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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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2nd Jan 2024, 7:52 pm | #1 |
Diode
Join Date: Jan 2024
Location: Cheltenham, Gloucestershire, UK.
Posts: 3
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First Restoration/Refurb Bush VHF 41
Hi all going to do my first ever restoration of a Bush VHF 41 that I have had for some time.
I used to be an electronics techy but it has been a few years (10 plus) since I have done any electronics. So for background I know the Bush has little value and I intend to use it to get back into electronic repair. The radio was used occasionally until about three years ago and worked OK but hummed a bit. So my plan is crack it open and see what it is like inside and start checking the mains cable and the Caps etc for damage. I also plan to make a bulb current limiter before any thoughts of switching it on. So the question is replace the usual suspect caps or invest in a Peak ESR tester and hints and tips welome. |
2nd Jan 2024, 8:05 pm | #2 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,783
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Re: First Restoration/Refurb Bush VHF 41
If I were you I wouldn't buy expensive specialist test gear at this stage. Just replace the Mouldseal caps (which are probably disintegrating anyway), reform the smoothing electrolytics or replace them as necessary, then power up on a lamp limiter.
The Chinese component analysers you can buy for about £15 are a worthwhile complement to your DMM. They measure ESR quite well. |
2nd Jan 2024, 8:19 pm | #3 |
Diode
Join Date: Jan 2024
Location: Cheltenham, Gloucestershire, UK.
Posts: 3
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Re: First Restoration/Refurb Bush VHF 41
Thanks for that I have a decent DMM and will probably replace the caps and not reform unless they still look nice.
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2nd Jan 2024, 8:35 pm | #4 |
Nonode
Join Date: Nov 2016
Location: Aberaeron, Ceredigion, Wales, UK.
Posts: 2,869
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Re: First Restoration/Refurb Bush VHF 41
If you have not already done so I would definitely get the circuit diagram to familiarise yourself with layout etc.
John |
2nd Jan 2024, 8:36 pm | #5 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 13,951
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Re: First Restoration/Refurb Bush VHF 41
Welcome to the forums! We're a friendly bunch.
The VHF41 is a good receiver on which to cut your teeth. Unlike later Bush VHFxx models it doesn't have a potentially-live chassis so is less likely to kill you; it's got easily-sourceable valves if you discover those in the VHF front-end have got a bit tired, and given that it covers VHF [though not all the way up the band] there will be interesting stations to listen to [unlike MW/LW-only radios from the era]. Replace the Hunts/Mouldseals type capacitors as a first step; then warm it up slowly [some people use lamp-limiters; I just give a radio some 5-minute bursts of full mains with a 5-minute recovery period in between], hook it up to a decent FM antenna, then see what you can hear!
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2nd Jan 2024, 8:37 pm | #6 |
Heptode
Join Date: Mar 2017
Location: Romsey, Hampshire, UK.
Posts: 511
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Re: First Restoration/Refurb Bush VHF 41
Hi
The VHF41 was an early set for FM, when manufacturers were still finding their way. If the valves are a bit 'tired' (low emission), performance will be degraded. Also, it will need a decent strength FM signal, so an outdoor dipole would be best if you can manage it. This thread might be of interest: https://www.vintage-radio.net/forum/...d.php?t=155847 When changing caps, unless you are experienced I suggest doing one at a time and checking in between. Any resistor over 100K should be checked for value on the ohms range of a testmeter, you'll generally need to lift one end to isolate it from the circuit before doing this. |
3rd Jan 2024, 10:45 am | #7 | |
Dekatron
Join Date: Dec 2004
Location: East Yorkshire, UK.
Posts: 3,957
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Re: First Restoration/Refurb Bush VHF 41
Quote:
Good advice MR 1936, Also when changing capacitors I do not try to untangle the wire, I cut the capacitor out leaving long wires, this identifies which are the two contact you are working on. ( you only need one wire on the wrong tag and if you have not tried set after each cap change it will become a real problem to solve) Then try and push the tinned wire of the cap through though the hole in the tag while heating, if not possible you can clean the old wire you left and attach it there. The solder tags on most valve bases are especially delicate use no force on them. Any long wires should be tided up once that connection is working ok. Also adding extra flux helps a lot when trying to solder to old wires. BTW, The circuit is available top right of this page in red for £1.99, please let us know which of the three sheets you are using. John.
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3rd Jan 2024, 11:30 am | #8 |
Octode
Join Date: Nov 2005
Location: Surrey, UK.
Posts: 1,869
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Re: First Restoration/Refurb Bush VHF 41
Well built sets, but not the best performer on FM. The EF80s in the front end need to be good, and the alignment on FM may need small adjustments, especially to the ratio detector transformer. Remember that the FM IF frequency is non standard - 19.5 MHz I think.
The BEC main smoothing capacitor will be fine - just reform it slowly. The ratio detector stabilising capacitor will require renewal as it is small and dries out. Unlike the later Bush AM/FM sets, this one works very well on AM, having a properly designed front end. Mine was only marginally stable on AM, having excessive IF gain due to the high slope EF85. I fitted damping resistors to the AM IF transformers which sucessfully tamed it. A really nice set to work on - have fun. Leon. |
3rd Jan 2024, 2:08 pm | #9 |
Octode
Join Date: Sep 2020
Location: Thetford, Norfolk, UK.
Posts: 1,731
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Re: First Restoration/Refurb Bush VHF 41
Welcome to the forum.
Once you have carried out what others have already said, note that if you have poor or no AM performance but VHF is OK, then it is likely to have a tired ECH81 valve; readily available and inexpensive. Also, distortion on FM on an otherwise good set is often a tired, unbalanced EABC80 valve. |
3rd Jan 2024, 6:40 pm | #10 |
Diode
Join Date: Jan 2024
Location: Cheltenham, Gloucestershire, UK.
Posts: 3
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Re: First Restoration/Refurb Bush VHF 41
Hi thanks for the advice I have the 14 page manufacturers data sheet. Good advice on the valve bases as I imagine they are very brittle now.
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