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90volt battery by upconversion from 9volt
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Return to top of page · Post #: 1 · Written at 8:59:09 PM on 12 October 2013.
	Maven Location: Canberra, ACT Member since 23 August 2012 Member #: 1208 Postcount: 584
Now that I have a working AC/DC portable, I am interested in making a 90volt battery substitute. There's an article reprinted from the HRSA at http://www.portabletubes.co.uk/sitefiles/ausbatt.htm that describes construction of a solid-state device to deliver 67-90volts suitable for a radio B battery, powered by a 9volt battery. It looks to be within my capability to build, and if so I would be able to power my portable from 9v rechargeable batteries A and B, when not on AC. The author was a Tony Maher of Melbourne, and the date was 2001. At that time, apparently a PCB was available. Does anyone have experience or knowledge of this particular device or others like it? Maven

Return to top of page · Post #: 2 · Written at 8:04:48 AM on 13 October 2013.
	Redxm Location: Tamworth, NSW Member since 6 April 2012 Member #: 1126 Postcount: 466
I have built 2 of these. 67v & 90v. The 67v version fits nicely into an old battery case. Pay the extra few dollars and get the auto start version. I have heard that they produce a bit of rfi, I havent noticed it myself, but my local am station is very close. If you were trying to pick up distant stations it may be an issue. Over all a very nice solution. Ben

Return to top of page · Post #: 3 · Written at 8:17:20 AM on 13 October 2013.
	GTC Location: Sydney, NSW Member since 28 January 2011 Member #: 823 Postcount: 6686
The author was a Tony Maher of Melbourne, and the date was 2001. At that time, apparently a PCB was available. I think Tony, who is currently President of the HRSA, sells these made up. You can contact him at tmaherdetedtion.com.au

Return to top of page · Post #: 4 · Written at 12:10:55 PM on 13 October 2013.
	Gandhn Location: Cameron Park, NSW Member since 5 November 2010 Member #: 770 Postcount: 387
I have also built the 67V version, before the auto start model came out. As Ben commented above, it fits into the old Mini-max battery size so if you wanted it to look right as well as being functional, it is a good solution. I would go the auto start way if I were to get another. Harold

Return to top of page · Post #: 5 · Written at 4:08:33 PM on 13 October 2013.
	Redxm Location: Tamworth, NSW Member since 6 April 2012 Member #: 1126 Postcount: 466
A couple of pics of my 90v & 67.5v converters. Apologies in advance for bad photos. Ben

Return to top of page · Post #: 6 · Written at 5:16:28 PM on 13 October 2013.
	Maven Location: Canberra, ACT Member since 23 August 2012 Member #: 1208 Postcount: 584
Yes, it would be nice to be able to cover it with a facsimile of an appropriate battery cover. I like the jumping cat. In my radio, this will be about 1cm from the loop antenna in the rear flap of the case. If there is any RFI problem from the oscillator circuit, maybe an aluminium foil shield between device and antenna could help? One of yours looks like it has some sort of foil lining in the box? Maven

Return to top of page · Post #: 7 · Written at 8:38:43 PM on 13 October 2013.
	Redxm Location: Tamworth, NSW Member since 6 April 2012 Member #: 1126 Postcount: 466
Harold Contact Tony. He has a mod available to retro fit for auto start. Maven. I use the 67v one in a HMV p17 personal portable with no issue. However, as I mentioned I'm very close to the radio station. There is no foil in the battery box, its a reflection. Ben

Return to top of page · Post #: 8 · Written at 11:55:13 AM on 22 October 2013.
	Maven Location: Canberra, ACT Member since 23 August 2012 Member #: 1208 Postcount: 584
I tried emailing Tony Maher (tmaherdetection.com.au) but didn't get any response. Does he only respond to HRSA members? Any other ideas on how to contact or get hold of PCB or other construction advice? Maven

Return to top of page · Post #: 9 · Written at 11:59:30 AM on 22 October 2013.
	GTC Location: Sydney, NSW Member since 28 January 2011 Member #: 823 Postcount: 6686
Does he only respond to HRSA members? I doubt it. He may be on holiday, or indisposed for some other reason. Try calling him on (03) 9800 4895 (evenings and weekends)

Return to top of page · Post #: 10 · Written at 11:41:17 AM on 23 October 2013.
	Art Location: Somewhere, USA Member since 22 October 2013 Member #: 1437 Postcount: 896
Did some things like this a while back, not really for radio at the time: Image Link Image Link You can get beat up on some forums making things like this without good reason. This kind of thing usually works with pulse width modulation (ie. the output is a square wave). It's not for me to say if this is good for a valve radio or not, but explains potential interference produced by them, doing high speed switching.

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