
amps
currently i have a firebird 500 1 driving 3 6lq6s which oddly on pep rating on my meter claims keying 300 swinging 1100 i find this inconsiveable....but i try to use the 500 watt setting and i peg it instantly on mod..... anyhow whats the real output around? this meter was very reliable previously.... i just dont see how it could produce that power. but my main question was what must be done to those heathkits 230,220,etc to use with cb? ie keying circuit etc? is it easily accomplished? and how? and where can i find these amps at reasonable cost? the ones on ebay are way to rich for my blood....600 bucks yikes! also would switching to those type amps fix my bleed problems i have with the firebird?
currently i have a firebird 500 1 driving 3 6lq6s which oddly on pep rating on my meter claims keying 300 swinging 1100 i find this inconsiveable....but i try to use the 500 watt setting and i peg it instantly on mod..... anyhow whats the real output around? this meter was very reliable previously.... i just dont see how it could produce that power. but my main question was what must be done to those heathkits 230,220,etc to use with cb? ie keying circuit etc? is it easily accomplished? and how? and where can i find these amps at reasonable cost? the ones on ebay are way to rich for my blood....600 bucks yikes! also would switching to those type amps fix my bleed problems i have with the firebird?
lonestarbandit,
I think I have to agree with you, those kind of readings just are not very likely at all. Can't say what the problem is but there's not much doubt that there is a problem, right?
All the 'HeathKit' amplifiers use 'hard-keying', a switch of some kind, some where, no 'RF-keying'. So, the simplest way to go about it is to provide a switch to turn on the amplifier. That switch can be a foot-switch, a switch/relay activated by the mic button, bunch of possibilities there. Take your choice.
Converting a 'HeathKit' for CB use means that you'll probably have to retune the 10 meter circuitry. Not all that difficult, just don't tear into it unless you know what you are doing.
And one last thing. The voltages found inside of a 'tube' amplifier such as the '230's, '220's etc, will kill you. Not ~can~, but will! Taking the cover off of one is NOT something you should do lightly. The "one hand in the pocket" 'rule' is a very good one...
- 'Doc
(That "hand in the pocket" should always be empty. Holding something with that hand means that you could do more non-fatal damage to yourself than the amplifier can )
I think I have to agree with you, those kind of readings just are not very likely at all. Can't say what the problem is but there's not much doubt that there is a problem, right?
All the 'HeathKit' amplifiers use 'hard-keying', a switch of some kind, some where, no 'RF-keying'. So, the simplest way to go about it is to provide a switch to turn on the amplifier. That switch can be a foot-switch, a switch/relay activated by the mic button, bunch of possibilities there. Take your choice.
Converting a 'HeathKit' for CB use means that you'll probably have to retune the 10 meter circuitry. Not all that difficult, just don't tear into it unless you know what you are doing.
And one last thing. The voltages found inside of a 'tube' amplifier such as the '230's, '220's etc, will kill you. Not ~can~, but will! Taking the cover off of one is NOT something you should do lightly. The "one hand in the pocket" 'rule' is a very good one...
- 'Doc
(That "hand in the pocket" should always be empty. Holding something with that hand means that you could do more non-fatal damage to yourself than the amplifier can
)Re: amps
They can be pricey on eBay but you might find some bargains at your local Hamfest. As Doc has stated, a footswitch, switch/relay is all that is needed to key the amp.
lonestarbandit said:
They can be pricey on eBay but you might find some bargains at your local Hamfest. As Doc has stated, a footswitch, switch/relay is all that is needed to key the amp.
firebird 500
well had it on a second meter not owned by me.... surprise!!!!! it says im swinging pep of 1200~ wtf over!
well had it on a second meter not owned by me.... surprise!!!!! it says im swinging pep of 1200~ wtf over!
got it figured out lol. second order harmonics....causing cb power meters to show double the power. quality low pass filter in place viola 600 pep.
[quote="W5LZ"(That "hand in the pocket" should always be empty. Holding something with that hand means that you could do more non-fatal damage to yourself than the amplifier can )[/quote]
So I take it then that a beer can would not be a good idea.
)[/quote]So I take it then that a beer can would not be a good idea.
W5LZ said:
I missed the hand in the pocket thing.
I meant holding a beer INSTEAD of having your hand in your pocket . See,that's what I get for posting after 27 hours without sleep.I came home this morning after my last night shift and once again I stayed up.I should have slept but instead I bought 4 new tires for my vehicle.There goes this week's pay cheque.Overtime included. 
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