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#21
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Hammarlund SP-210 ?
"Richard Knoppow" wrote in message m... "Henry Kolesnik" wrote in message ... The civilian operating manual I mentioned in another post is to be found at: http://www.hammarlund.info/hamrmanu.html along with a great deal of other Hammarlund stuff. -- -- Richard Knoppow Los Angeles WB6KBL |
#22
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Hammarlund SP-210 ?
Michael Black wrote:
And of course, one commonly written about trick in the old days was to use a "useless" 400Hz transformer as an audio transformer, the operating frequency being about where you'd want frequency response to start for communication use. Since it moves the frequency up by six, the frequency response is probably better at the higher frequencies. That's only a useful trick, though, when 400Hz power transformers are commonly available, and cheap because nobody can find a use for them. I still see PLENTY of 400 Hz transformers coming out of the surplus pipeline today, not to mention 400 Hz motors and brick power supplies. You want some? I think I even have a box of 400 Hz fluorescent light ballasts somewhere. Not even a little bit useful. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#23
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Hammarlund SP-210 ?
I haven't tested the impedance yet, need to find a pot, but I noticed
that the two 6F6es are connected as push pull triodes. I wonder why they didn't use a pair of 45s? Hank "Scott Dorsey" wrote in message ... Henry Kolesnik wrote: Getting old is not recalling the alternatives offered, so I'm a dummy. I found the filament xfmr first and tried it but it reduced volume so I assume my radio which is non-military doesn't have 600 ohms like the military manual I have. So I guess mine is commercial, either a SP-200-SX or more likely a SP-210-SX and I think it has a 3.2 ohm output transformer. I can't find any info and I wonder if anyone knows for sure on the commercial models output transformer's impedance. What is the DC resistance across the output? If you want to know FOR SURE, put the output on a scope with a 1K pot in parallel with it... tune to interchannel noise, and note the location of the peaks on the scope. Crank the pot up until the level is exactly half of what it was, then measure the value of the pot. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#24
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Hammarlund SP-210 ?
"Henry Kolesnik" wrote in message ... I haven't tested the impedance yet, need to find a pot, but I noticed that the two 6F6es are connected as push pull triodes. I wonder why they didn't use a pair of 45s? Hank The 6F6 was a much newer tube at the time and is a metal, octal base, tube. It has sufficient plate dissipation and works well as a triode audio amp. The 45 also has 2.5V a filament and is not a heater type cathode, meaning that it needs a DC filiment source for audio use. Triode audio amps have lower source impedance than tetrodes when used without feedback which is an advantage in driving variable load impedances like loudspeakers, and generally more pleasant overload characteristics. The 6F6 was a good choice at the time and could also be used as a driver. -- -- Richard Knoppow Los Angeles, CA, USA |
#25
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Hammarlund SP-210 ?
Rich
45s don't need DC for the filament... They have been working fine on AC for years! Hank "Richard Knoppow" wrote in message m... "Henry Kolesnik" wrote in message ... I haven't tested the impedance yet, need to find a pot, but I noticed that the two 6F6es are connected as push pull triodes. I wonder why they didn't use a pair of 45s? Hank The 6F6 was a much newer tube at the time and is a metal, octal base, tube. It has sufficient plate dissipation and works well as a triode audio amp. The 45 also has 2.5V a filament and is not a heater type cathode, meaning that it needs a DC filiment source for audio use. Triode audio amps have lower source impedance than tetrodes when used without feedback which is an advantage in driving variable load impedances like loudspeakers, and generally more pleasant overload characteristics. The 6F6 was a good choice at the time and could also be used as a driver. -- -- Richard Knoppow Los Angeles, CA, USA |
#26
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Hammarlund SP-210 ?
"Henry Kolesnik" wrote in message ... Rich 45s don't need DC for the filament... They have been working fine on AC for years! Hank Well, an ancient RCA tube handbook does list the 45 as being for AC operated sets. It needs a center tapped filiment transformer for cathode return although it could be done with a center tapped resistor across the filiment. The 45 (AKA RCA UV-245) was an old and obsolete design when the Super Pro was designed. Why do you think this tube is superior to trioded connected 6F6's? -- -- Richard Knoppow Los Angeles WB6KBL |
#27
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Hammarlund SP-210 ?
Richard
I don't know if the 45 triode is superior to a triode connected 6F6, I was just wondering out loud at the keyboard. I know that audio aficinianodos like 45s in class A but this is PP, B. It was a thought that shouldn'thave made it to the keyboard, hi hi.. I took the beast to the hamfest but only found lookers and knob twisters. Now I have the back breaking chore of bringing back to the bench and checking the audio PP xfmr. Hank "Richard Knoppow" wrote in message ... "Henry Kolesnik" wrote in message ... Rich 45s don't need DC for the filament... They have been working fine on AC for years! Hank Well, an ancient RCA tube handbook does list the 45 as being for AC operated sets. It needs a center tapped filiment transformer for cathode return although it could be done with a center tapped resistor across the filiment. The 45 (AKA RCA UV-245) was an old and obsolete design when the Super Pro was designed. Why do you think this tube is superior to trioded connected 6F6's? -- -- Richard Knoppow Los Angeles WB6KBL |
#28
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Hammarlund SP-210 ?
I just recalled I have a GR 583-A Output Power Meter wasting gravity and
if it still works I'll have the answer. If you Google it, you'll see the one Sphere has for sale. Thanks for all the comments. Hank "Scott Dorsey" wrote in message ... Henry Kolesnik wrote: Getting old is not recalling the alternatives offered, so I'm a dummy. I found the filament xfmr first and tried it but it reduced volume so I assume my radio which is non-military doesn't have 600 ohms like the military manual I have. So I guess mine is commercial, either a SP-200-SX or more likely a SP-210-SX and I think it has a 3.2 ohm output transformer. I can't find any info and I wonder if anyone knows for sure on the commercial models output transformer's impedance. What is the DC resistance across the output? If you want to know FOR SURE, put the output on a scope with a 1K pot in parallel with it... tune to interchannel noise, and note the location of the peaks on the scope. Crank the pot up until the level is exactly half of what it was, then measure the value of the pot. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#29
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Hammarlund SP-210 ?
"Henry Kolesnik" wrote in message ... I just recalled I have a GR 583-A Output Power Meter wasting gravity and if it still works I'll have the answer. If you Google it, you'll see the one Sphere has for sale. Thanks for all the comments. Hank That will definitely give you the output impedance but be careful not to overload it. There is something odd about this. My BC-779 is in storage so I can't make resistance measurements on the transformer. I think its time to dig it out though. I am afraid many people simply don't know what the Super-Pro is or how good they are. What part of the world are you in? -- -- Richard Knoppow Los Angeles WB6KBL |
#30
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Hammarlund SP-210 ?
Mine's in the trunk from the last hamfest with the power supply
connected so I have to carry both at once, the ps on top. I'll get to it tomorrow, too many other things today.. I'm in Tulsa, OK Hank "Richard Knoppow" wrote in message m... "Henry Kolesnik" wrote in message ... I just recalled I have a GR 583-A Output Power Meter wasting gravity and if it still works I'll have the answer. If you Google it, you'll see the one Sphere has for sale. Thanks for all the comments. Hank That will definitely give you the output impedance but be careful not to overload it. There is something odd about this. My BC-779 is in storage so I can't make resistance measurements on the transformer. I think its time to dig it out though. I am afraid many people simply don't know what the Super-Pro is or how good they are. What part of the world are you in? -- -- Richard Knoppow Los Angeles WB6KBL |
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