EMRFD Message Archive 11669
Message Date From Subject 11669 2015-09-25 19:18:47 farhanbox@gmail.c... Atlas 210x reboot Allison
atlas 210x is about the only commercially produced transceiver that i have wished to own. it was the first transceiver that i ever saw and operated for a few minutes. it has a ladder filter, a diode dbm mixer and a strong post mix amp. here are is my list of things to do with it.
1. change the vfo to use a low noise jfet. add a Huff n Puff stabilizer.
2. replace the band pass filters with better triple tuned ones with low loss
3. the if board has to go. thr MC1350p was a noisy device. the noise would go up as the gain was reduced. the Haywards design even with two cascode stages will do wonders.
4. reduce the power to 10 watts with one of the RD devices.
i would also want to change the mixer to KISS mixer with 2N7000s and eliminate the post mix amp but that would be changing the soul of the machine.
the other trouble was too much tx gain in three stages. but then i operated it only for a few minutes into an inverted V. so i cant comment upon it from experience. how much does an atlas 210 carcass go for these days?
- f
11670 2015-09-25 22:42:04 Kirk Kleinschmidt Re: Atlas 210x reboot Farhan,On ePay here in the States, untested "fixer uppers" go for about $100, while used units that apparently work fetch about $200.Best of luck. Perhaps you'll turn it into a 210-BITX ? :)--Kirk, NT0ZMy book, "Stealth Amateur Radio," is now available fromwww.stealthamateur.com and on the Amazon Kindle (soon)
11671 2015-09-26 06:55:11 Ashhar Farhan Re: Atlas 210x reboot hmm .. that's an idea. the trouble with being afar from the americas is that the postage is often costlier than the purchase. as a result, i time these things to coincide with the migratory patterns of my academician friends who come to india during their winter and summer breaks.i am over-prepared for the 210x :-)- f11675 2015-09-26 13:03:48 bob_ledoux Re: Atlas 210x reboot Be careful for what you wish for. Ashhar will drive the Atlas 210 price skyward.
Remember how Bill, N2CQR, drove up the price of Drake 2-B's by his comments on the Soldersmoke podcast. Heathkit QF-1, Q-multipliers with their vernier variable caps were cheap until Bill let that cat out of the bag. Now, I'm forced to use varicaps!11679 2015-09-26 17:27:27 kb1gmx Re: Atlas 210x reboot Some of this is likely going to get me some hate mail from Atlas lovers
and owners. But just for a moment put emotion aside. I really don't
hate it. I am however being critical with the advantage that in 40 years
we(collective and myself) learned a lot about radio and transceiver
design. Its a groundbreaking radio with things that were a result of
pushing the bleeding edge.
1. change the vfo to use a low noise jfet. add a Huff n Puff stabilizer.
Been done by others. Has potential but putting a FET the VFO alone is not a cure.
The problem of the VFO is its band switched and for some bands runs at frequencies
that are over 20mhz, it takes a lot of finesse even with a stabilizer to keep it from
drifting excessively fast and popping from lock to lock. There are two sources
of drift in the VFO the device and the LC. The device has a varying LC so its
operating point changes from band to band. The drift from that is improved by
adjusting bias on each and every unit for best stability. Then the LC system
has to be temperature compensated. Of course that more than 40 years has
elapsed helps none of that. It doesn't fix the excessive level of harmonics
resulting from its design. It would still need a digital display as the analog
is mechanically frail plastic from ageing.
Three fixes that have to be applied in my mind. Insure the VFO power is
stable replace their with a low dropout regulator. Change the bias on teh VFO
oscillator to find the zero drive oscillator operating point. That's recognizes
that every transistor used for that function had a different Hfe (and generally
still do). By doing that on the one I have under 20hz on 40M is doable in a
stable temperature desktop. before that it would drift down at 200hz per
minute and would never settle. NOTE on this bias change if you went to
far it would drift the other way and never settle. also the caps used
must be replaces with good COG parts first. It still will drift from heat but
that's the LC.
The VFO is the biggest single problem. A Si570 system might work well there.
A DDS with low SFDR can work there too (9951). Either that or a good single band
VFO with a offset tracking PLL to get in the range for other bands. The
challenge is space and keeping it clean.
Did I mention its a tiny radio for then and maybe even now.
2. replace the band pass filters with better triple tuned ones with low loss
Triple tuned with low loss, somewhat contradictory. That and space, your
mod would entail be making your own boards. Making new boards however
can be an improvement alone by going two sided and better grounding.
Maybe shielding improvements.
In some places and cases better parts alone would be a net improvement.
3. the if board has to go. thr MC1350p was a noisy device. the noise would go up as the gain was reduced. the Haywards design even with two cascode stages will do wonders.
This is less a problem, the reason for that is by time the AGC starts your dealing
with fairly large signals and added noise is not an issue. The radio has other
compromises that have far more impact but yes there are a few 1350s. Haywood
is not wrong, only that in this radio its impact is low.
The radio is unique as its a low gain SSB (very unique for then) and the receiver
gain is limited to the post mixer amp and 1 stage of 1350 and a DBM product
detector. For the receiver that all of the RF gain used and about 15-20db of
that is offsetting the input filter, 1st DBM, Crystal filter, and 2nd DBMs losses.
Its usefulness on the air is enough audio gain and a low noise front end without
a preamp (so high loss input filters can kill you there). The liability is the Rx input
filters are also the TX band pass filters and that would impact TX gain distribution.
Also going from 1350 to a Hycas mean a total rework of the ALC and AGC system.
The 1350 has a threshold of about 5V and give positive from there, Hycas has a
threshold about 2/3rds the power rail and goes negative from there.
Change that and your making a new SWR, AGC, and metering board.
4. reduce the power to 10 watts with one of the RD devices.
The driver is in the watts range already. RD parts at 10W are not a absolute panacea.
A good bipolar is a valid choice too. If anything I'd not use one for that stage but go
push pull for better power efficiency with RD or BJT. It would be easy to do that.
The amp itself (driver and finals) bolt onto the back easy to remove and restyle.
The above 4 mods if done would impact most every board in the radio, some would
have to be a complete overhaul. It would make an interesting radio.
To understand the radio and its topology read about the "Lichen" in EMRFD
its the same topology and the discussion over stage reuse, gain distribution,
and its liabilities is eyeopening. The design was high performs to a point and
that point is limited by the switching CIO and VFO sources and other
limits inherited. That's not to say its bad only that you can't make the next
super radio of it. Its a good exercise in even with DDS or NCO for the LO and
modern hardware your get smaller but physics of electronics limit your much
better it can be. Sorta once you open the can your get the full distribution
of worms.
I have a bit more contact with them over the years fixing a few. I have one
in my hands as I write but its a nice unmolested one and I'm not ready to
do terrible things to it. I'm looking for one with blown finals and "issues"
as a test bed for ideas. As I said it would be an interesting radio to modify.
There are other older radios out there for modding as well. There are a few
IcKenYae and older TenTec radios that are sold state up the driver and final
that could be solid stated (new driver and final all solid sate) dumping the
HV power needs and heat issues like VFO drift.
Plenty of fine radio candidates.
Allison
11680 2015-09-27 03:55:04 Ashhar Farhan Re: Atlas 210x reboot hmm .. i agree allison, the truth me told i used one almost 25 years ago for a few hours. i have never peeked inside one. most of the new radios confuse the hell out of me. there are so many knobs to fiddle that i am nervous that i'd leave some (like transmit offset or something) turned on. as a result i like simple radios like the Atlas and some TenTecs.- f11681 2015-09-27 04:24:45 blumu Re: Atlas 210x reboot I agree with both of you. My favourites are my Atlas 210X and Century22 (in addition to
homebrew receivers) - not least because I can understand and maintain them :-)
Michael
UK
----- Original Message -----
11682 2015-09-27 05:21:29 kb1ckt Re: Atlas 210x reboot I have a relatively simple TenTec, and have managed to leave RIT on just the same. It happens.shawn kb1ckt
Sent from my iPad11683 2015-09-27 09:49:51 kb1gmx Re: Atlas 210x reboot I can see that I tend to fall in that realm. I seriously not a fan or "menu" radios.The FT817 its tiny I understand that but there are others that just make me scream.The Atlas is a simple radio and that has appeal to me. It part of the reason I like myTentec Triton (M540), simple analog radio that works and sounds good.Allison11684 2015-09-27 09:57:45 kb1gmx Re: Atlas 210x reboot Oddly I have four radios I call modern.Tentec 6n2 my main radio for 6 and 2M with a pair of amps its the ticket.Tentec Eagle Heck of a good HF+6.. I have yet to hook it to a computer, may never.Tentec Triton M540 the analog side rule dial killer receiver for a solid state radio built in 1978.FT817, small and does DC to daylight (ok HF through 432 skipping 222) its the portable do all.The rest are HB SSB radios at least count 7 of them all monobander or purpose built andanother in the works. They have sparse panels as a rule. Volume, tuning, maybe RF gainor attenuator switch. One even has a mic gain, had to fill a existing hole with something.simple is good. ;)Allison11692 2015-09-28 03:52:17 Fernando Krouwel Re: Atlas 210x reboot Hi Allison, good morning:
I have the 5.52MHz xtal filter (and also the small board containing the BFO/carrier oscillator) for the Atlas transceiver, which I purchased some time ago in a flea market. I would like to use them in a small project, probably a BITX or something like.
Do you have any information about this filter, like input/output impedances and if it is (or not) bidirectional?
73' s
Fernando - PY2FZU
11693 2015-09-28 04:07:38 kb1gmx Re: Atlas 210x reboot Do you have any information about this filter, like input/output impedance and if it is (or not) bidirectional?Ok this is from Clint not personal testing.Filter about 800 ohms. Its assumed both sides of it are the same. It would not be hard totest that.All crystal filters are bidirectional for signal.Find a copy of the manual on line I'd suggest the Atlas 180 as its representative and also simplest.It would not be hard to duplicate the radio save may be the final amp and the VFO system whichare the two you would least want to do. VFO a high end DDS should do and final for low powerthere are published options to a few watts. Oddly enough the whole radio has no parts that Iknow of that are not still available. Examples are the MC1350 IF amp, LM380 audio, Ca3089transistor array that can be done with either discrete transistors(3904) or Ca3046 (same part,better specs). About the only thing you cant get new is the finals, filter, and sheet metal.Allison11694 2015-09-28 04:24:56 Fernando Krouwel Re: Atlas 210x reboot Thank you very much!
Fernando
11698 2015-09-28 23:54:04 John Lawson Re: Atlas 210x reboot What is the physical measurements of the filter, length, width, etc. also does the filter have Network Sciences as the manufacture stamped on the top of the filter case? Any other markings stamped on the filter would be of help.....finally do you know if it is the SSB filter or CW filter.....If so, I may be able to provide you with some information. Let me know as I do have some of their filters in the junk box........John K5IRK
Sent from my iPad11699 2015-09-29 04:03:57 Fernando Krouwel Re: Atlas 210x reboot Hi John, good morning:
For more details I would have to look for it, but I remember, yes, it is made by Network Sciences, 5.52MHz and the writings appeared to be simply stamped on its metalic case. It was not with a beautiful looking, so I polished it with a... metal polisher (stamped infos disasappeared then), that removed the last layer of plating, leaving it with a copper looking (before this polishment it had a very ugly looking that was even difficult to read the maker and other infos). One thing that I observed is that it didn' t have the input/output id. Also I was not capable to locate these pins ID in the Atlas Manual.
About the BFO/Carrier oscillator, I tested it and works OK, both sidebands.
I thought about building a simple SSB transceiver or the Progressive Receiver with it.
In our present days, the Progressive Receiver has became easier to build, since now we have Si570, Si5351 and some simple and cheap DDS, wich enable us to build it multiband with single conversion, avoiding those expensive and hard to find (custom made) xtals needed for the converter.
73' s
Fernando - PY2FZU
11700 2015-09-29 04:34:38 John Lawson Re: Atlas 210x reboot Hi Fernando, give me a day or so to find them in my junk box. Also if you have the schematic diagram which shows the filters, if you can scan that part and send it to me off line at jmlcs2000@yahoo.com it would help me to see if mine are the same. Finally do the physical measurements of the size of the filter case too. I have several of their filters and there is one that is smaller than the others......Finally I'm curious as to the frequencies of the BFO crystals.73, John
Sent from my iPad11701 2015-09-29 07:21:52 kb1gmx Re: Atlas 210x reboot With those filters the input and output are not marked and are reversible.The actual frequency of the carrier osc has to be set (trimmed) in the systemfor best results and is rarely exactly the marked crystal can frequency.Allison11702 2015-09-29 08:43:22 atlantaswl Re: Atlas 210x reboot Hi Fernando,Concerning your thrid paragraph, I just completed the digital infrastructure for a 16-band progressive communications (W7ZOI and K5IRK) receiver supporting 4 crystal filters. I am currently using 2 AD9851 for both the VFO and heterodyne oscillator. All the band pass filters are built and aligned; the IF amp is the hybrid cascode (W7ZOI and WA7MLH). The design is still single conversion for 80 meters, dual conversion for all bands above 80 meters.Communication to the band-pass filter relay board, the crystal filter relay board, and the two DDS boards is SPI, and parallel to the display. This has been a fun project.73s,Fred KK4VEP11705 2015-09-29 16:33:32 Fernando Krouwel Re: Atlas 210x reboot Hi Fred,
All I have to say is:
Wow, congratulations!!!
Fernando - PY2FZU
11706 2015-09-30 09:47:11 kb1gmx Re: Atlas 210x reboot Hi Fred,A curious question: Back when the progressive RX was introduced the primary issue in any radiowas a LOs system that was stable. That meant a 160 or 80M radio. Even in the article it noted thatmultiple conversion had cost in dynamic range by the payback then was a stable receiver and abilityto later add bands. Earlier influences were when using IF int he 455 or 500khz range meant multiple conversion to avoid image response above 80M. But by then a filter in the 9mhz range meant few ifissues up to 6M and beyond.Fast forward 40 years:The image issue is long gone. We routinely build good IF filters at HF and higher with 5 to 12mhzbeing most common for home brewers and 4.9152Mhz being plenty high enough for 10M.The VFO issue is solved. We have SI570 NCO and high end (low SFDR) DDS available theAD9851 being an example. What makes these device appealing is they are easier to implementthan the multi-loop PLLs commercial radios opted for.The question: why multiple conversion as single conversion has become easier? Just dial theLO to where you want to be and switch in a new front end filter?After all everything after the input to the first mixer doesn't change.As a VHF-UHF sort there is logic for converters /transverters/ for bands 2M and up.Up there band switching becomes impractical and dynamic range less an issue butnoise figure is.Mostly thinking out loud as someone that have spanned the days when a filter wasa costly and rare thing (McCoy, SI, and Collins) and you built with what you had tonow when you make a filter to suit needs.Allison11707 2015-09-30 12:18:11 iq_rx Re: Atlas 210x reboot Hi Allison,Thank you for giving us the benefit of your thinking out loud. Something you didn't mention is that single conversion receivers have many fewer internally generated spurious responses. It is generally possible in narrow band applications with good shielding to build receivers that have no internal birdies across the desired tuning range. This is critically important when digging for weak signals, either while tuning across the band noise and listening, or using a DSP engine to dig deep.In the late 1980s I experienced many hours of frustration while tuning for 1296.1 MHz CW signals from 450 miles away, hearing something very weak, tuning back and forth to see if I could discern any keying, and finally turning off the converter and discovering it was still there on the Collins 75S3C IF receiver...an internal birdie. My first phasing receiver system was designed to replace (and outperform) the Collins 75S3C in that application. In critical UHF weak signal applications I've used single conversion systems ever since.An original motivations for all the work I did on phasing receivers and transmitters was that I could build single conversion systems with a VHF or UHF IF, and still get rid of the opposite sideband noise and signals on the other side of zero beat.My single conversion homebrew stations for HF through 5.7 GHz are all spur-free over the entire range of the tuning dial, something I couldn't say about any of my multi-conversion commercial gear.That early motivation for my direct conversion receiver experiments sometimes resulted in a humorous disconnect with the QRP community. My QRP friends all seemed to be on a mission for simplicity and minimum parts count, and I was designing something that would outperform a 75S3C. Most of the world thinks of direct conversion as a way to reduce cost and complexity. I've always approached it as a way to improve performance.Best Regards,Rick kk7b11708 2015-09-30 12:53:31 Tayloe, Dan (Noki... Re: Atlas 210x reboot Amen to non-simple and high performance. I like to use R/C active filters in my DC phased receivers. 14 poles of low Q active R/C filtering is a joy to listen to, but is not particularly low parts count. I think I almost killed Dough Hendricks when Norcal kitted the NC2030. Over 400 parts for a “simple” DC CW transceiver? Lots and lots of Rs and Cs with too many unique values. I could do much better today minimizing the number of unique parts, but for a phasing DC receiver, parts = performance.
- Dan, N7VE
11709 2015-09-30 20:12:18 kb1gmx Re: Atlas 210x reboot I learned the multiconversion lesson by building one, ok I'm dense, several. Why several.Because I was young, uneducated, and didn't understand spurs. It taught me well. Ilearned shielding, circuit bypassing, isolation, and filtering and then to just not go there.Regardless of the technique some older designs persist for wrong reasons.That's not saying the progressive was wrong, it was very good. Only thatlittle details were not spelled out as to why and what. For example If youbuild the progressive and put each converter in its own box and plug it itit works well if the main RX is in a box. I knew someone who knew morethan me and he put each converter next to each other visible to the mainchassis. Havoc, the only word for the result. He would take the wholething apart box each section and each converter, in the end it workedvery well. However he did it twice.There is a difference between simple to me the R2 is simple and minimumart where even bypass caps are often left out to make a lower parts count.The later is also known ans Munsoning after "mad man Munson" of earlyTV manufacturing. He would hover over engineers and start pulling partsout till it would stop working and then say put that one back and ship it.Simple to me is systems devoid of issues by doing things at audio ratherthan at 10mhz for the same effect. Its simpler to build and troubleshoot.As someone that has designed and built computer systems with manyhundreds of chips more parts is not complex its just more parts. Alot of simple stages is simple. Complex is when there are a lot ofthings and any go wrong it all fails and make catastrophically.Complex is a test setup that takes an amount of gear to make a labengineer envious to make it work.If there is a bottom line and your duplicating a older design read thewhole article. Read the other peoples war stories.Look at similar thingsand see what that writer/builder had to say. Look at the picturesand take a shot at why the writer/builder did it that way or shouldn't have.Make a point of building as experimental so if a circuit doesn't workas planned it can be replaced or fixed. Then enjoy the build.Allison11712 2015-10-01 08:45:56 atlantaswl Re: Atlas 210x reboot Hi Allison,Thanks for responding to my post. There are a number of reasons for the approach I took.First, this was the first receiver I've built from the ground up after Kitchen's regenerativereceiver. The article by Wes and John looked doable with my skill set (mathematics vselectrical engineering background), but with lots of kit-building experience.I started with the assumption I would be able to acquire all those crystals for the heterodyneoscillators. After some research, I realized I would have to go with digital synthesis. Withthe dual conversion, the VFO range would be limited to 12.5 to 13.2 MHz for all bands,except 80 meters. I am able to turn off the heterodyne oscillator when tuning 80 meters.To lessen the effects of any spurs, I could use a low pass filter that will attenuate thosespurs outside this VFO range. Another benefit was the ease of programming the microprocessorto control the VFO, set the heterodyne oscillator, apply the offset per band to display the correctfrequency being received, and select the band pass filter, all with one button push on the frontpanel. I am much more familiar with software engineering than I am with RF design. I amlearning a lot on this forum.I do plan on quite a bit of shielding. All band pass filters (14) , the BPF relay board and 80 meterpreselector are on the underside of the chassis. The VFO and heterodyne oscillator are inHammond 1590A enclosures with sma connectors for output and bypass caps for control andVcc. The BFO oscillator (crystal-controlled) will also be shielded similarly on the underside ofthe chassis. The IF amp, both mixers, microprocessor board, digital signal routing board,crystal filters, relay board for these filters and audio amp are all 'above ground' and are currentlynot in enclosures. I plan on providing enough space on the top side of the chassis betweenboards to provide enclosures for any of the boards, if I need it. All RF signal routing will bethrough RG-174.I've got a lot of SMA male connectors to attach to the various boards. Does anyone have adecent SMA torque wrench they could recommend?73s,Fred KK4VEP11713 2015-10-01 09:06:22 Jim Strohm Re: Atlas 210x reboot Jim N6OTQOr -- just buy an SMA torque wrench. I think they're about a hundred bucks new. I know a guy who occasionally has some for $25 each, but they're surplus, and hence they aren't in current cal.Then measure by feel how much pressure you need to meet the recommended spec.Yeah, I've got one that says "5/16" on one end and "Snap-on" in the middle of the handle part. It's all nice and shiny with triple chrome plating.While it's not best practice, you'll get "good enough" connections at HF simply by getting SMA connectors somewhat tighter than finger tight with a small wrench. If you are a stickler, get an inch-pound torque wrench, set it for the manufacturer's specs (you DO know who made your SMAs, right?) for the connectors, and then find a solid way to hook your 5/16" open-end wrench to it.
7311714 2015-10-01 11:29:19 Steve Dick Re: Atlas 210x reboot Hi Dan. I’ve been a fan of the NC2030 but it was no longer available when I first came across it. When you said “I could do much better today” in reducing parts count, I think a lot of people would be interested in a parts-reduced design with similar performance. Any thoughts on NC2030 simplification would be appreciated. Maybe it’s time for a new kit??Regards,“Digital Steve”, K1RF11715 2015-10-01 11:35:12 kb1gmx Re: Atlas 210x reboot I'd create a separate topic for the forum on that project. Keeps them from all getting munged together.For SMA at work a torque wrench.For the rest of the time a very short 3inch 5/16inch wrench. over the years I've acquired acalibrated finger. Doesn't hurt there is some latitude.As to RG174... I hate the stuff. Melts, fragile, lossy. I use RG316 PTFE easier to work withmore controlled loss. For things that need it there is a double shielded version. Ut141-50vendable hard line is a handy items too. I get that from Fleas as there is always somecheap to free with SMA connectors.Allison11716 2015-10-01 14:26:44 Tayloe, Dan (Noki... Re: Atlas 210x reboot Actually, I was referring to reducing the number of “unique parts”, not the total parts count.
However I have learned a few things since then. That is the point in building and experimenting. If I were to do it again, I would certainly change a few things.
- Dan, N7VE
11717 2015-10-01 19:04:03 kb1gmx Re: Atlas 210x reboot I understand what you said only that lot of simple parts Rs and Cs are only anissue to kitting it (production) and required attention of the person assembling.Understanding what that part is or does is repeated to the extreme.If it were so many toroids, they are simple things but winding them scarespeople for reasons I have yet to grok. If they are each different it speaks toskill of the builder. They must be made, terror is often what I hear.When I said hundreds of ICs, same deal, they weren't all the same, but themarkings are on each and it was identify and insert. That and there werelarge numbers of the same thing repeated. The complex part was themaybe 10,000 plus wire wrap wires all going from some point to anotherpoint.I understand that kitted designs seem to appeal more if the total partscount is small. That is also counter sometimes to extending the designin ways that improve it. The best example is AGC, I've seen more reasonsto leave it out. The best was it "complicates the design". Really? We builda whole transceiver maybe but another 5 or 10 parts (likely less) is a bigdeal. The addition of AGC means we can have ear saving and likelymore comfortable experience listening.When yet another a minimal design pops out people flock to it andoften for reasons that are more emotional than design or even bestpractice. I see that every time I listen down around the QRP part ofCW or SSB segment where I hear chirpy, drifty, sometimes evenbuzzy CW, and SSB with the VFO or maybe the CIO FM modulatedor drifting. All it needed was a bit more of something to insure thatwas not the case.Excuse the rant.Home brew should work well too. There are plenty of examplesthat do and some cases exceptionally well.Allison