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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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12th Jul 2019, 10:11 pm | #1 |
Triode
Join Date: Jul 2019
Location: Harwich, Essex, UK.
Posts: 39
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AM FM alignment
Hello,
I am really enjoying restoration of vintage radios and hifi but have hit a stumbling block. Can anyone recommend a good tool/system to align receivers and radios in the LW/MW/VHF bands? There seems to be some older stuff and some new Chinese stuff available and I am very confused ! I have a good oscilloscope and multimeter, but only a small cheap kit sig generator that looks like more of a toy than anything else ! |
12th Jul 2019, 11:38 pm | #2 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,783
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Re: AM FM alignment
You have all you need to do basic AM alignment. You just need a variable oscillator capable of producing a modulated signal at the appropriate RF and IF frequencies. Actually, you don't even need that and can align using off air signals, but a signal generator makes the job easier.
For FM alignment you really need an FM sweep generator (aka wobbulator) which you use in conjunction with a scope. Remember that old radios don't normally need realignment (particularly IF realignment) unless somebody has been twiddling. |
13th Jul 2019, 5:05 am | #3 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,923
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Re: AM FM alignment
A signal generator can be very simple, but it needs to contain the RF signal inside a good metal box so that the only signal that comes out of it is the one that goes down its screened output lead. That way, you have control over the level that's coming out and the injection point where it's going in to the receiver.
What you need to avoid are signals going into the receiver via mains cables or any other unintended route. B
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13th Jul 2019, 7:11 am | #4 |
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Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
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Re: AM FM alignment
The question crops up from time to time.
The reality is, there is no escaping the fact that the only way to do a proper alignment is with a proper generator with digital frequency metering, a proper attenuator & shielding, a known output impedance and levels and that fully covers the frequencies of AM & FM radio bands, and does sweeping too. So as always, I recommend the PHILIPS PM5326. It is not nearly as expensive as some other generators but it is well made and perfectly suited to the task and a compact unit. Likely, if you use cheap generators and cobble something together from pcb's and wire nests on the bench, what you will achieve is a poorer alignment than when you started in the first place. Also, never forget, before attempting alignment, measure the sensitivity over a range of frequencies and the frequency calibration of the dial and document it. Otherwise, when you have finished your alignment you may remain clueless as to whether you have actually improved the radio, or in fact, made it worse. You can however compare the sensitivity with manufacturer's spec, and for that of course you always require a proper generator/attenuator with known levels & impedances. In summary, the notion of any kind of cheap generator for "alignment work" is an oxymoron. A high standard instrument is required, that is if you want a high standard outcome. |
13th Jul 2019, 7:33 am | #5 |
Dekatron
Join Date: Apr 2009
Location: Oxfordshire, UK.
Posts: 4,923
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Re: AM FM alignment
Well, there are no PHILIPS PM5326 on ebay and business sellers are listing them as "Price on Application". I suspect that sig gen far exceeds the standards of anything I've ever owned during the last ~60 years.
B
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Saturn V had 6 million pounds of fuel. It would take thirty thousand strong men to lift it an inch. |
13th Jul 2019, 10:24 am | #6 |
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Location: Maroochydore, Queensland, Australia.
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Re: AM FM alignment
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13th Jul 2019, 11:38 am | #7 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: AM FM alignment
An ordinary old style service type signal generator along the lines of an Advance E2 or some of the AVO's or Taylor etc will do most things you will need, they were the go to generator when I was in the servicing trade, you can check the calibration of one against transmissions of a known frequency, if it's accurate enough on the generators scale then you can take it that that accuracy will be across the range selected and you won't need a frequency counter to check the frequency, handy though they are.
I wouldn't recommend a lab grade all singing all dancing job for a beginner, some praise them but it's a bit cuckoo land for ordinary radio repairs and alignment. Some of these old generators might not do full coverage of the VHF FM band but it doesn't really matter as in most cases you can tweak the VHF Osc/RF using a transmission of a known frequency and your ears, a lot of manufactures also gave FM IF/Discriminator alignment details using spot frequencies as well as using a sweep generator thus enabling a bog standard service signal generator to be used as they covered the FM IF (usually 10.7MHz in most cases) no problem. Lawrence. |
13th Jul 2019, 1:49 pm | #8 | |
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Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
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Re: AM FM alignment
Quote:
However it is not really correct for SW radios, especially those that tune to 30MHz or FM radios. The cheap generators with analog dials and no digital frequency metering and absence of attenuators and known signal levels are just hopeless toys. To set up a discriminator, ratio detector etc properly requires a sweep. Sure there are shortcuts that "work", but you will never know for sure if you have got it right. It all depends on the importance you place on proper alignment and if you are prepared to accept average. |
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13th Jul 2019, 2:01 pm | #9 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,783
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Re: AM FM alignment
Yes, professional communications receivers require lab grade equipment and highly trained technicians to align them properly, but I don't think the OP is referring to that sort of thing.
Whenever we get threads discussing essential workshop equipment there are always a range of opinions, everything from 'twiddle until a faint station sounds best' to 'don't touch it without dedicated clean room facilities'. This just reflects the attitudes, training and experience of the various members. Many members have a professional electronics background in design or maintenance, and are used to using professional workshop gear. To them it's natural to use pro gear even for very basic vintage work. It helps that they've often managed to 'liberate' very expensive equipment from their day jobs following refits or reorganisations. |
13th Jul 2019, 2:17 pm | #10 |
Triode
Join Date: Jul 2019
Location: Harwich, Essex, UK.
Posts: 39
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Re: AM FM alignment
Thankyou for all the considered responses. I aim to keep up the hobby and will be repairing/restoring some fairly high end vintage receivers for myself and friends as well as the odd 70's radio. I love the challenge of getting the alignment set properly and I am really bad when it comes to using shortcuts or rules of thumb with this sort of thing; if I start something, I always want it to be the best it can be (my wife seems to think I am a bit autistic). I will keep an eye out for some decent kit on ebay. I dont mind spending £3-400 if the right piece of equipment comes along. I was a bit scared off when I looked up some of the kit used on youtube to find it was in the multiple thousands of pounds. I will keep my eyes peeled and post back here before I commit to buy. If anyone has spotted anything that might help me do the job online (in europe) could you post me a link please. If anyone thinks they may have something suitable for sale please pm me. Thanks again for the great advice. James
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13th Jul 2019, 2:25 pm | #11 |
Triode
Join Date: Jul 2019
Location: Harwich, Essex, UK.
Posts: 39
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Re: AM FM alignment
Also thank you for recommending the PHILIPS PM5326 - it looks just the sort of thing I am after.
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13th Jul 2019, 2:38 pm | #12 | |
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Location: Maroochydore, Queensland, Australia.
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Re: AM FM alignment
Quote:
https://www.lot-art.com/auction-lots...-18.7-catawiki I mentioned these generators before on this forum as being a good option for radio alignment in a "sensible" price range. I have seen some vintage professional Marconi generators for truly nutty prices and I'd never buy one. Also, I like the way Philips built this generator, very well done electrical & mechanical design. They also chose an excellent frequency counter IC made by Intersil. All in all I'd give them a 10/10 value for money. |
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13th Jul 2019, 2:55 pm | #13 |
Hexode
Join Date: Jul 2009
Location: Wokingham, Berkshire, UK.
Posts: 437
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Re: AM FM alignment
I would suggest that a Philips PM5324 would be a better bet as it seems specifically designed for AM/FM radio alignment, with expanded ranges at 470KHz and 10.7MHz, and full coverage out to 110 MHz
I paid around £120 for mine from The Netherlands. I also have the original manual for it and "WMEBill" certainly has a copy of it. John |
13th Jul 2019, 3:32 pm | #14 | ||
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: AM FM alignment
Quote:
With domestic shortwave receivers make sure the Osc is on the correct peak ie: Trimmer peak at the lower capacitance setting (Fo=Fs+IF) not the higher capacitance setting (Fo=Fs-IF) this can easily happen on some receivers that have a large tuning range and a cramped scale relative to frequency on shortwave on the high band, the tracking won't be right and the performance will suffer, but forget that with a Marconi CR300 'cos it's t'other way round on the highest band (Fo=Fs-IF) Lawrence. |
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13th Jul 2019, 4:49 pm | #15 |
Octode
Join Date: Jul 2014
Location: Petersfield, Hampshire, UK.
Posts: 1,043
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Re: AM FM alignment
If you have one of these Philips PM5324
Not working on all ranges check the reed switches which switch in the various coils Mine has a few that were o/c even when energised! Cheers Pete |
13th Jul 2019, 5:05 pm | #16 |
Triode
Join Date: Jul 2019
Location: Harwich, Essex, UK.
Posts: 39
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Re: AM FM alignment
Thanks again guys I have requested prices from two companies for the Phillips. What do you think of this HP ending tomorrow on ebay. Looks like it would need an external modulator? https://www.ebay.co.uk/itm/HP-8165A-...AAAOSwAz1dD~pk
Also remember I am very new to this and learning more everyday. I would like to purchase equipment that I can grow into as I progress in my knowledge and understanding. |
13th Jul 2019, 5:08 pm | #17 | |
Octode
Join Date: May 2016
Location: Oxfordshire/Bucks borders, UK.
Posts: 1,604
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Re: AM FM alignment
Quote:
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Avometer, vintage Fluke and Marconi collector. Also interested in vintage Yaesu and KW. |
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13th Jul 2019, 5:40 pm | #18 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: AM FM alignment
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13th Jul 2019, 6:06 pm | #19 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,783
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Re: AM FM alignment
I agree with Lawrence, this sort of kit is OTT for ordinary vintage radio work.
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13th Jul 2019, 6:11 pm | #20 | |
No Longer a Member
Join Date: Oct 2016
Location: Maroochydore, Queensland, Australia.
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Re: AM FM alignment
Quote:
The PM5324 is a much bulkier unit and lacks the digital frequency meter which is one of the great advantages of the 5326, making it super easy to use and better than any generator with an analog dial. Though of course you could add a frequency counter to any analog dial generator, but it is more kit and won't be as compact and elegant as the 5326.Once I used the PM5326, I never went back to an analog dial generator, though there were some beautifully made ones out there. |
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