I.F. Alignment
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Location: Mildura, VIC
Member since 5 May 2011
Member #: 896
Postcount: 108
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Is there any Procedure on how to align old radio's, I know the signal has to be 455 KC or there abouts, but is each make of radio different?
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5389
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The signal may not be 455kHz eg HMV Nippers are not for one.
Getting that wrong will seriously impinge on the way the set performs.
Many of the vintage radio sites have procedures, but they can vary with manufacturer. The circuit of the set will normally have the IF frequency on it.
Astor is one that often had that info and procedure on the sheets, many of which appear In AORSM's.
If you feel like a trip to Sheparton on the 28th. IF alignment is the Vintage Radio Clubs Demonstration & Topic for the meeting.
Marc
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Location: Melbourne, VIC
Member since 5 October 2009
Member #: 555
Postcount: 466
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Larry,
Sounds like I have been down the same path as you recently.
There is no 'one technique' for aligning the IF (eg depends on how you measure the 'alignment', where you inject the IF frequency, AGC circuitry, number of IF stages etc), HOWEVER, the basic principles are the same for all old radios.
If you cannot find the procedure relevant to your particular radio, study the procedure for several different radios and understand the principles and the reasons for the differences. Then all you need, as Marc says, is the correct IF frequency.
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Cheers,
Ian
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Administrator
Location: Naremburn, NSW
Member since 15 November 2005
Member #: 1
Postcount: 7395
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It's ironic that a modern digital radio's tuned circuit and amplifier is all embeded in a chip on a printed circuit board and requires no alignment at all yet will only last a few years whilst radios that are between 50 and 90 years old require tweaking every ten years or so and will theoretically survive for hundreds of years if looked after.
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A valve a day keeps the transistor away...
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Location: Wangaratta, VIC
Member since 21 February 2009
Member #: 438
Postcount: 5389
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You would be amazed at how many of the old dears have not moved frequency. Some have badly designed coils where glue breaks or windings sag.
One of the greatest enemys of IF's, or anything in a radio, really, with adjusting screws. The Monkey will want to fiddle with them if the set has problems.
One would like to think we have made advances in radio. Many of those modern things have crystal filters that are unajustable & amazingly stable.
Marc
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Administrator
Location: Naremburn, NSW
Member since 15 November 2005
Member #: 1
Postcount: 7395
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Some have badly designed coils where glue breaks or windings sag.
Yep, seen plenty that have been dipped in wax only for the wax to shrink and dry out which either ruptures the winding or exposes it to the air and lets the windings turn green and/or leeching copper sulphate ooze. Great stuff to get on your fingers just before lunch.
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A valve a day keeps the transistor away...
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Location: Mildura, VIC
Member since 5 May 2011
Member #: 896
Postcount: 108
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My 2 radios, seem to be fine, Alignment wise, just the dial is a little off, I just wanted to know if the procedure was similar with most, but thanks anyway
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Location: Melbourne, VIC
Member since 5 October 2009
Member #: 555
Postcount: 466
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Larry,
"....just the dial is a little off," this suggests that your RF tuning needs alignment with the radio dial ...... not an IF alignment issue. But be aware, if you change the RF tuning, you will also need to re-align the oscillator so that the RF and oscillator frequency difference equals the IF.
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Cheers,
Ian
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Location: NSW
Member since 10 June 2010
Member #: 681
Postcount: 1301
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I have a Receiver Alignment article from the early seventies (EA Home Studies Course) that covers manual methods of receiver alignment for superhet radios (aerial, RF, IF and dial).
A bit long winded (four pages), but thorough. TRF radios also covered.
Also a brief introduction to alignment with a signal generator.
If anyone is interested, post a request and open up your email and I well send a pdf.
The article seems to say that the IF frequency is not super critical, and that a few kHz out does not matter as long as the IF stages are all the same.
IF alignment is done by peaking the volume by ear on a weak station at the low frequency end of the dial. As the volume improves with alignment a weaker station is used or the aerial shortened or even removed. Sounds rough but I have used it and got good results. If you have no instruments it is better than nothing.
A wrinkle is that AM bandwidth was reduced to 9kHz when AM stereo was introduced in the '80s, and many stations were slightly shifted on the dial. So many stations no longer tune to the dial marking on pre '80's radios. It is necessary to look up the actual station frequency and use the frequency scale on the dial (if it has one) when aligning the aerial and, if it has one, the RF section.
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Location: NSW
Member since 10 June 2010
Member #: 681
Postcount: 1301
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This book on the net (different from above)
The Vacuum Tube Shortwave Radio, Understanding and Troubleshooting by Richard McWhorter http://www.richardmcwhorter.com/vacuumtuberadio/ has a detailed section on alignment with instruments.
It is pdf file and is free.
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Location: Blue Mountains, NSW
Member since 30 June 2011
Member #: 944
Postcount: 30
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Location: Melbourne, VIC
Member since 5 October 2009
Member #: 555
Postcount: 466
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STC380,
I have been away for several weeks and only now starting to catch up with some of these Threads. I would like to take you up on the offer of sending the IF Alignment pdf. My email should be visible.
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Cheers,
Ian
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Location: NSW
Member since 10 June 2010
Member #: 681
Postcount: 1301
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Should be in your inbox now.
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Location: Melbourne, VIC
Member since 5 October 2009
Member #: 555
Postcount: 466
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Got them both. Thanks STC830
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Cheers,
Ian
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Location: Blue Mountains, NSW
Member since 30 June 2011
Member #: 944
Postcount: 30
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