[time-nuts] Positioning Accuracy - Lady Heather vs. T-Bolt Monitor
Hello Time Nuts -My question is --- both LH and T-Bolt Mon will readout position during andat the conclusion of a self survey.The readout from LH provides 2 additional digits of resolution compared to T-bolt Monitor.That is LH provides 7 digits of Lat or Lon to the right of the decimal point; T-bolt Mon provides 5.Now with the understanding that one needs to set a relatively high elevation andamplitude masks to eliminate all but robust signals, and that one must take a lotof samples (48,000 or more) --- Has anyone verified the utility of those extra two digits?By utility I mean - is the 6th decimal place accurate assuming the above constraints.I am trying to nail a position in Longitude to 2 feet or less at a Latitude of 38 degrees N.I have lots of time to take lots of survey points so that is not an issue.Best regards - John k6iql ___ 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] Suggested Low Noise Transistors
I offer the following for your consideration. Once upon a time - about 1968 Motorola introduced 4 low noise transistors for audio and low frequency applications. There were th 2N5086, 5087, 5088 and 5089. The 5086 and 5087 are PNP and the 5088 and 5089 are NPN. They are almost perfect complements to each other. They are still made though the part numbers are now MMBT2N5088L and so on. As of September 2014 I bought and used several of them in a photo transistor preamp for a laser theodolite receiver. They are commonly available from distributor stock. They differ slightly in noise figure and Beta. Since 1970 I have used them in a number of professional applications from DC up to 50 MHz. The latter a 6 channel summing amplifier for a military mapping photo transistor device. These are some of the hottest bi-polar devices known with a specified minimum beta of 150 at 100 uA. The beta is pretty flat up to 10 mA. The current gain bandwidth product varies from a bit less than 50 at 100 uA up to 500 at 10 mA. At 1 mA it is 200. The low frequency noise figure IS specified - 2N5086 3.0 dB MAX (Ic = 20 uA, Vce = 5 v, Rs = 10 K, from 10 Hz to 15.7 kHz) 2N5087 2.0 dB Max, 1.0 dB typical(Ic = 100 uA, Vce = 5V, Rs = 3K, f = 1.0 kHz) Data is provided for the effect of source resistance and Ic on the noise figure. Data for the complementary 2N5088 and 2N5089 is nearly identical. You can look it up. It is all on the data sheet for the original devices and may be found in the "Semiconductor Data Handbook" issued my Motorola in the 1970. the data may also be on the "ON" semiconductor web site among other places. With their relatively low high frequency response (as compared to a 2n2857) you are not risking oscillations up in the the microwave bands where most of you do not have the test gear to find and fix any funny business. This is a really nice calm set of devices and easy to use. I believe that when I bought them last year they were around a buck each. The 5086 and 5087 are PNP and the 5088 and 5089 are NPN. They are still made though the part numbers are now MMBT2N5088L and so on. As of September 2014 I bought and used several of them in a photo transistor preamp for a laser theodolite receiver. They are commonly available from distributor stock. I have not applied them in low noise oscillator applications and have no idea as to their suitability for that. But they are one hell of a transistor family and worth knowing about. Best regards john c roos K6iql spring hill ks ___ 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] T.I. questions (Magnus Danielson)
A further comment on design of pseudo random code generators. At some point the code may enter the dreaded all "zeros" state. This clocks a zero on the input stage through all stages and the whole thing just stops. So a AND gate looking at all stages in parallel is used to detect the all zero state and get things going again. One way is to XOR the output of the AND and the input to any stage. since the all zero state is not permitted the length of the code is can be no longer than the well known 2^n -1 bits. Also if the number of codes desired is limited - some of the FFs may be replace by a delay line. Using MECL III and a delay line a 350 MHz rather long code generator was implemented in my lab with only few JK FFs. That was in about 1979. For more info see Dixon "Spread Spectrum Systems". john roos k6iql ___ 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] Hp Family GPS DOs vs. Tbolts Rev 3 SW and Trimble VCXO
With all of the discussion of the recent availability of various HP family GPS DO devices, I was wondering if I should get a couple. Presently I have a couple of T-bolts that seem to serve me well. What wold be the advantages gained by going to the HPs. Need 10 MHz output though. Any thoughts? -73 john roos k6iql ___ 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] 5 to 10 MHz Quad Driven Mixer doubler article
Apparently there is some interest in this technique. So far I have 35 requests and still counting. Please if you do want a copy send me an email OFF LIST to johncr...@aol.com. Requests posted on list are too hard to find and too hard to make into a master address list. In addition to the basic article I will add some related material. And as they say on TV "thats not all". One QEX reader asked how it compares with the classic push-push doubler. I prepared a brief paper on the push-push doubler and will include it as well. They are both useful depending upon the host application. For one thing the push-push circuit can give healthy power gain and power output up to a Watt or more. I plan to fire off the package on Sunday. Best regards to all - john c roos k6iql ___ 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] 5 to 10 MHz Quadrature Driven Mixer Doubler
I have received permission to distribute copies of my QEX article on this subject from ARRL. In addition to the article I will include full size schematics and color photos of the various assemblies. The design includes an adjustable 10 MHz output amplifier for driving 50 OHM loads. If interested please email me off list at johncr...@aol.com I will wait a few days and then mail a complete package to all requestors. Best regards to all - 73 john k6iql ___ 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.
