|
Hammarlund SP-210 ?
I ended up with this & it's separate power supply in a package deal,
couldn't buy what I wanted without taking it. It looks better than average but doesn't have the original S-meter. Both are rack mount units in cases with a heavy interconnecting cable, and they are heavy! It covers 1.25 to 40 Mc in 5 bands. Both units have aluminum tags with serial numbers and the Rx is stamped Type O with a 40,000 serial. I've heard that they have terrific audio but with only a portion of BCB it's a bummer. I'd like to know a bit more about it and if they have any value as collectors items or are they true boat anchors? Is it a BC-794 A or B or a SP-210-SX or what? Why did they make the power supply so heavy? Thanks -- 73 Hank WD5JFR |
Hammarlund SP-210 ?
I own one. Has little collector value - they made too many. Certainly
a very good boatanchor receiver for AM - in a class with R390, HRO50/60 IMHO. No product detector so not good for SSB without an add in prod detector. Terry W8EJO |
Hammarlund SP-210 ?
Hi Terry
Got any idea which model I might have? Back in the 50s when I was a kid I would have given anything to have one. And I only saw one real one, the rest were in pictures! -- 73 Hank WD5JFR "Nomad" wrote in message ... I own one. Has little collector value - they made too many. Certainly a very good boatanchor receiver for AM - in a class with R390, HRO50/60 IMHO. No product detector so not good for SSB without an add in prod detector. Terry W8EJO |
Hammarlund SP-210 ?
On Oct 22, 1:43*pm, "Henry Kolesnik"
wrote: Hi Terry Got any idea which model I might have? *Back in the 50s when I was a kid I would have given anything to have one. *And I only saw one real one, the rest were in pictures! -- 73 Hank WD5JFR"Nomad" wrote in message ... I own one. Has little collector value - they made too many. Certainly a very good boatanchor receiver for AM - in a class with R390, HRO50/60 IMHO. No product detector so not good for SSB without an add in prod detector. Terry W8EJO See this site for model ID: http://www.skywaves.ar88.net/commrx/...-Pro_Data.html and http://www.radiomuseum.org/forum/cro... ceivers.html and this site for info: http://www.skywaves.ar88.net/commrx/...Pro_SP-10.html If you need a manual they are also available online. |
Hammarlund SP-210 ?
On Wed, 22 Oct 2008 11:33:14 -0500, Henry Kolesnik wrote:
I ended up with this & it's separate power supply in a package deal, couldn't buy what I wanted without taking it. It looks better than average but doesn't have the original S-meter. Both are rack mount units in cases with a heavy interconnecting cable, and they are heavy! It covers 1.25 to 40 Mc in 5 bands. Both units have aluminum tags with serial numbers and the Rx is stamped Type O with a 40,000 serial. I've heard that they have terrific audio but with only a portion of BCB it's a bummer. I'd like to know a bit more about it and if they have any value as collectors items or are they true boat anchors? Is it a BC-794 A or B or a SP-210-SX or what? Why did they make the power supply so heavy? Thanks Yours should be a SP-210-SX or BC-794-B (1.25 - 40 MHz) More info at: http://www.roveroresearch.org/sp200/bc779.html |
Hammarlund SP-210 ?
"PJR" wrote in message news:XpmdncIb_cmzlJzUnZ2dnUVZ_rmdnZ2d@metrocastcab levision.com... On Wed, 22 Oct 2008 11:33:14 -0500, Henry Kolesnik wrote: I ended up with this & it's separate power supply in a package deal, couldn't buy what I wanted without taking it. It looks better than average but doesn't have the original S-meter. Both are rack mount units in cases with a heavy interconnecting cable, and they are heavy! It covers 1.25 to 40 Mc in 5 bands. Both units have aluminum tags with serial numbers and the Rx is stamped Type O with a 40,000 serial. I've heard that they have terrific audio but with only a portion of BCB it's a bummer. I'd like to know a bit more about it and if they have any value as collectors items or are they true boat anchors? Is it a BC-794 A or B or a SP-210-SX or what? Why did they make the power supply so heavy? Thanks Yours should be a SP-210-SX or BC-794-B (1.25 - 40 MHz) More info at: http://www.roveroresearch.org/sp200/bc779.html An interesting site. There were more military variations on the Super-Pro than shown, for instance, there was a modification that allowed the use of crystal control for fixed frequency operation. The crystal unit was mounted behind the main tuning dial with two knobs projecting above the dial, one for crystal selection and the other for fine tuning just as in the SP-600. These were evidently used in diversity operation with two or three receivers being linked together. While most of the drift will be over in half an hour it really takes many hours for the receiver to stablize, perhaps 12 hours. They were meant for continuous operation and will not drift much when so operated. It has been a puzzle to me that Hammarlund did not use voltage regulators for the later Super-Pro's not even the SP-400, even though they did use them in the comtemporaneous HQ-100 and had the knowledge. The HQ-and its later versions, also had temperature compensation. Perhaps the temperature compensation would have required too much redesign of the very complex tuning unit but voltage regulation would have required little and is easily applied to existing receivers. Some of the war time receivers, notably the Howard-built ones have some other variations, probably due to shortage of parts. For instance toggle switches are used for the BFO switch instead of a rotary switch. Makes no difference to operation but doesn't look as nice. One somewhat obscure effect of the high quality audio circuit is that static and interference are less bothersom because the audio circuit is not exagerating them with distortion. Most tube communication receivers have very simple, single-ended, pentode output stages with no feedback. The are big time distortion producers. The difference is easily heard in a direct comparison. For instance, for a receiver like the SP-600 which has a detector output listening to this output on a good quality external amplifier in comparison to the receiver's own amplifier is night and day. Its interesting that the original ads for the SP-600, based on a developmental model, indicate it had push-pull audio. I rather think that the desire to put the entire receiver, including the power supply, on a single chassis required some serious compromises including dropping the push-pull circuit. The two chassis arrangement of the older Super-Pro's allows room for the quite large audio stage, comprising three tubes and two rather large transformers. Some other receivers of the time also had push-pull amplifiers, notably the SX-28 and SX-32, SX-27, SX-36 and the National NC-100, NC-200 and later versions, and the HRO-50 and 60. Even though the National receivers have rather narrow IF's the lack of distortion makes a difference as noted above. This is not an exhaustive list, there were a number of other receivers with high quality audio stages. Many had a jack for a crystal phonograph pickup in order to get double duty from the audio stage. The Super Pro is a favorite of mine as you can probably tell:-) -- Richard Knoppow Los Angeles WB6KBL |
Hammarlund SP-210 ?
What's an easy way these days with limited audio xfrmrs around to get
the 600 ohm spkr output to 4 or 8 ohms? -- Thanks & 73 Hank WD5JFR "Richard Knoppow" wrote in message ... "PJR" wrote in message news:XpmdncIb_cmzlJzUnZ2dnUVZ_rmdnZ2d@metrocastcab levision.com... On Wed, 22 Oct 2008 11:33:14 -0500, Henry Kolesnik wrote: I ended up with this & it's separate power supply in a package deal, couldn't buy what I wanted without taking it. It looks better than average but doesn't have the original S-meter. Both are rack mount units in cases with a heavy interconnecting cable, and they are heavy! It covers 1.25 to 40 Mc in 5 bands. Both units have aluminum tags with serial numbers and the Rx is stamped Type O with a 40,000 serial. I've heard that they have terrific audio but with only a portion of BCB it's a bummer. I'd like to know a bit more about it and if they have any value as collectors items or are they true boat anchors? Is it a BC-794 A or B or a SP-210-SX or what? Why did they make the power supply so heavy? Thanks Yours should be a SP-210-SX or BC-794-B (1.25 - 40 MHz) More info at: http://www.roveroresearch.org/sp200/bc779.html An interesting site. There were more military variations on the Super-Pro than shown, for instance, there was a modification that allowed the use of crystal control for fixed frequency operation. The crystal unit was mounted behind the main tuning dial with two knobs projecting above the dial, one for crystal selection and the other for fine tuning just as in the SP-600. These were evidently used in diversity operation with two or three receivers being linked together. While most of the drift will be over in half an hour it really takes many hours for the receiver to stablize, perhaps 12 hours. They were meant for continuous operation and will not drift much when so operated. It has been a puzzle to me that Hammarlund did not use voltage regulators for the later Super-Pro's not even the SP-400, even though they did use them in the comtemporaneous HQ-100 and had the knowledge. The HQ-and its later versions, also had temperature compensation. Perhaps the temperature compensation would have required too much redesign of the very complex tuning unit but voltage regulation would have required little and is easily applied to existing receivers. Some of the war time receivers, notably the Howard-built ones have some other variations, probably due to shortage of parts. For instance toggle switches are used for the BFO switch instead of a rotary switch. Makes no difference to operation but doesn't look as nice. One somewhat obscure effect of the high quality audio circuit is that static and interference are less bothersom because the audio circuit is not exagerating them with distortion. Most tube communication receivers have very simple, single-ended, pentode output stages with no feedback. The are big time distortion producers. The difference is easily heard in a direct comparison. For instance, for a receiver like the SP-600 which has a detector output listening to this output on a good quality external amplifier in comparison to the receiver's own amplifier is night and day. Its interesting that the original ads for the SP-600, based on a developmental model, indicate it had push-pull audio. I rather think that the desire to put the entire receiver, including the power supply, on a single chassis required some serious compromises including dropping the push-pull circuit. The two chassis arrangement of the older Super-Pro's allows room for the quite large audio stage, comprising three tubes and two rather large transformers. Some other receivers of the time also had push-pull amplifiers, notably the SX-28 and SX-32, SX-27, SX-36 and the National NC-100, NC-200 and later versions, and the HRO-50 and 60. Even though the National receivers have rather narrow IF's the lack of distortion makes a difference as noted above. This is not an exhaustive list, there were a number of other receivers with high quality audio stages. Many had a jack for a crystal phonograph pickup in order to get double duty from the audio stage. The Super Pro is a favorite of mine as you can probably tell:-) -- Richard Knoppow Los Angeles WB6KBL |
Hammarlund SP-210 ?
"Henry Kolesnik" wrote in message ... What's an easy way these days with limited audio xfrmrs around to get the 600 ohm spkr output to 4 or 8 ohms? 120 Volt to 12 Volt power transformer. Good at least down to 50 Hz or better. W4ZCB |
Hammarlund SP-210 ?
Henry Kolesnik wrote:
What's an easy way these days with limited audio xfrmrs around to get the 600 ohm spkr output to 4 or 8 ohms? 70V PA distribution transformers. A 70V distribution transformer with an eight-watt input tap will give you 600 ohms input. Old 70V equipment is usually available free for the asking from your local installed sound company. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Hammarlund SP-210 ?
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. -- Thanks & 73 Hank WD5JFR "Scott Dorsey" wrote in message ... Henry Kolesnik wrote: What's an easy way these days with limited audio xfrmrs around to get the 600 ohm spkr output to 4 or 8 ohms? 70V PA distribution transformers. A 70V distribution transformer with an eight-watt input tap will give you 600 ohms input. Old 70V equipment is usually available free for the asking from your local installed sound company. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Hammarlund SP-210 ?
"Henry Kolesnik" wrote in message ... 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. -- Thanks & 73 Hank WD5JFR All of the Super-Pro models from the SP-100 on had 500 ohm outputs for the loudspeaker and a loosly coupled 8K winding for headphones. The 500 ohm output will drive a loudspeaker at much reduced volume. A 12.6V filiment transformer has about the right impedance ratio (100:1) to drive a 4 to 8 ohm speaker from this tap. These tramsformers have enough core material to work down to low audio frequencies and surprizingly good high frequency response. 70V public address transformers also work very well as Scott Dorsey pointed out. The original Hammarlund speakers for the Sp-200, 400, 600, had matching transformers built-in. The SP-100 has a front panel switch for the loudspeaker but the later versions do not. You need to mount a switch (maybe in the loudspeaker cabinet) to cut it off. Use a DPDT switch with a 500 or 600 ohm resistor switched in when the LS is turned off to provide a load to the audio transformer. It should handle a couple of watts. The headphone winding is not critical of load impedance and will work with phones from 50ohms to high impedance. The military and commercial versions of the SP-200 and 210 were identical except for the use of hermetically sealed transformers and chokes and oil filled filter capacitors in the military versions, and some variations of panel finish. There is an owner's manual for the SP-210 somewhere on the web, maybe on BAMA, I have a copy but don't remember where I downloaded it. Most of the communications receivers built up to perhaps the 1950s had 500 ohm or 600 ohm outputs. A few even had the output transformer in the loudspeaker cabinet. -- -- Richard Knoppow Los Angeles WB6KBL |
Hammarlund SP-210 ?
Richard
The volume decreased with the filament transformer so I need to open it up and see if someone made some mods. I downloaded the military manual. It seems to me that someone at Ham went nuts changing model numbers for very insignificant reasons. "Richard Knoppow" wrote in message m... "Henry Kolesnik" wrote in message ... 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. -- Thanks & 73 Hank WD5JFR All of the Super-Pro models from the SP-100 on had 500 ohm outputs for the loudspeaker and a loosly coupled 8K winding for headphones. The 500 ohm output will drive a loudspeaker at much reduced volume. A 12.6V filiment transformer has about the right impedance ratio (100:1) to drive a 4 to 8 ohm speaker from this tap. These tramsformers have enough core material to work down to low audio frequencies and surprizingly good high frequency response. 70V public address transformers also work very well as Scott Dorsey pointed out. The original Hammarlund speakers for the Sp-200, 400, 600, had matching transformers built-in. The SP-100 has a front panel switch for the loudspeaker but the later versions do not. You need to mount a switch (maybe in the loudspeaker cabinet) to cut it off. Use a DPDT switch with a 500 or 600 ohm resistor switched in when the LS is turned off to provide a load to the audio transformer. It should handle a couple of watts. The headphone winding is not critical of load impedance and will work with phones from 50ohms to high impedance. The military and commercial versions of the SP-200 and 210 were identical except for the use of hermetically sealed transformers and chokes and oil filled filter capacitors in the military versions, and some variations of panel finish. There is an owner's manual for the SP-210 somewhere on the web, maybe on BAMA, I have a copy but don't remember where I downloaded it. Most of the communications receivers built up to perhaps the 1950s had 500 ohm or 600 ohm outputs. A few even had the output transformer in the loudspeaker cabinet. -- -- Richard Knoppow Los Angeles WB6KBL |
Hammarlund SP-210 ?
"Henry Kolesnik" wrote in message ... Richard The volume decreased with the filament transformer so I need to open it up and see if someone made some mods. I downloaded the military manual. It seems to me that someone at Ham went nuts changing model numbers for very insignificant reasons. "Richard Knoppow" wrote in message m... Before you do any surgery make sure the matching transformer is connected the right way around, the 120V winding goes to the 500 Ohm winding on the RX, the filiment winding goes to the loudspeaker. The output transformer would have to be changed to provide a low impedance output, that would be pretty obvious. The headphone output is also brought out the back on the terminal board. -- -- Richard Knoppow Los Angeles WB6KBL |
Hammarlund SP-210 ?
"Henry Kolesnik" wrote in message ... Richard The volume decreased with the filament transformer so I need to open it up and see if someone made some mods. I downloaded the military manual. It seems to me that someone at Ham went nuts changing model numbers for very insignificant reasons. Note that the military type numbering was not done by Hammarlund. The Super-Pro went through three versions, the SP-100, the SP-200, the SP-400. The SP-100 was available in three versions with different frequency ranges, the SP-400 in two ranges. The SP-100 was also available with or without the crystal filter (I've never seen one without) but evidently the filter could be retrofitted. All three were also available in table or rack mount versions. There were at least two power supplies, a standard and a 50 hz supply. The 50hz supply will work on 60hz but not the other way. The last military versions came with solid state power supplies. There are some circuit differences between the different frequency ranges. The standard version and the aircraft frequency version (100 to 400khz) have series fed RF stages with some loading on the low frequency range and broadcast range of the standard version to broaden out the RF bandwidth. The high frequency version (1250khz to 40Mhz) has shunt-fed RF to keep the DC out of the RF coils. The coils have ferrite cores so removing the DC sharpens them up a bit, which is needed for a single conversion receiver operating a the higher part of the frequency range. A similar arrangement is used in the SP-400 and SP-400S (the last has the same 1250 to 40Mhz range). The three frequency range receivers had different military type numbers. The SP-210 is the same as the SP-200 but came with a 10" loudpeaker, there was also a SP-220, again the same chaissis with a 12" speaker. The standard version had an X on the end of the number (SP-210X) indicating it had the crystal filter, the high-frequency coverage version had an S on the model number as well as the X for crystal, vis: SP-210SX. The first versions, the SP-100 had glass multi-pin tubes with external sheilds, the SP-200 was redesigned to use metal octal tubes with do not need external shields. Otherwise the circuits are pretty much the same. The main virtue of the Super-Pro was the band switching arrangement. This is a very complex system of knife edge switches operated by cams, presumably to reduce lead length. National achieved something similar with the plug-in coils on the HRO and the sliding RF box on the NC-100, 101, and later NC-200 and 240 types. This may actually be a better arrangement. Hammarlund caught up by using a rotary turret on the SP-600 and Pro-310. But, except for Hallicrafters version of the Super-Pro, which also has a turret, I don't know of many receivers that used this good, but complex arrangement. One virtue of the Super-Pro is its excellent interstage shielding and lack of spurious responses, probably at least in part due to the RF stage arrangement. It is also a relatively low radiation reciever. Note that both the sliding coil method of adjusting the mutual inductance of the IF stages (and hence bandwidth) and the type of crystal filter circuit were Hammarlund exclusives. The IF bandwidth arrangement allows symmetrical expansion of the response curve where some other methods cause the bandwidth to expand only on one side. The crystal filter is arranged to vary the Q of the loading coil and, again, does not change the center frequency or gain as the bandwidth is changed, plus it uses a butterfly capacitor to adjust the phasing again so the center frequency does not vary with the notch position. This is a much more satisfactory system than the original Lamb filter used on National and Hallicrafters receivers until pretty late in the game. I have the civilian version of the instruction book and will post it to you via private e-mail if you can't find it. I am still on a dial-up and its pretty big but its yours if you desire. BTW, it has a long list of the patents used (mostly RCA and Hazeltine Labs) some of which are interesting to chase down. -- -- Richard Knoppow Los Angeles WB6KBL |
Hammarlund SP-210 ?
Richard
Having the dial up goes with the SP, hi hi. I did connect the 500 to the fil xfrmr pri. I was a GCA tech in he air force, worked as a radio and TV tech in high school and college and am a grad engr and have a bit of experience. And I 've had a few SP 600s but this is my first Super Pro 200. 1.25 to 40 Mcs, xtal filter, S-meter and 60 cps pwr supply and stamped Type O after all the patents. It's kind of a neat boatanchor that I've never played with before and for some unknown reason I keep on playing with it. I wish it had the full BCB but it's nice on CW & SWL. After being on all day I don't notice that much drift. It is just about right on on all the WWVs, but all you know about other frequencies is the first 2 digits. I don't need the manual as I have a copy of a copy of copy and the TM 11-866 but neither is really clear on the model number. I was offered $75 at the last hamfest and maybe I'll be lucky and get closer to the $150.00 I have in it or trade for some other beast. 73 Hank "Richard Knoppow" wrote in message m... "Henry Kolesnik" wrote in message ... Richard The volume decreased with the filament transformer so I need to open it up and see if someone made some mods. I downloaded the military manual. It seems to me that someone at Ham went nuts changing model numbers for very insignificant reasons. Note that the military type numbering was not done by Hammarlund. The Super-Pro went through three versions, the SP-100, the SP-200, the SP-400. The SP-100 was available in three versions with different frequency ranges, the SP-400 in two ranges. The SP-100 was also available with or without the crystal filter (I've never seen one without) but evidently the filter could be retrofitted. All three were also available in table or rack mount versions. There were at least two power supplies, a standard and a 50 hz supply. The 50hz supply will work on 60hz but not the other way. The last military versions came with solid state power supplies. There are some circuit differences between the different frequency ranges. The standard version and the aircraft frequency version (100 to 400khz) have series fed RF stages with some loading on the low frequency range and broadcast range of the standard version to broaden out the RF bandwidth. The high frequency version (1250khz to 40Mhz) has shunt-fed RF to keep the DC out of the RF coils. The coils have ferrite cores so removing the DC sharpens them up a bit, which is needed for a single conversion receiver operating a the higher part of the frequency range. A similar arrangement is used in the SP-400 and SP-400S (the last has the same 1250 to 40Mhz range). The three frequency range receivers had different military type numbers. The SP-210 is the same as the SP-200 but came with a 10" loudpeaker, there was also a SP-220, again the same chaissis with a 12" speaker. The standard version had an X on the end of the number (SP-210X) indicating it had the crystal filter, the high-frequency coverage version had an S on the model number as well as the X for crystal, vis: SP-210SX. The first versions, the SP-100 had glass multi-pin tubes with external sheilds, the SP-200 was redesigned to use metal octal tubes with do not need external shields. Otherwise the circuits are pretty much the same. The main virtue of the Super-Pro was the band switching arrangement. This is a very complex system of knife edge switches operated by cams, presumably to reduce lead length. National achieved something similar with the plug-in coils on the HRO and the sliding RF box on the NC-100, 101, and later NC-200 and 240 types. This may actually be a better arrangement. Hammarlund caught up by using a rotary turret on the SP-600 and Pro-310. But, except for Hallicrafters version of the Super-Pro, which also has a turret, I don't know of many receivers that used this good, but complex arrangement. One virtue of the Super-Pro is its excellent interstage shielding and lack of spurious responses, probably at least in part due to the RF stage arrangement. It is also a relatively low radiation reciever. Note that both the sliding coil method of adjusting the mutual inductance of the IF stages (and hence bandwidth) and the type of crystal filter circuit were Hammarlund exclusives. The IF bandwidth arrangement allows symmetrical expansion of the response curve where some other methods cause the bandwidth to expand only on one side. The crystal filter is arranged to vary the Q of the loading coil and, again, does not change the center frequency or gain as the bandwidth is changed, plus it uses a butterfly capacitor to adjust the phasing again so the center frequency does not vary with the notch position. This is a much more satisfactory system than the original Lamb filter used on National and Hallicrafters receivers until pretty late in the game. I have the civilian version of the instruction book and will post it to you via private e-mail if you can't find it. I am still on a dial-up and its pretty big but its yours if you desire. BTW, it has a long list of the patents used (mostly RCA and Hazeltine Labs) some of which are interesting to chase down. -- -- Richard Knoppow Los Angeles WB6KBL |
Hammarlund SP-210 ?
Harold E. Johnson wrote:
"Henry Kolesnik" wrote in message ... What's an easy way these days with limited audio xfrmrs around to get the 600 ohm spkr output to 4 or 8 ohms? 120 Volt to 12 Volt power transformer. Good at least down to 50 Hz or better. The problem isn't the low end, the problem is the high end. But the ratio is about right, and if you pick a good transformer you'll be okay. Problem is that a lot of cheap transformers have poor core material that leads to a lot of distortion, and a lot of the better transformers are wound to specifically limit the frequency response. For example, the Talema toroids from Digi-Key are great at 60 Hz, but down 6 dB at 500 Hz and keep falling above that. This is a great thing for a power transformer where you don't want to leak noise into the power line or the other way around, but it's a bad thing for audio. But there are a lot of filament transformers out there that are quite reasonable for audio, and they are cheap enough that you can try a whole bunch of them and see which work best. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
Hammarlund SP-210 ?
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." |
Hammarlund SP-210 ?
On Thu, 30 Oct 2008, Scott Dorsey wrote:
Harold E. Johnson wrote: "Henry Kolesnik" wrote in message ... What's an easy way these days with limited audio xfrmrs around to get the 600 ohm spkr output to 4 or 8 ohms? 120 Volt to 12 Volt power transformer. Good at least down to 50 Hz or better. The problem isn't the low end, the problem is the high end. But the ratio is about right, and if you pick a good transformer you'll be okay. 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. Michael VE2BVW |
Hammarlund SP-210 ?
Scott
Good suggestion, I'll try it later and let you know. 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." |
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 |
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." |
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." |
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 |
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 |
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 |
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 |
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." |
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 |
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 |
Hammarlund SP-210 ?
"Henry Kolesnik" wrote in message ... 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... Too bad, just a little too far for me to drive over and get it:-) -- -- Richard Knoppow Los Angeles WB6KBL |
Hammarlund SP-210 ?
Neil Sutcliffe was kind enough to send me a manual on his GR 783A which
is a more recent version of my GR 583A Output Impedance Meter. The o/p xfrmr on my Type O 210 is 10 ohms and I looked inside and saw no evidence that it was change. I confirmed that the meter works by the same technique on my Ten Tec SP 325 which is 600 ohms and it measured 600 ohms. The GR 583A is a neat piece of gear, easy as pie to use. -- Thanks & 73 Hank WD5JFR "Richard Knoppow" wrote in message m... "Henry Kolesnik" wrote in message ... 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... Too bad, just a little too far for me to drive over and get it:-) -- -- Richard Knoppow Los Angeles WB6KBL |
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