Daniel,

I need your mailing address! I'm not licensed so I can't look up your address on the call lists. I hope to correct that soon, but am too busy playing with other toys.

I intend to send a pair of tinySAs and a nanoVNA as they are so versatile. There is also the possibility of designing useful accessories such as filters for using the tinySA as a signal generator. A 5th order Cauer is very effective if designed carefully. Please send me your lab inventory so I have a better idea of what should be most useful to you. I've sent nanoVNAs to other people in the UK and EU as a "Thank You" for having designed useful OSHW/OSSW kit that I use. So I should be able to order from China for delivery to Argentina without too much trouble.

A bit of personal history. I "retired" at 54 in 2007 to move to Arkansas from Houston. The move took 7 months and 3 28' tractor trailer loads. I disposed of one trailer load of stuff in Houston.
Dad's health was failing and as the eldest child as well as the closest it was my duty. I also wanted very much to get away from Houston because of the crime and hurricanes.

I sold my house for $500 below asking price on 23 June 2008 a few weeks before the credit markets froze and Ike hit Houston. The area in which I lived was without power for 3 weeks. Houston summer without AC is very grim.

I had worked as a contract research scientist/programmer since 1992 and was well known in the oil industry having missed 3 annual Society of Exploration Geophysicists meetings in 28 years. I was absolutely confident I'd get work once I was unpacked. I have a 5000+ volume technical library, computers, etc. Plan was to spend 1 week a month in Houston and do the rest of the work from Arkansas. But alas it was not to be. I deeply miss the the social aspect of working and have suffered from severe depression from the technical social isolation in a village of 7000 where the ham radio club doesn't even discuss radio at their meetings.

There is also a personal visceral component. Dad's big passion was radio, but he also had a lathe, mill and woodshop all fully stocked with parts organized in labeled bins. At age 42 his employer moved us from NYC to Bluefield, West Virginia (Dad was selling coal processing equipment) and then 2 years later decided to move us again. Dad quit and we moved to Arkansas to speculate on real estate and operate a restaurant. Dad lived another 49 years, but never had anything better than a bit of space with a very disorganized portion of his shop equipment available. Before the moves he was building 5-6 radios and T&M projects a year or more judging from the detritus he left. So between my frustrations with lack of proper T&M kit and realizing what happened to Dad, designing low cost electronic T&M kit is an all consuming passion for me. However, Dad left me almost 1000 sq meters of stuff in several commercial buildings a meter or so deep with which I have been grappling for 15 years. I'm finally getting close to the end. I've boxed up an initial shipment of vacuum tubes to a dealer. After the 1200-1500 tubes are gone I will start on the passive components, sorting and inventorying them to sell to a dealer.

When Tom Oldbury (tom66) contacted me via EEVblog asking for DSP assistance with his DSO project I was delighted and we had a lot of fun working together. He did all the work. I simply provided advice and assisted with expenses. I bought a 2nd hand iPad for Tom and we used Facetime audio and MS Whiteboard to conduct technical conversations. Not quite as good as a whiteboard in the same office, but very close. Do you have access to an iPad and iPencil? If not. I shall investigate getting one for you so we can carry on proper technical discussions more easily. The goal is to have fun playing with a shared project.

Back to the sweeper project. As an example, a pair of ADF4351s, one fixed at 2 GHz and the other sweeping from 2 - 4 GHz would require 2 fixed filters, a 2 GHz low pass and a 4 GHz low pass to cover the kHz to 2 GHz range. There are lots of ADF4351 VFOs with the ability to sweep, but none produce sine wave output. It's under $40 for a pair of ADF4351 boards from China which leaves only the filters, mixer and a suitable MCU (e.g. Arduino, STM32, MSP430, etc). All of that is cheap from China.

This is your project. I am merely here to assist as I can and you request. Though I reserve the right to supply items I deem important to your working efficiently.

Aside from the $4000 I expect to get for the bulk of the tubes, I have 24 VT-4C/211s and 42 VT-52/45 specials. The former sell for $1000 to audiophools and the latter are running $300-400. I have ordered a uTracer 6 and plan to curve trace all the tubes and sell them on ebay with the measured curves for each tube in a set plotted on the same graph.

The graph will be publication quality so they can put them in a matted frame to show off. That's just entertainment for me. The real value is having the commercial space cleared so my sisters and I can sell the property. It's just play money for me. I already have a suite of HP, Tek and other top tier stuff that had a $750k list in the mid '90s. All acquired for well under $30k. Having only bought a single new vehicle, a base model 1993 Toyota pickup for $7800 in my entire life, the lab is the new car I didn't buy.

I'd like to note that so far as I know there is no low cost means of curve tracing transistors except the Peak DCA75 which is painfully slow. There's not a lot to one and a well designed unit sold exclusively through R&L and a few other ham radio dealers might be commercially viable.

Another potential product is an in-circuit capacitoror tester. I have several LCR and ESR meters, but the EDS-88A is the only one that actually works in circuit.. However, it's rather pricey.

In closing I want to emphasize that you are not under any obligation whatsoever. If you develp the next major piece of low cost test kit that's fantastic. If nothing happens that's OK. Life is unpredictable and often turns out very differently than we expect.

I am not a gambler and have never bought a lottery ticket or placed a bet. Simply not interested as I can calculate the odds. In this instance I can't calculate the odds of success. I'm really just bribing my way into someone to talk to.

Have Fun!
Reg

On Thursday, August 17, 2023 at 10:50:25 PM CDT, Daniel Ricardo Perez via groups.io <danyperez1@...> wrote:

Reg,
Interesting idea. It would require a tracking passband filter as frequency is sweeped, to select the desired harmonic. But I fear you should need to have selected the 15th harmonic in the range of, say, 1500 to 2500MHz and mix it with 1500 fixed, in order to cover 0...1000.

I had thought of something like that but with a single PLL. As varactor tuned filters can't span much more than 1:3 frequency, two or more should have to be switched in and out if 1 or more decades range are needed. There would be an unavoidable amplitude and phase transient during the handoff, sweep should have to be stopped until stabilization, and the detector should have to be instructed to ignore during the transition.
If the transients can be tolerated, e.g. ignoring them by software after the detection, there is another possibility: instead of multiple tracking filters, have multiple VCOs, phase locked to the Si5351 thru programmable dividers

I am thinking while writing... Why not combining both ideas? Get 1500...2500 from a single VCO, phase-lock it to 94...156MHz thru a /16 fixed divider, mix it with 1500 locked from another 5351 output.
Lots of ideas, little free time...
Daniel LW1ECP


El jueves, 17 de agosto de 2023, 23:17:08 ART, Reginald Beardsley via groups.io <pulaskite@...> 别蝉肠谤颈产颈ó:
Daniel,'

As you have an Si5351 I'd like to suggest examining using a fast (e.g. Potato Chip) TTL part with sub 1 ns rise time to increase the harmonic content to over 1 GHz, filtering the unwanted harmonics and. mixing the two Si5351 outputs.? This would require some MCU programming, but my initial examination suggests that with proper choice of frequencies and mixer you could sweep the Si5351 from 10 kHz to 1 GHz with relatively little effort.

I plan to work on the frequency plan some more tomorrow to eliminate some gaps in? my attempts. today.? A tinySWEEPER looks to me to be? a viable Si5351 project from 10-100 khHz TO 1 GHz.? That would be a huge boon to the RF community..

Have Fun!
Reg