Tuning Slugs

[Robb]

there's an infinite number to right of point as there is to left, but i'd say you need at least 8 digits on frequencies below 99 Mhz,so you have at least 6 on right hand side of point to read to 1Hz, but there's nothing stopping you being even more critical, just ain't worth it for a CB, but I'd imagine in some instances its very critical to go to much smaller fractions of a Hertz.

As for drift Robb, you ever considered it might not be the external components, but the oscillators, crystal load capacitance that is making it so touchy, it's been noted the radios (export anyway) that slide the most drift the most too, and crystal load capacitance plays a big part on how much effect components round it affect it. Just a thought for you. Temperature plays a big part too.

I understand and agree. But it would be a plus to change out some parts to keep unnecessary temp deviance from influencing both warmup and overall stability. For example, Galaxy radios use some U/J rated ceramic caps - which by their nature can and do cause drift all on their own by that loose/sloppy tolerance rating. Bought some silver/mica caps and and am going to experiment a little to reduce some drift - if possible - by using silver micas in their place (about 10 places altogether in the ref osc, loop osc, and car osc respectively). In addition, changing out the 1N4148 for some JANs to check stray/temp dependent capacitance in the loop osc as well.
Any thought and suggestions/interested/appreciated, George . . .

BTW - Just bought a Rubidium 10mhz osc to align my counters to.

 

[jazzsinger]

I understand and agree. But it would be a plus to change out some parts to keep unnecessary temp deviance from influencing both warmup and overall stability. For example, Galaxy radios use some U/J rated ceramic caps - which by their nature can and do cause drift all on their own by that loose/sloppy tolerance rating. Bought some silver/mica caps and and am going to experiment a little to reduce some drift - if possible - by using silver micas in their place (about 10 places altogether in the ref osc, loop osc, and car osc respectively). In addition, changing out the 1N4148 for some JANs to check stray/temp dependent capacitance in the loop osc as well.
Any thought and suggestions/interested/appreciated, George . . .

BTW - Just bought a Rubidium 10mhz osc to align my counters to.

TBH Robb, i no longer have the test gear or access to it to look into such issues, was mainly giving you other avenues to explore, as i said its been noticed the more the radio slides the further it drifts too, which suggests to me modern crystals don't have the same load capacitance as older uniden ones, they also have ic's instead of a couple of discrete oscillators, funnily enough one of the most stable radios i came across was the grant classic export, but coarse tune on it barely slides 2 Khz, adding high power output, ie more heat hasn't helped the situation either, as most have insufficient heatsinks,

to be honest I ain't so sure its that critical, i've used ss3900's for the last 13 years alongside jacksons, grants and richards (unidens own ss360fm/cobra 148 gtl dx copyrighted upgrade) and I'd be lying if i said the drift ever bothered me, once they reach operating temperature most stabilise too within the 100 hz or so that sp5it suggests is close enough, i tend to agree with him,

its one of those ones, is it really worth spending money on tcxo oscillators on a couple hundred dollar radio, when even a top notch hf set with .5ppm tcxo is classed as bang on withing 54 Hz of the actual frequency at 27.000.000 Mhz. If you can't get the best hf sets that stable is it really worth trying to get a cheaply flung together export or cb to equal it let alone better it.

it would be nice to turn a radio on and see it sit bang on 27.555.000, but it just don't happen, as temperature change alone ensures that not to mention cheapness and tolerance of components, tbh i think most exports actually do pretty well in that department and those who complain about it generally don't realise most radios generally exceed manufacturer and fcc specs by miles in that dept, i think a few radios would benefit from the changes your thinking about, but i doubt the majority would, not for 11m anyway,

there's always some tard in every town/city who thinks his radio is the standard all radios should be judged by, many using frequency displays that aren't even true frequency counters, they will tell people with lesser radios but that have tcxo fitted that they are off frequency, when a true counter reveals its usually them that's off because they're using their clarifier, rit, delta tune rx only shift, but too dumb too realise as soon as they do it ensures someone will be off, its not that critical what the readout actually says, what i've found critical over the past 30 years is as long as your fine/rit is centred and you use the tx/rx coarse or vfo to tune in who your talking to so both of you are on the same frequency irrespective of what the readout says, then it is so much easier for a third, fourth or fifth station to join in without everyone jumping about daft on fine tune/rit.

unless your dealing with top notch hf sets there's not much point being bang on anyway, as no two radios will ever be the same as rarely is every radio in the town or city tuned by the same counter and same concientious tech, thats why all SSB radios have at least a clarifier, and the counters vary less so than radios in the good ones but still vary all the same, you'll drive yourself nuts with stuff like that,

its time you'd be better spending on the radio or learning about other parts of the system that make far bigger differences, just my honest opinion mate, by the time you've sorted it you'll have replaced half the radio, as most components in them are borderline at best, better just to avoid the worst culprits than try and rectify every fuck up or cut corner the maker did. No cb, export or otherwise is worth the hassle. Jazz

 

[Captain Kilowatt]

Just speaking of accuracy requirements, when I was in broadcasting we had to maintain the frequency of our AM transmitters to within +/- 10 Hz which required a display readout down to the last Hertz which would be six places to the right of the decimal point. Maybe CB and ham do not need it however sometimes the accuracy is needed.

 

[Robb]

The Rubidium 10mhz osc is for aligning my test equipment; not for any one radio - lol.
Using questionable state of tune counters has been dodgy at best; even though they are a Fluke and a Hp (these two do not agree).
Radios do drift about; but one does not want the test gear to do that, I'm sure you will agree.

I am going to experiment with the parts I have for now (silver mica caps). Then see what that does for it. Maybe nothing; maybe something (should). Then the JAN diodes. Finally some high stability resistors at key points. Learning by experimentation, such that it is. The issue these change-out parts deal with is thermal stability; L vs C comes after that is dealt with first.

 

[jazzsinger]

The Rubidium 10mhz osc is for aligning my test equipment; not for any one radio - lol.
Using questionable state of tune counters has been dodgy at best; even though they are a Fluke and a Hp (these two do not agree).
Radios do drift about; but one does not want the test gear to do that, I'm sure you will agree.

I am going to experiment with the parts I have for now (silver mica caps). Then see what that does for it. Maybe nothing; maybe something (should). Then the JAN diodes. Finally some high stability resistors at key points. Learning by experimentation, such that it is. The issue these change-out parts deal with is thermal stability; L vs C comes after that is dealt with first.

Lol, yeah i knew the Rubidium oscillator was a calibration source, but even good counters eventually lose accuracy through aging components changing value from heat etc.that's why most professional test gear is calibrated at set periods. My money would be on the HP being closest on accuracy but you never know till you check them.

what i meant was to stabilise a cb you would probably have to fit a tcxo in all oscillators it has to make it stable and it just ain't worth the cost or hassle, maybe on a top end yaecomwood, but no cb i ever had was worth that expense, you may find some improvement with your experimentation but I have a feeling the crystals may be the main source of drift, but you will learn a lot from what you plan doing on just what is and isn't critical or susceptible to heat in these circuits.

Another cause could be the variable inductors, i suspect they aren't the same quality as the Murata ones Uniden used to use, In the cb trade its common practise to cut every cost possible, Uniden don't even use their own inhouse filters like old days now, as its probably cheaper to buy in x thousand of the 10M4D type, certain Uniden ones had tighter skirt factor which changes selectivity, which is why some radios were better than others at adjacent channel rejection.

There's deffo no harm in experimenting, but as CK says even the broadcast industry only required accuracy down to Hz, Even on SSB most people couldn't tell a signal that was 20Hz out, Infact as sp5it pointed out many struggle to hear a signal 100hz off, I don't, but its obvious from the many youtube videos posted that many do, its all down to your hearing and what sounds natural to you.

the trouble with high accuracy counters is the more drift you see that wasn't present on less accurate or ones with less resolution/digits after the point the more it frustrates you, the biggest mistake i see most people make is with the warm up drift, calibrate the radio when its cold and wonder why it drifts off when heated, you may reduce that drift but i doubt very much you can stop it altogether, a good tech will leave radio on for 40 to 6 minutes before even attempting an alignment, that way it is off when you turn it on and it comes bang on when heated, i find once heated the drift on most radios is negligable, at the moment i only have a 7 digit counter which ain't the most accurate, but I have aligned a couple of radios with it and been damn near close, and once heated they don't drift much, even the humble ss3900 (although i have better radios) which is my workhorse don't drift that much when heated, if at all, i certainly don't notice it, although mine is an early 3900, i do notice the warm up drift but i never just bang on the radio and get fired in, i let it do what it has to do before i start using it.

Good Luck with your experimentation, but i wouldn't get too hung over a few Hz drift no-one will notice anyway, its like trying to squeeze the extra watt or two no-one will ever notice, it fast gets to the point of diminishing return for bucks that would be better spent down the pub or on a bit of puff, lol, the latter in my case, when people tell me i'm off frequency i just laugh, usually because a kenwood, icom,or yaesu or even worse a lincoln or 2950 says so, they just don't grasp most of these radios have frequency displays, not proper counters, and are only as accurate as the person who set them up or degradation of time allows, you take them in the house, show them your oscillator frequencies and add them up and it may or may not be 20 or 30 Hz off, but their yaecomwood told them It was 100/200Hz off, how can that be? next thing you know their selling their radio,wtf?

its fucking unbelievable this thing people have about frequency accuracy, especially on 11m, it just ain't that critical, If i can hear you clearly and your audio sounds natural, i couldn't give a toss what frequency or how far i need to move my coarse tune to align them,if its really bad i might suggest they get it aligned, but for less than 500 hz i ain't gonny say shit, as it will gradually get worse with time and then i'll suggest they spend the money, i've known guys in the past who won't even answer anyone who deviates from them being bang on 27.555.000 on their display, too much like hard work, or shock horror god forbid their display may need to read 27.555.030 to sound natural, lol.

Just watch you don't get too caught up in that sort of madness mate, and good luck with the learning, and calibration of your counters , but at the end of the day, never lose track its only a hobby and not really worth investing mega bucks/time in, unless your going to do it for a living, there's far more enjoyable things in life with a lot less stress lol.

Meanwhile i'll sit back with a joint and ponder what im going to do with the two N.O.S CLR2's i just bought, lmao, fuck I could have toured the world for years with the amount of cash i've wasted on radio/radio gear only to go full circle and realise a 3900, KL203p and a right good antenna will compete with any hf set on the market on 11m, I won't even consider what i could have done with the cash i wasted on weed, its too staggering an amount to even think about after 3 decades off puffing. Nostalgia is a costly habit, lol.

I hope you find the answers you seek Robb, but tread carefully moneywise, you don't need to spend vast fortunes to work the world or sound good doing it and perfection isn't everything. Sometimes a good chill is the best answer of all

All the best Jazz.73

 

[Captain Kilowatt]

its fucking unbelievable this thing people have about frequency accuracy, especially on 11m, it just ain't that critical, If i can hear you clearly and your audio sounds natural, i couldn't give a toss what frequency or how far i need to move my coarse tune to align them,if its really bad i might suggest they get it aligned, but for less than 500 hz i ain't gonny say shit, as it will gradually get worse with time and then i'll suggest they spend the money, i've known guys in the past who won't even answer anyone who deviates from them being bang on 27.555.000 on their display, too much like hard work, or shock horror god forbid their display may need to read 27.555.030 to sound natural, lol.

One thing that irks me is that when I call a general CQ on something like 14.147 (I usually make a point to be at least on the nearest full KHz just for logging purposes) and the person that responds tells me I am off frequency. WTF??:blink: If I am calling then I am DEAD ON frequency....my frequency. Even if I was on 14.147.3 I am still dead on MY frequency. On the ham bands there is no such thing as channelized frequencies except on 60m. People,especially some of the newly licensed 11m newcomers, seem to think that everything should be on the "zeros" or "fives". If that was the case we would have channel selectors instead of VFO's.

 

[Captain Kilowatt]

As for calibrating a counter, before Rubidium standards were readily available we used to use a stable frequency oscillator with vernier tuning and a receiver with a signal strength meter. The oscillator was coupled to the receiver along with the antenna but isolated with a small RF amp so that the oscillator would not feed back thru the antenna and be radiated.We would tune to WWV and carefully tune the oscillator for a perfect zero beat on the meter. As youy approached zero beat the signal meter would start to waver at the same rate as the difference between the two signals from WWV and the oscillator as the two signals went into and out of phase. if you were off bu 5 Hz the meter would waver at a rate of five times per second. With this method it was possible to tune the oscillator to EXACTLY the same frequency as WWV right down to the last Hz. When the meter peaked and stayed there you were dead on. The counter to be calibrated simply read the frequency of the oscillator which matched that of WWV. Using this same method we were able to check the frequency of our various AM transmitter sites (or any other AM site) remotely from the office rather than visit each site. We would simply tune into our transmitter frequencies rather than WWV and then tune the oscillator for a perfect zero beat and look at the counter display. It was determined by Industry Canada to be a perfectly acceptable and accurate method of remote frequency determination. It was interesting to sometimes tune into other broadcast stations and see how close that were.

 

[Tallman]

When I'm looking at the 30 MHz range there are seven digits to the right. It measures down to the tenth of a Hz. If I go higher in frequency the more digits are used. Example 30,000,000.0 Hz is 30 MHz down to a tenth.
What I was really complaining about is the output carrier shifted to 24 MHz when closed up. The only reason I'm so strict on the frequency is for SSB and it is my son's radio. I have decided to scrap this radio and and buy him a decent radio.