Re: [time-nuts] Distribution amp - Use a video amp unit ?
The LMH6702 is one of the few current feedback amplifiers that is stable with a relatively low value (237 ohm) feedback resistor. Its estimated phase noise floor is around -171 dBc/Hz with +13dBm output (and input) in the noninverting 2x configuration with a 50 ohm load and a 50 ohm resistor in series with its output. Thats about 3dBc/Hz less noisy than the measured 10MHz phase noise floor of a OPA653 in the same configuration with the same input and output signal levels. For offsets below about 100Hz the phase noise of an OPA653 is indistinguishable from the noise of measurement setup. The effect of drafts and other air currents on the phase shift of RF transformers is also significant for offsets of around 1Hz or less. Extra thermal mass (encapsulation) and draft shields (even a piece of paper) can work wonders. Bruce Joseph M Gwinn wrote: I have seen National LMH6702 current-feedback video amplifier chips in non-inverting amplifier configuration used to implement a wideband 10 MHz distribution amplifier. Joe From: Charles P. Steinmetzcharles_steinm...@lavabit.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: 03/27/2012 07:28 PM Subject:Re: [time-nuts] Distribution amp - Use a video amp unit ? Sent by:time-nuts-boun...@febo.com Bruce wrote: The above reverse isolation [~35 dB] is about 25dB lower than I would expect. D'oh! Bruce is right -- I calculated the reverse isolation incorrectly. I had only been expecting 40 dB, so I didn't question the result. The breadboard actually measured nearly 63 dB. Stable operation at unity gain is necessary if a feedback capacitor is used. The Miller capacitance of the output transistors sees to that (with an even greater phase margin when a faster transistor is used for Q1). An LM329 has similar noise without the dissipation of the internal heater in the LM399 I know. I just particularly like the 399, and have a pile of them. I rationalize using it in this case by noting that the range of frequencies where phase noise of the DA is important includes sub- to low-Hz frequencies at which thermal effects could make the unheated 329 significantly noisier (though if you keep drafts off both of them, it might not be by a large amount). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Bruce wrote: The above reverse isolation [~35 dB] is about 25dB lower than I would expect. D'oh! Bruce is right -- I calculated the reverse isolation incorrectly. I had only been expecting 40 dB, so I didn't question the result. The breadboard actually measured nearly 63 dB. Stable operation at unity gain is necessary if a feedback capacitor is used. The Miller capacitance of the output transistors sees to that (with an even greater phase margin when a faster transistor is used for Q1). An LM329 has similar noise without the dissipation of the internal heater in the LM399 I know. I just particularly like the 399, and have a pile of them. I rationalize using it in this case by noting that the range of frequencies where phase noise of the DA is important includes sub- to low-Hz frequencies at which thermal effects could make the unheated 329 significantly noisier (though if you keep drafts off both of them, it might not be by a large amount). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I have seen National LMH6702 current-feedback video amplifier chips in non-inverting amplifier configuration used to implement a wideband 10 MHz distribution amplifier. Joe From: Charles P. Steinmetz charles_steinm...@lavabit.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: 03/27/2012 07:28 PM Subject:Re: [time-nuts] Distribution amp - Use a video amp unit ? Sent by:time-nuts-boun...@febo.com Bruce wrote: The above reverse isolation [~35 dB] is about 25dB lower than I would expect. D'oh! Bruce is right -- I calculated the reverse isolation incorrectly. I had only been expecting 40 dB, so I didn't question the result. The breadboard actually measured nearly 63 dB. Stable operation at unity gain is necessary if a feedback capacitor is used. The Miller capacitance of the output transistors sees to that (with an even greater phase margin when a faster transistor is used for Q1). An LM329 has similar noise without the dissipation of the internal heater in the LM399 I know. I just particularly like the 399, and have a pile of them. I rationalize using it in this case by noting that the range of frequencies where phase noise of the DA is important includes sub- to low-Hz frequencies at which thermal effects could make the unheated 329 significantly noisier (though if you keep drafts off both of them, it might not be by a large amount). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. inline: graycol.gif___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
cfo wrote: On Mon, 26 Mar 2012 08:11:16 +1300, Bruce Griffiths wrote: Bruce Griffiths wrote: A circuit schematic for a current feedback triple with reasonably low noise and distortion is attached. Bruce Thanx Bruce I'm an analog noob , so i have some questions. If i multiply that schematic by 8 , could i then just add the Tbolt input at all V1's ? The input capacitance may be a little high, however one could approximately compensate for it in a narrow band application. Should R15 + C11 + C12 also be multiplied ? One RC decoupling circuit like this for each amplifier is advisable to reduce crosstalk. Is V2 a 12v supply (i suppose so) ? Yes the schematic was taken from an LTSpice simulation. Could i replace the 2N3904 with BC850LT1 (smd) , and the 2N3906 with BC856ALT1 (smd) , else i have some BC337/BC327 - TO92 (non smd) No, the input and output capacitances of those transistors are probably a little too high. Would one chan work on a perf-board with wires (proof of concept) , or would it be to RF sensitive ? Its usually better to construct it over a ground plane rats nest style. A piece of unetched PCB works well. regards CFO Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
On 3/25/2012 9:54 PM, gary wrote: MMBD914 !=1n914. 1n914BWTm i.e. using a suffix, is something I haven't seen before, but technically 1N914BWT != 1n914. That is, in the strict sense, the 1n914 has to be a diode in that glass package. As long as we're being pedantic, you're wrong. What you say is only true if it is a JEDEC 1n914 that you're talking about. 1n914 cannot be trademarked or copyrighted. A manufacturer is perfectly free to make a device in a non-glass package and call it a 1n914, which means it _is_ a 1n914, as long as they stay away from JEDEC. Then again, following your lead in being impractically, completely, worthlessly pedantic, it's a JEDEC 1N914, not a 1n914. In the strict sense, the latter cannot exist under JEDEC. No one cares is probably an understatement. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Well, *I* care... (Damn, can't even keep a straight face hidden behind email) Ok, well at least it's an amusing argument. Well, partially. So, here's something I've wondered for a while: how are glass cased diodes made? Wouldn't the temperatures needed to form the glass and seal it to the leads destroy the silicon junction being put inside? Peter On 03/26/12, Mike Smi...@flatsurface.com wrote: On 3/25/2012 9:54 PM, gary wrote: MMBD914 !=1n914. 1n914BWTm i.e. using a suffix, is something I haven't seen before, but technically 1N914BWT != 1n914. That is, in the strict sense, the 1n914 has to be a diode in that glass package. As long as we're being pedantic, you're wrong. What you say is only true if it is a JEDEC 1n914 that you're talking about. 1n914 cannot be trademarked or copyrighted. A manufacturer is perfectly free to make a device in a non-glass package and call it a 1n914, which means it _is_ a 1n914, as long as they stay away from JEDEC. Then again, following your lead in being impractically, completely, worthlessly pedantic, it's a JEDEC 1N914, not a 1n914. In the strict sense, the latter cannot exist under JEDEC. No one cares is probably an understatement. ___ time-nuts mailing list -- [1]time-nuts@febo.com To unsubscribe, go to [2]https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. References 1. mailto:time-nuts@febo.com 2. https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
An Si junction can tolerate pretty high temperatures for a short while, or even a long while - Bob Pease reported having had a component sat on the hot end of a soldering iron for about 24 hours and still working afterwards ... I've never seen a description of how they make those glass cased parts - I guess speed is important. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter Gottlieb Sent: 26 March 2012 13:50 To: time-nuts@febo.com Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? how are glass cased diodes made? Wouldn't the temperatures needed to form the glass and seal it to the leads destroy the silicon junction being put inside? Peter ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I was only kidding a bit, since for a lot of the most common JEDEC and also non-JEDEC conventional (as opposed to SMD) discrete components they are similar parts with a similar numbering in SMD, and the 1N914 is one of them - so I found it not the best example :) . However, the same argument could be applied to the MMBT3904... in the same sense, != 2N3904 since in the strict sense it is not TO-92. Anyway I was not intending to generate any deep discussion about this matter :) Regards, Javier El 26/03/2012 03:54, gary escribió: MMBD914 !=1n914. 1n914BWTm i.e. using a suffix, is something I haven't seen before, but technically 1N914BWT != 1n914. That is, in the strict sense, the 1n914 has to be a diode in that glass package. On 3/25/2012 5:48 PM, Javier Herrero wrote: El 26/03/2012 02:35, gary escribió: I forgot to mention that those old jedec part numbers specify a package and electrical limit under one part number. That is, you can't find say a 1n914 in SMD, but you can find direct equivalents with other numbers. You will find supply houses listing SMD versions of jedec parts, but technically that is not correct. Oh, you can :) MMBD914 (SOT-23), 1N914BWT /SOD-523F) and some more. Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Si juctions are formed at temps of 1000C or more. Thermal failure is more likely to be due to alloying of metal contact areas. I used to lifetest transistors up to 360C for 20 hours with power applied!! and anything up to 6 months at 200C. You cant get those temps with plastic encalsulations though glass (double dummet) diodes will stand 300C easily Alan G3NYK --- On Mon, 26/3/12, David C. Partridge david.partri...@perdrix.co.uk wrote: From: David C. Partridge david.partri...@perdrix.co.uk Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Date: Monday, 26 March, 2012, 14:02 An Si junction can tolerate pretty high temperatures for a short while, or even a long while - Bob Pease reported having had a component sat on the hot end of a soldering iron for about 24 hours and still working afterwards ... I've never seen a description of how they make those glass cased parts - I guess speed is important. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter Gottlieb Sent: 26 March 2012 13:50 To: time-nuts@febo.com Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? how are glass cased diodes made? Wouldn't the temperatures needed to form the glass and seal it to the leads destroy the silicon junction being put inside? Peter ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Yes, but The glass used to make the body of the diode melts at something like 1500C! -Chuck Harris ALAN MELIA wrote: Si juctions are formed at temps of 1000C or more. Thermal failure is more likely to be due to alloying of metal contact areas. I used to lifetest transistors up to 360C for 20 hours with power applied!! and anything up to 6 months at 200C. You cant get those temps with plastic encalsulations though glass (double dummet) diodes will stand 300C easily Alan G3NYK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
On 3/26/2012 10:10 AM, Chuck Harris wrote: The glass used to make the body of the diode melts at something like 1500C! I think they're sintered, not melted, and it's more like 700 C - http://www.us.schott.com/epackaging/english/glass/technical_powder/passivation.html# ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Bruce wrote: A circuit schematic for a current feedback triple with reasonably low noise and distortion is attached. Quite a good performer for such a simple circuit. I found, both in modeling and on the bench, that there is the usual noise bump at 200-300 MHz and non-monotonic behavior out in the 900 MHz region. The latter can be solved by using an MPSH10 for Q1, which also brings the in-band noise and phase noise down a little. The former can be addressed by adding 8-10 pF across R2, at the expense of lowering the 3 dB point from around 150 MHz to around 80 MHz. For use as a 5 or 10 MHz distribution amp, I'd include the cap. The input impedance stays decently high everywhere the amp has useful gain -- there should be no problem paralleling 10 of them on a 50 ohm source. You can raise R2 just a tad to get back to unity gain, if needed. The reverse isolation is about 35 dB. This can be improved to around 50 dB by adding an emitter follower at the input, adjusting R7 and R8 to maintain Q1's base voltage. The noise increase is negligible. It is fairly sensitive to power supply noise, so you want a nice quiet supply. I used a regulator built with an LM399 and LT1028. Since the transformer is 1:1, one might be tempted to omit it. For a distribution amp that will be connected to a number of different instruments, however, one is well advised to include it to isolate the various returns. 6 bifilar turns on a T43-37 toroid core and 14 bifilar turns on a T61-37 both worked fine for me. If you have 1:1 transformers from a spare Ethernet card, those should, too. For a QD distribution amp, this would be a pretty good candidate. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Sintered means that the envelope is formed while the glass is in a powdered form, and is then melted to fuse it into glass. The key is they are using a very low temperature glass. For the Dumet seals on the wires (the pink band) to work, the copper in the seal has to be thoroughly wetted by the glass, which means it has to be at the glass melting temperature... and the part has to be cooled slowly to prevent it from shattering... which means it stays hot for a pretty long time. Interesting that the pre ROHS diodes were in a lead glass that could contain as much as 50% lead. The temperatures were higher than the current zinc glass formulations. -Chuck Harris Mike S wrote: On 3/26/2012 10:10 AM, Chuck Harris wrote: The glass used to make the body of the diode melts at something like 1500C! I think they're sintered, not melted, and it's more like 700 C - http://www.us.schott.com/epackaging/english/glass/technical_powder/passivation.html# ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
It would be interesting if the FTS-1050A curves were also plotted. Joe From: John Ackermann N8UR j...@febo.com To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: 03/25/2012 03:54 PM Subject:Re: [time-nuts] Distribution amp - Use a video amp unit ? Sent by:time-nuts-boun...@febo.com I haven't measured the video amps, but here are plots of an HP 5087A, TADD-1, and Spectracom 8140 tap unit for a baseline: http://febo.com/pages/amplifier_phase_noise/ John Tom Knox said the following on 03/25/2012 03:48 PM: Has anyone measured Phase Noise on any of these distribution amps? By looking at how widely the PN specs vary on the application specific Symmetricom and HP DA's it would be interesting to see how well these video da's perform in comparison. Thomas Knox Date: Sun, 25 Mar 2012 12:28:56 -0700 From: p...@petelancashire.com To: time-nuts@febo.com Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? Sounds like Paul and I have similar DA's or will soon when a Leitch gets to the front porch next week. Its bandwidth is spec'd at 30 MHz. The only question I have on using DA's is the effect of them being designed to work in a 75 ohm environment. One thing to watch out for is what cards they have in them. -pete On Sun, Mar 25, 2012 at 11:39 AM, paul swedpaulsw...@gmail.com wrote: Well the easy answer. The older 1984 video amps would roll off above 6 MC or so. However as the IC technology took over they easily could do 30 Mhz. I have used Grass valley 8500 series for at least 10-15 years and the work very well. I also have sets of Leitch DAs that are fine. Picked up the whole tray for some silly amount of $ 20 I think. I prefer the simple 8601 DAs but have 8604 delay days and they can all be made into simple DAs with a few jumpers that are on the boards. I have also used a rgb da 6 output for each channel. No issue at all. One comment you would want to insure the amps are ac coupled and clamping turned off since there is no sync signal to establish the clamp level. Regards Paul WB8TSL On Sun, Mar 25, 2012 at 2:14 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: cfo wrote: I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%**20files/rubidium.pdf http://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Winding your own transformers isnt particularly difficult if you have suitable (binocular) cores. The discrete amplifier shown has a class AB output stage, lower distortion is possible if a class A output stage is used (requires an extra resistor between the output stage emitters and an additional diode in series with the LED). With a Class A output stage the 39 ohm resistors should be replaced by a a pair of 100 ohm resistors to match the load. Significantly lower distortion is possible if feedback from the output to the input stage is used. If the feedback gain is unity (or less) at dc higher AC gains won't significantly degrade the close in phase noise. A different amplifier topology using the same number of transistors will allow a higher reverse isolation to be achieved. One problem with video distribution units (aside from the relatively high phase noise floor) is the limited output drive available. For some purposes 16-20dBm outputs are desirable. Bruce __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nuts https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions
Re: [time-nuts] Distribution amp - Use a video amp unit ?
On 3/26/2012 8:15 AM, Charles P. Steinmetz wrote: Bruce wrote: A circuit schematic for a current feedback triple with reasonably low noise and distortion is attached. Quite a good performer for such a simple circuit. I found, both in modeling and on the bench, that there is the usual noise bump at 200-300 MHz and non-monotonic behavior out in the 900 MHz region. The latter can be solved by using an MPSH10 for Q1, which also brings the in-band noise and phase noise down a little. The former can be addressed by adding 8-10 pF across R2, at the expense of lowering the 3 dB point from around 150 MHz to around 80 MHz. For use as a 5 or 10 MHz distribution amp, I'd include the cap. The input impedance stays decently high everywhere the amp has useful gain -- there should be no problem paralleling 10 of them on a 50 ohm source. You can raise R2 just a tad to get back to unity gain, if needed. The reverse isolation is about 35 dB. This can be improved to around 50 dB by adding an emitter follower at the input, adjusting R7 and R8 to maintain Q1's base voltage. The noise increase is negligible. It is fairly sensitive to power supply noise, so you want a nice quiet supply. I used a regulator built with an LM399 and LT1028. Since the transformer is 1:1, one might be tempted to omit it. For a distribution amp that will be connected to a number of different instruments, however, one is well advised to include it to isolate the various returns. 6 bifilar turns on a T43-37 toroid core and 14 bifilar turns on a T61-37 both worked fine for me. If you have 1:1 transformers from a spare Ethernet card, those should, too. For a QD distribution amp, this would be a pretty good candidate. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. if one is distributing 10 Mhz, does it really matter what the circuit does at 300 and 900 Mhz?? 73's, Randy, KI6WAS ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I dont think so, pure quartz melts at, I think, 1440C but glasses (like lead-glass) melt at much lower temperatures 500 to 600C. Remember the chemical glass-blowing skill of the technicians. The glass mix has to be formulated to match the expansion rate of the lead seals. A iron alloy with a small expansion coeff. whose name I dont recall was used for the leads. Glasses soften well below melting temperature (I remember sucked in 807 and 6146 tubes that had dissipated a few watts to many) Then the softened glass is rolled onto the lead. If you look carefully at some glass wire-ended diodes you will see a slight waist where this happened. The seal and adhesion is a thin metal/oxide/glass interface. Soldering temps rarely cause trouble but bending the lead wire close to the glass should be avoided. I used an oxy-hydrogen flame micro-welder for making connections for high temp life tests, so the wires got quite hot, but not close to the metal-glass seal. I only had peripheral knowledge of glass technology but most of the technology was developed in the lamp and valve (tube ) industries. I guess there are great references in the web now :-)) Alan G3NYK --- On Mon, 26/3/12, Chuck Harris cfhar...@erols.com wrote: From: Chuck Harris cfhar...@erols.com Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? To: Discussion of precise time and frequency measurement time-nuts@febo.com Date: Monday, 26 March, 2012, 15:10 Yes, but The glass used to make the body of the diode melts at something like 1500C! -Chuck Harris ALAN MELIA wrote: Si juctions are formed at temps of 1000C or more. Thermal failure is more likely to be due to alloying of metal contact areas. I used to lifetest transistors up to 360C for 20 hours with power applied!! and anything up to 6 months at 200C. You cant get those temps with plastic encalsulations though glass (double dummet) diodes will stand 300C easily Alan G3NYK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Pure quartz glass, which is silicon dioxide, softens (bends) at 1665C, and melts at something around 2000C. Softening and melting are not the same thing. At the softening point glass can be bent without breaking, at the melting point (which is quite wide) it flows like a liquid. It has to get above the flow point to be able to adhere to the Dumet seals on the wire. Soda lime glass melts at about 1500C, as I said, but it bends at about 900C. The highly leaded glasses that they used to use to make glass diodes melt at about 700C, and the highly zinced glasses that they currently use melt at about 560C. I have made metal-glass vacuum seals, and they are done at the liquid point of the glass. At that point, the glass flows and sticks to itself, and just about everything. It is the same temperature used to weld two pieces of like glass to each other. At the bending point, however, glass won't stick to other glass. -Chuck Harris ALAN MELIA wrote: I dont think so, pure quartz melts at, I think, 1440C but glasses (like lead-glass) melt at much lower temperatures 500 to 600C. Remember the chemical glass-blowing skill of the technicians. The glass mix has to be formulated to match the expansion rate of the lead seals. A iron alloy with a small expansion coeff. whose name I dont recall was used for the leads. Glasses soften well below melting temperature (I remember sucked in 807 and 6146 tubes that had dissipated a few watts to many) Then the softened glass is rolled onto the lead. If you look carefully at some glass wire-ended diodes you will see a slight waist where this happened. The seal and adhesion is a thin metal/oxide/glass interface. Soldering temps rarely cause trouble but bending the lead wire close to the glass should be avoided. I used an oxy-hydrogen flame micro-welder for making connections for high temp life tests, so the wires got quite hot, but not close to the metal-glass seal. I only had peripheral knowledge of glass technology but most of the technology was developed in the lamp and valve (tube ) industries. I guess there are great references in the web now :-)) Alan G3NYK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Randy wrote: if one is distributing 10 Mhz, does it really matter what the circuit does at 300 and 900 Mhz?? That depends on what it is feeding and what noise and other signals are getting to the DA input. Some synthesized 10 MHz sources produce energy well above 10 MHz. I consider nonmonotonic behavior to be a design flaw in general (except where it is specifically desired or you are up against the bleeding edge of technology and it can't be avoided), so I eliminate it at every opportunity as long as the fix doesn't cause worse problems. In this case, the nonmonotonicity is cured by replacing an 8¢ transistor with a 16¢ transistor, and some other small benefits are realized at the same time, so I say it's 8¢ well spent. Nearly a whole dollar extra for a 12-output DA. The noise bump is cured by restricting the 3 dB bandwidth to ~80 MHz, which does not affect the 10 MHz but may help the receiving instrument if it is sensitive to VHF noise (although the magnitude of the bump is not large). I consider these good prophylactic design measures. Practicing them keeps you out of trouble that you might not even know was threatening, whether or not it makes a practical difference WRT a particular design. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I have often seen (don't ask me how) silicon diodes getting so hot that they unsolder themselves from the board and fall at the bottom of the equipment enclosure, yet they work fine after the fact even though they don't look so good. I have been tempted to solder them back in in more than one occasion... I have not had it happen with an smd part yet, but its just a matter of time. Didier KO4BB Sent from my BlackBerry Wireless thingy while I do other things... -Original Message- From: ALAN MELIA alan.me...@btinternet.com Sender: time-nuts-boun...@febo.com Date: Mon, 26 Mar 2012 14:27:39 To: Discussion of precise time and frequency measurementtime-nuts@febo.com Reply-To: Discussion of precise time and frequency measurement time-nuts@febo.com Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? Si juctions are formed at temps of 1000C or more. Thermal failure is more likely to be due to alloying of metal contact areas. I used to lifetest transistors up to 360C for 20 hours with power applied!! and anything up to 6 months at 200C. You cant get those temps with plastic encalsulations though glass (double dummet) diodes will stand 300C easily Alan G3NYK --- On Mon, 26/3/12, David C. Partridge david.partri...@perdrix.co.uk wrote: From: David C. Partridge david.partri...@perdrix.co.uk Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? To: 'Discussion of precise time and frequency measurement' time-nuts@febo.com Date: Monday, 26 March, 2012, 14:02 An Si junction can tolerate pretty high temperatures for a short while, or even a long while - Bob Pease reported having had a component sat on the hot end of a soldering iron for about 24 hours and still working afterwards ... I've never seen a description of how they make those glass cased parts - I guess speed is important. Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter Gottlieb Sent: 26 March 2012 13:50 To: time-nuts@febo.com Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? how are glass cased diodes made? Wouldn't the temperatures needed to form the glass and seal it to the leads destroy the silicon junction being put inside? Peter ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Charles P. Steinmetz wrote: Bruce wrote: A circuit schematic for a current feedback triple with reasonably low noise and distortion is attached. Quite a good performer for such a simple circuit. I found, both in modeling and on the bench, that there is the usual noise bump at 200-300 MHz and non-monotonic behavior out in the 900 MHz region. The latter can be solved by using an MPSH10 for Q1, which also brings the in-band noise and phase noise down a little. The former can be addressed by adding 8-10 pF across R2, at the expense of lowering the 3 dB point from around 150 MHz to around 80 MHz. For use as a 5 or 10 MHz distribution amp, I'd include the cap. The stability of Sziklai pair like configurations (in this case a triple) is enhanced if the input device has a significantly higher ft than the output device(s). Stable operation at unity gain is necessary if a feedback capacitor is used. The input impedance stays decently high everywhere the amp has useful gain -- there should be no problem paralleling 10 of them on a 50 ohm source. You can raise R2 just a tad to get back to unity gain, if needed. The reverse isolation is about 35 dB. This can be improved to around 50 dB by adding an emitter follower at the input, adjusting R7 and R8 to maintain Q1's base voltage. The noise increase is negligible. The above reverse isolation is about 25dB lower than I would expect. The impedance of the power supply rail at the test frequency should be low so using bypass caps with low inductance and esr is desirable. The reverse isolation of an emitter follower is determined by the current gain at the test frequency. Thus with an ft of 300MHz it should be around 30dB at 10MHz. It is fairly sensitive to power supply noise, so you want a nice quiet supply. I used a regulator built with an LM399 and LT1028. An LM329 has similar noise without the dissipation of the internal heater in the LM399. The 10nF cap between the output transistor bases is the primary source of this sensistivity. Since the transformer is 1:1, one might be tempted to omit it. For a distribution amp that will be connected to a number of different instruments, however, one is well advised to include it to isolate the various returns. 6 bifilar turns on a T43-37 toroid core and 14 bifilar turns on a T61-37 both worked fine for me. If you have 1:1 transformers from a spare Ethernet card, those should, too. For a QD distribution amp, this would be a pretty good candidate. Best regards, Charles Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Distribution amp - Use a video amp unit ?
I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I think people have used video amps. I got one recently for nearly zero cost and it works as spec'd but video signals are typically 1 volt peak to peak and the amp is spec'd for 10MHz, 1dB which means I'm right at the limit and I'm a 1 dB down, just as the spec says. Is 1V P-P enough for your equipment? This amp is easy to modify and I can greatly improve the specs by running it at +/- 15V rather then the +/-5V it now uses. So, my opinion: Video distribution amps can work but you'll be right on the edge of the spec'd limits all around. On Sun, Mar 25, 2012 at 9:26 AM, cfo xne...@luna.kyed.com wrote: I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Chris, that's got to be a really old video distribution amplifier. I was just given a thin rack-mount video distribution amplifier with ten outputs and the specification says 300 MHz bandwidth at 3 dB. I have not measured its output level. It is made by Kramer and has BNC and S-video in/out but no RCA composite video connectors. Well, that's the published spec; I have not tested it on my Tek 2712. We are not talking about critical phase relationships, just distributing 10 MHz for sig generators and counters. Larry On 3/25/2012 11:01 AM, Chris Albertson wrote: I think people have used video amps. I got one recently for nearly zero cost and it works as spec'd but video signals are typically 1 volt peak to peak and the amp is spec'd for 10MHz, 1dB which means I'm right at the limit and I'm a 1 dB down, just as the spec says. Is 1V P-P enough for your equipment? This amp is easy to modify and I can greatly improve the specs by running it at +/- 15V rather then the +/-5V it now uses. So, my opinion: Video distribution amps can work but you'll be right on the edge of the spec'd limits all around. ... -- Best wishes, Larry McDavid W6FUB Anaheim, CA (20 miles southeast of Los Angeles, near Disneyland) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
cfo wrote: I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Winding your own transformers isnt particularly difficult if you have suitable (binocular) cores. The discrete amplifier shown has a class AB output stage, lower distortion is possible if a class A output stage is used (requires an extra resistor between the output stage emitters and an additional diode in series with the LED). With a Class A output stage the 39 ohm resistors should be replaced by a a pair of 100 ohm resistors to match the load. Significantly lower distortion is possible if feedback from the output to the input stage is used. If the feedback gain is unity (or less) at dc higher AC gains won't significantly degrade the close in phase noise. A different amplifier topology using the same number of transistors will allow a higher reverse isolation to be achieved. One problem with video distribution units (aside from the relatively high phase noise floor) is the limited output drive available. For some purposes 16-20dBm outputs are desirable. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Well the easy answer. The older 1984 video amps would roll off above 6 MC or so. However as the IC technology took over they easily could do 30 Mhz. I have used Grass valley 8500 series for at least 10-15 years and the work very well. I also have sets of Leitch DAs that are fine. Picked up the whole tray for some silly amount of $ 20 I think. I prefer the simple 8601 DAs but have 8604 delay days and they can all be made into simple DAs with a few jumpers that are on the boards. I have also used a rgb da 6 output for each channel. No issue at all. One comment you would want to insure the amps are ac coupled and clamping turned off since there is no sync signal to establish the clamp level. Regards Paul WB8TSL On Sun, Mar 25, 2012 at 2:14 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: cfo wrote: I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%**20files/rubidium.pdfhttp://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Winding your own transformers isnt particularly difficult if you have suitable (binocular) cores. The discrete amplifier shown has a class AB output stage, lower distortion is possible if a class A output stage is used (requires an extra resistor between the output stage emitters and an additional diode in series with the LED). With a Class A output stage the 39 ohm resistors should be replaced by a a pair of 100 ohm resistors to match the load. Significantly lower distortion is possible if feedback from the output to the input stage is used. If the feedback gain is unity (or less) at dc higher AC gains won't significantly degrade the close in phase noise. A different amplifier topology using the same number of transistors will allow a higher reverse isolation to be achieved. One problem with video distribution units (aside from the relatively high phase noise floor) is the limited output drive available. For some purposes 16-20dBm outputs are desirable. Bruce __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Sounds like Paul and I have similar DA's or will soon when a Leitch gets to the front porch next week. Its bandwidth is spec'd at 30 MHz. The only question I have on using DA's is the effect of them being designed to work in a 75 ohm environment. One thing to watch out for is what cards they have in them. -pete On Sun, Mar 25, 2012 at 11:39 AM, paul swed paulsw...@gmail.com wrote: Well the easy answer. The older 1984 video amps would roll off above 6 MC or so. However as the IC technology took over they easily could do 30 Mhz. I have used Grass valley 8500 series for at least 10-15 years and the work very well. I also have sets of Leitch DAs that are fine. Picked up the whole tray for some silly amount of $ 20 I think. I prefer the simple 8601 DAs but have 8604 delay days and they can all be made into simple DAs with a few jumpers that are on the boards. I have also used a rgb da 6 output for each channel. No issue at all. One comment you would want to insure the amps are ac coupled and clamping turned off since there is no sync signal to establish the clamp level. Regards Paul WB8TSL On Sun, Mar 25, 2012 at 2:14 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: cfo wrote: I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%**20files/rubidium.pdfhttp://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Winding your own transformers isnt particularly difficult if you have suitable (binocular) cores. The discrete amplifier shown has a class AB output stage, lower distortion is possible if a class A output stage is used (requires an extra resistor between the output stage emitters and an additional diode in series with the LED). With a Class A output stage the 39 ohm resistors should be replaced by a a pair of 100 ohm resistors to match the load. Significantly lower distortion is possible if feedback from the output to the input stage is used. If the feedback gain is unity (or less) at dc higher AC gains won't significantly degrade the close in phase noise. A different amplifier topology using the same number of transistors will allow a higher reverse isolation to be achieved. One problem with video distribution units (aside from the relatively high phase noise floor) is the limited output drive available. For some purposes 16-20dBm outputs are desirable. Bruce __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Has anyone measured Phase Noise on any of these distribution amps? By looking at how widely the PN specs vary on the application specific Symmetricom and HP DA's it would be interesting to see how well these video da's perform in comparison. Thomas Knox Date: Sun, 25 Mar 2012 12:28:56 -0700 From: p...@petelancashire.com To: time-nuts@febo.com Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? Sounds like Paul and I have similar DA's or will soon when a Leitch gets to the front porch next week. Its bandwidth is spec'd at 30 MHz. The only question I have on using DA's is the effect of them being designed to work in a 75 ohm environment. One thing to watch out for is what cards they have in them. -pete On Sun, Mar 25, 2012 at 11:39 AM, paul swed paulsw...@gmail.com wrote: Well the easy answer. The older 1984 video amps would roll off above 6 MC or so. However as the IC technology took over they easily could do 30 Mhz. I have used Grass valley 8500 series for at least 10-15 years and the work very well. I also have sets of Leitch DAs that are fine. Picked up the whole tray for some silly amount of $ 20 I think. I prefer the simple 8601 DAs but have 8604 delay days and they can all be made into simple DAs with a few jumpers that are on the boards. I have also used a rgb da 6 output for each channel. No issue at all. One comment you would want to insure the amps are ac coupled and clamping turned off since there is no sync signal to establish the clamp level. Regards Paul WB8TSL On Sun, Mar 25, 2012 at 2:14 PM, Bruce Griffiths bruce.griffi...@xtra.co.nz wrote: cfo wrote: I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%**20files/rubidium.pdfhttp://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Winding your own transformers isnt particularly difficult if you have suitable (binocular) cores. The discrete amplifier shown has a class AB output stage, lower distortion is possible if a class A output stage is used (requires an extra resistor between the output stage emitters and an additional diode in series with the LED). With a Class A output stage the 39 ohm resistors should be replaced by a a pair of 100 ohm resistors to match the load. Significantly lower distortion is possible if feedback from the output to the input stage is used. If the feedback gain is unity (or less) at dc higher AC gains won't significantly degrade the close in phase noise. A different amplifier topology using the same number of transistors will allow a higher reverse isolation to be achieved. One problem with video distribution units (aside from the relatively high phase noise floor) is the limited output drive available. For some purposes 16-20dBm outputs are desirable. Bruce __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
On Sun, Mar 25, 2012 at 12:28 PM, Pete Lancashire p...@petelancashire.com wrote: The only question I have on using DA's is the effect of them being designed to work in a 75 ohm environment. Swap out a few resistors and you can fix the above problem.unless they used those 75 ohm BNCs but those are rare and if you are a true nut you can replace them. In my amp the resistors are all very easy to swap through hole 1/4W types Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I haven't measured the video amps, but here are plots of an HP 5087A, TADD-1, and Spectracom 8140 tap unit for a baseline: http://febo.com/pages/amplifier_phase_noise/ John Tom Knox said the following on 03/25/2012 03:48 PM: Has anyone measured Phase Noise on any of these distribution amps? By looking at how widely the PN specs vary on the application specific Symmetricom and HP DA's it would be interesting to see how well these video da's perform in comparison. Thomas Knox Date: Sun, 25 Mar 2012 12:28:56 -0700 From: p...@petelancashire.com To: time-nuts@febo.com Subject: Re: [time-nuts] Distribution amp - Use a video amp unit ? Sounds like Paul and I have similar DA's or will soon when a Leitch gets to the front porch next week. Its bandwidth is spec'd at 30 MHz. The only question I have on using DA's is the effect of them being designed to work in a 75 ohm environment. One thing to watch out for is what cards they have in them. -pete On Sun, Mar 25, 2012 at 11:39 AM, paul swedpaulsw...@gmail.com wrote: Well the easy answer. The older 1984 video amps would roll off above 6 MC or so. However as the IC technology took over they easily could do 30 Mhz. I have used Grass valley 8500 series for at least 10-15 years and the work very well. I also have sets of Leitch DAs that are fine. Picked up the whole tray for some silly amount of $ 20 I think. I prefer the simple 8601 DAs but have 8604 delay days and they can all be made into simple DAs with a few jumpers that are on the boards. I have also used a rgb da 6 output for each channel. No issue at all. One comment you would want to insure the amps are ac coupled and clamping turned off since there is no sync signal to establish the clamp level. Regards Paul WB8TSL On Sun, Mar 25, 2012 at 2:14 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: cfo wrote: I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%**20files/rubidium.pdfhttp://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. Winding your own transformers isnt particularly difficult if you have suitable (binocular) cores. The discrete amplifier shown has a class AB output stage, lower distortion is possible if a class A output stage is used (requires an extra resistor between the output stage emitters and an additional diode in series with the LED). With a Class A output stage the 39 ohm resistors should be replaced by a a pair of 100 ohm resistors to match the load. Significantly lower distortion is possible if feedback from the output to the input stage is used. If the feedback gain is unity (or less) at dc higher AC gains won't significantly degrade the close in phase noise. A different amplifier topology using the same number of transistors will allow a higher reverse isolation to be achieved. One problem with video distribution units (aside from the relatively high phase noise floor) is the limited output drive available. For some purposes 16-20dBm outputs are desirable. Bruce __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Bruce wrote: A circuit schematic for a current feedback triple with reasonably low noise and distortion is attached. One caution regarding the 100 uH inductor (L3) -- many inductors of this value exhibit self-resonance below 10 MHz, so some care may be necessary in selection. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I'm 99% sure that is all it is .. one thing nice about using something designed 20 yrs ago is it wont be a hybrid with the termination on the ceramic. :-) On Sun, Mar 25, 2012 at 12:51 PM, Chris Albertson albertson.ch...@gmail.com wrote: On Sun, Mar 25, 2012 at 12:28 PM, Pete Lancashire p...@petelancashire.com wrote: The only question I have on using DA's is the effect of them being designed to work in a 75 ohm environment. Swap out a few resistors and you can fix the above problem. unless they used those 75 ohm BNCs but those are rare and if you are a true nut you can replace them. In my amp the resistors are all very easy to swap through hole 1/4W types Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I need a distribution amp for my Tbolt , with 6..8+ outputs The TAPR-1 is NA , and the successor status is ???. I need it for distributing 10Mhz ref-clock to Counters (HP,Racal,Phillips), a Rigol Sig-gen maybe Oscilloscopes etc. It's for better than ocxo/hobby use , and not Tnut (ps accuracy). I have seen suggestions for using a video distributiution unit. But in my part of the world (EU) , there isn't a lot on eby. I have seen some RGB amps , and was wondering if i could use those ? Could i use a 1:6 RGB unit for : Tbolt on R , FEI-5680A on G - and ?? on B ? I'm not experienced (yet) in the analog domain. If i go (simple diy) Would this one work (also wo. the trafo's) ? http://www.oz9fw.dk/PDF%20files/rubidium.pdf I do have some trafo's on an old 10Mhz 8-chan Hub , that i might be able to salvage if needed. Thanx for any input/hints CFo - T-Nut beginner Denmark. I have a couple Extron ADA-3-80 RGB video distribution amps that I use for 10 MHz distribution, and they work well for me. I send my 10MHz standard to a number of bench instruments, which seem to be quite happy with it. They are 75 ohm units (for video); you can use them as-is or change the source resistors inside the unit to 50 ohms if you wish. Gain is switchable between 1:1 and 1:0.7. The gain is somewhat adjustable.internally. Noise is pretty low. They come up on ebay fairly frequently, and at reasonable prices. Didier (KO4BB) has a page describing his experience with the Extron unit at http://www.ko4bb.com/ham_radio/Extron_3_80/. Cheers, Dave M A woman has the last word in any argument. Anything a man says after that is the beginning of a new argument. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
On Mon, 26 Mar 2012 08:11:16 +1300, Bruce Griffiths wrote: Bruce Griffiths wrote: A circuit schematic for a current feedback triple with reasonably low noise and distortion is attached. Bruce Thanx Bruce I'm an analog noob , so i have some questions. If i multiply that schematic by 8 , could i then just add the Tbolt input at all V1's ? Should R15 + C11 + C12 also be multiplied ? Is V2 a 12v supply (i suppose so) ? Could i replace the 2N3904 with BC850LT1 (smd) , and the 2N3906 with BC856ALT1 (smd) , else i have some BC337/BC327 - TO92 (non smd) Would one chan work on a perf-board with wires (proof of concept) , or would it be to RF sensitive ? regards CFO ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Thats the RGB amps I have used the Extrons. Its in the basement and worked very well. Could not remember the name. On Sun, Mar 25, 2012 at 4:02 PM, cfo xne...@luna.dyndns.dk wrote: On Mon, 26 Mar 2012 08:11:16 +1300, Bruce Griffiths wrote: Bruce Griffiths wrote: A circuit schematic for a current feedback triple with reasonably low noise and distortion is attached. Bruce Thanx Bruce I'm an analog noob , so i have some questions. If i multiply that schematic by 8 , could i then just add the Tbolt input at all V1's ? Should R15 + C11 + C12 also be multiplied ? Is V2 a 12v supply (i suppose so) ? Could i replace the 2N3904 with BC850LT1 (smd) , and the 2N3906 with BC856ALT1 (smd) , else i have some BC337/BC327 - TO92 (non smd) Would one chan work on a perf-board with wires (proof of concept) , or would it be to RF sensitive ? regards CFO ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I'm not so sure about the circuit. The base drive on Q3 is more of less AC given that the resistor can only pull current out of the base. That is, I don't see a DC bias on Q3. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Gotcha. LEDs are hetero junction, yielding more than a diode drop. On 3/25/2012 5:05 PM, David wrote: On Sun, 25 Mar 2012 16:39:57 -0700, garyli...@lazygranch.com wrote: I'm not so sure about the circuit. The base drive on Q3 is more of less AC given that the resistor can only pull current out of the base. That is, I don't see a DC bias on Q3. R7, R8, and LED D2 sets the base voltage at about 1.8 volts through R4. Subtract Vbe and Q3's idle current will be about 36 milliamps set by 1.2 volts across the 33 ohm emitter resistor. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I forgot to mention that those old jedec part numbers specify a package and electrical limit under one part number. That is, you can't find say a 1n914 in SMD, but you can find direct equivalents with other numbers. You will find supply houses listing SMD versions of jedec parts, but technically that is not correct. Anyway, there are probably direct electrical versions of the 2n3904 and 2n3906. For example MMBT3904. I assume when ICs hit the market the idea of making the package be a suffix evolved rather than making the die and package be one specific number. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
El 26/03/2012 02:35, gary escribió: I forgot to mention that those old jedec part numbers specify a package and electrical limit under one part number. That is, you can't find say a 1n914 in SMD, but you can find direct equivalents with other numbers. You will find supply houses listing SMD versions of jedec parts, but technically that is not correct. Oh, you can :) MMBD914 (SOT-23), 1N914BWT /SOD-523F) and some more. Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
MMBD914 !=1n914. 1n914BWTm i.e. using a suffix, is something I haven't seen before, but technically 1N914BWT != 1n914. That is, in the strict sense, the 1n914 has to be a diode in that glass package. On 3/25/2012 5:48 PM, Javier Herrero wrote: El 26/03/2012 02:35, gary escribió: I forgot to mention that those old jedec part numbers specify a package and electrical limit under one part number. That is, you can't find say a 1n914 in SMD, but you can find direct equivalents with other numbers. You will find supply houses listing SMD versions of jedec parts, but technically that is not correct. Oh, you can :) MMBD914 (SOT-23), 1N914BWT /SOD-523F) and some more. Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
Charles P. Steinmetz wrote: Bruce wrote: A circuit schematic for a current feedback triple with reasonably low noise and distortion is attached. One caution regarding the 100 uH inductor (L3) -- many inductors of this value exhibit self-resonance below 10 MHz, so some care may be necessary in selection. Best regards, Charles EPCOS produce a suitable inductor with its first SRF around 20Mhz or so. The inductor may be omitted if noise and loop gain isnt too critical. Bruce ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
