Is converting these over to 11 meters pretty easy or do I need to have it done by someone who knows exactly what they are doing. I would hate to butch my $4000 xmas present to myself! LOL,
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I bought a brand new Ameritron AL-1500
- Thread starter psycho
- Start date
I have read that there is a green wire to clip to put the amp on10 meters(on most or all of the Ameritron tube type amplifiers). I believe that it grounds the "Aux" input tuning coil and clipping the wire makes the coil active when the band selector is in the 10 meter position.
I have also read that tuning the input coil-meant for the 10 meter position- gives less than stellar performance on 11 meters. A work around would be to buy an extra coil for the 15/17 meter position and modify it so that it will tune on 11 meters. Taking turns of wire off the coil so that it has more turns on it than the 10 meter input tuning coil and less than the 15/17 meter input tuning coil, test the amp, lather, rinse and repeat.
psycho,
I have not owned an Ameritron amp (but have been thinking I NEED one lately- AL80B) but I do believe this information sounds plausible and has some merit. Perhaps others can/will chime in.
Sounds like you have had a very Merry Christmas!!!
73's
David
I have also read that tuning the input coil-meant for the 10 meter position- gives less than stellar performance on 11 meters. A work around would be to buy an extra coil for the 15/17 meter position and modify it so that it will tune on 11 meters. Taking turns of wire off the coil so that it has more turns on it than the 10 meter input tuning coil and less than the 15/17 meter input tuning coil, test the amp, lather, rinse and repeat.
psycho,
I have not owned an Ameritron amp (but have been thinking I NEED one lately- AL80B) but I do believe this information sounds plausible and has some merit. Perhaps others can/will chime in.
Sounds like you have had a very Merry Christmas!!!
73's
David
Green wire on the input band switch like all the other Ameritrons. It should be behind the front panel of that one. It's towards the rear on the smaller ones like the al80b.
The aux position is for 10 thru 12m. The green wire just grounds that coil out and shunts the drive to ground. The 8877 is a fine tube but fragile. Watch the grid current.
The aux position is for 10 thru 12m. The green wire just grounds that coil out and shunts the drive to ground. The 8877 is a fine tube but fragile. Watch the grid current.
Merry Christmas to you ,psycho ! Your killing me here ! That's on my Wish list !
It is important to remember the loading must be set properly for the PEAK power the amplifier is expected to develop. 50 watts PEP will be the maximum drive the amplifier will safely handle if the output of the amplifier is tuned with 50 watts of carrier drive. Any attempt to go beyond the amount of drive power the amplifier was originally tuned at will result in a rapid increase in grid current, splatter and even damage to components.
CPI/Eimac tube rating states...CLASS C Operation (AM/FM/CW) 2400 volts (AL-1500 switch set to CW) and 25 watts drive = 1000 watts PEP
Nice amp, will take a beating, but have seen several op's using them on AM service that have killed the tube in no time. $1100+ mistake running them in SSB with higher plate voltage and trying to drive them using AM with 70-100 PEP watts drive...
All the Best
Gary
https://www.cpii.com/docs/datasheets/213/3CX1500A7-8877.pdf
CPI/Eimac tube rating states...CLASS C Operation (AM/FM/CW) 2400 volts (AL-1500 switch set to CW) and 25 watts drive = 1000 watts PEP
Nice amp, will take a beating, but have seen several op's using them on AM service that have killed the tube in no time. $1100+ mistake running them in SSB with higher plate voltage and trying to drive them using AM with 70-100 PEP watts drive...
All the Best
Gary
https://www.cpii.com/docs/datasheets/213/3CX1500A7-8877.pdf
CW mode for AM, the toob runs mucho cooler. If you use AM and can live with the noise wire the blower for high while you're in there clipping the green wire. The manual has the info.
The chineese 8877s seem to be ok. I run a pair of them that cost me less than $300 each. I have another one set back for the day my 3cx1200a7 lays down.
The chineese 8877s seem to be ok. I run a pair of them that cost me less than $300 each. I have another one set back for the day my 3cx1200a7 lays down.
I have both an AL-82 and AL-1500 and do not run them on 11 meter am. Here is a picture of 80 meter LSB into my dummy load (IC-7610 driving) showing grid current on the right and power out on the left with about 45 watts of drive. The PO meter on the Ameritron is stingy by a good 200 watts as compared to my Alpha 4510a watt meter. As has been mentioned GRID CURRENT is everything. My 8877 (Eimac) is the same tube since Feb 2013 and the output has not changed. When finished tuning you can dip the load control and drop the grid current some.
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There is a HV modification for at least the AL-82 and AL-1500. The problem with the bigger Ameritron amplifiers are the caps capacity. From the factory they supply 8 caps rated for a total of 3700 volts. HV typically runs 3600 to 3700 volts at idle. When the caps/bleeder resistors go bad you’ll hear a snap crackle pop and both fuses will blow. Lou King of QRO W1QJ and another amateur have a replacement board with 4500 volt capacity.
The HV modification involves using the green wire off the transformer. I’ve attached a picture of the discussion. This will raise your HV to 4000 volts.
Ameritron’s website mentions 65 watts of drive and the literature states 100 watts max input. I’ve driven my al-1500 to 2350 with about 65 watts of drive.
If you’re patient you can find replacement 8877/YU-209/3CX1500 NOS for around 600 to 800 dollars. I just sold a NOS Eimac YU-209(heavy duty version of the 8877) brand new for $600 yesterday. Personally the 3-500z is a more fragile tube than the 8877 although cheaper to replace but not as capable regarding output.
The nice thing about Ameritron amplifiers is they’re easy to work on/fix if necessary. The parts are also currently manufactured as opposed to older Alpha amps which is why I sold my 76CA and 91b before they died.
PS: Congrats on the great amplifier. You won’t be disappointed
The HV modification involves using the green wire off the transformer. I’ve attached a picture of the discussion. This will raise your HV to 4000 volts.
Ameritron’s website mentions 65 watts of drive and the literature states 100 watts max input. I’ve driven my al-1500 to 2350 with about 65 watts of drive.
If you’re patient you can find replacement 8877/YU-209/3CX1500 NOS for around 600 to 800 dollars. I just sold a NOS Eimac YU-209(heavy duty version of the 8877) brand new for $600 yesterday. Personally the 3-500z is a more fragile tube than the 8877 although cheaper to replace but not as capable regarding output.
The nice thing about Ameritron amplifiers is they’re easy to work on/fix if necessary. The parts are also currently manufactured as opposed to older Alpha amps which is why I sold my 76CA and 91b before they died.
PS: Congrats on the great amplifier. You won’t be disappointed
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Thanks for all the comments! DIY is now out of the question and when the retailer gets the amp in they will do the modifications I borught a copy of this thread to them and they will accommodate me! Thanks!
To do it the best way ain't cheap.........now to schedule a tower service to take down and replace my 5 element that was hurt by the last $%##@*^&$ hurricane.
To do it the best way ain't cheap.........now to schedule a tower service to take down and replace my 5 element that was hurt by the last $%##@*^&$ hurricane.
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