pete
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Post by pete on Jul 5, 2021 11:46:44 GMT 12
Steve
The weather is not that flash today. I do not think I will get much done.
Sticking to the theme of doing what I can, when I can, I have had a go at establishing whether there is worthwile AM transmissions around. I used a decent small portable transisitor radio, aided by a 3m long antenna I hung out of the window.
I managed to get two or three decent signals. I tried to tune in to Timaru National Radio (supposedly on 918) without much success. There are a few others though (no idea where they may be broadcasting from). This means that I should be able to pick up something if/when I get the Gulbransen going.
I am working through the videos you suggested, to see what I can learn from them.
Question: My old valve radio (used last in 1975) was equipped with a ground wire and antenna. I knew which was which and used them appropriately. There is one black and one white wire eminating from the antenna coil on the Gulbransen. Any idea which is which ?
Remark: I am disgusted by the radio interference produced by modern households. I have traced a terrible hum (on AM) back to the LED lights (most likely their power units) which had been installed in our house. I guess nobody cares about keeping the AM band clean nowadays.
Regards. Pete
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Post by Peter Walsham on Jul 5, 2021 12:30:53 GMT 12
LED Light interference:
I fitted LED lamps to all of my light fittings in my own home, and was totally dismayed by the levels of radio frequency interference they caused on the AM band. I got the lamps from 'Lighting Plus', and I wrote an email to them about this - as I was pretty certain that electronic equipment imported to NZ had to be RFI compliant. The response from 'Lighting Plus' was not very helpful (actually next to totally unhelpful), and centred around the lamps being electrically safe & compliant (with the supporting relevant documentation of conformity (SDOC) to verify), but there was nothing mentioned about radio interference. I have a Remington cordless shaver - and the charger for that swamps the AM band with interference, as does my Fibre 'ONT' (the 'box' screwed to the wall) and the modem. A couple of laptop power packs/chargers also create interference as well. These all contain Switch Mode power supplies that generate broad band interference with their harmonics. Switch mode power supplies are a bloody menace! GRRRRRRR!!!!!!!!!!!
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Steve
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Post by Steve on Jul 5, 2021 13:29:07 GMT 12
Yep, RFI is a huge problem. My solution is to use incandescent bulbs on my service bench, along with LED strip run from transformers and linear regulators. The workbench itself is in the garage, well away from other electronics and the circuit feeding the garage has nothing else on it. The worst offenders in my house are the two 15W light panels in the shelf over my coffee machine - they were cheapies off Ali Express so I am ok with that - I turn them off when I'm doing radio stuff.
I've definitely found the cheap LED bayonet or Edison-screw bulbs are worse - Philips ones seem quieter. But even good LED bulbs seem to have a shortish life out here in the country so paying more for them gets painful.
I've yet to find a way to get around it short of switching everything else off.
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Steve
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Post by Steve on Jul 5, 2021 13:33:33 GMT 12
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pete
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Post by pete on Jul 5, 2021 17:57:32 GMT 12
Steve Thanks for the list of radio stations. When I get my grubby little paws on a decent AM radio (preferably with digital read-out) I will try to decipher the origin of the radio signals I am able to pick up here in Ashwick Flat.
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pete
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Post by pete on Jul 6, 2021 16:30:01 GMT 12
Hi guys.
Any ideas on the distinction between the ground and antenna wires as mentioned above ?
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Steve
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Post by Steve on Jul 6, 2021 23:54:01 GMT 12
Hi Pete, white is probably the aerial, but one will be connected to the chassis so trace the wires from the aerial coil and see which one is tied to ground. Or just check the resistance of each wire to the chassis. Lowest resistance will be earth.
Cheers, Steve
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pete
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Post by pete on Jul 7, 2021 9:08:36 GMT 12
Steve.
Thanks. I will sort this out ASAP. The weather is once again lousy. I will attempt to clean out an area in the garage where I can work on the radio.
Cheers. Pete.
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pete
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Post by pete on Jul 12, 2021 13:51:12 GMT 12
Hi guys
I have run into a few logistical problems and will not be able to advance the project within the next few days. I will let you know once I get going again.
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Steve
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Post by Steve on Jul 12, 2021 14:42:56 GMT 12
No stress Pete - vintage radio repairs are a long game, not a race
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pete
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Post by pete on Jul 14, 2021 11:42:43 GMT 12
Hi guys
My closest supply of electronic components is in Timaru. There is a agent for Jaycar located in the CBD. I spoke to the owner yesterday. He advised me that he will not be able to supply me with much in terms of a valve radio restoration. I may be able to get the odd pot, resistor or length of wire from him, but he does not stock, and can not readily get, high voltage value caps, valves etc. It seems I will have to scour the treasure troves of NZVRS's members once I get to that point in the project ! Until such time as I have sorted a proper workplace and a decent storage area for this project, I will be restricted to superficial restoration work (cleaning stuff, polishing dull metal etc.)I know not to take stuff apart if I am not able to properly document the process, store individual components securely and stop work (without having to move stuff around)at any time. Still very keen, just hamstrung - very frustrating ! Regards. Pete.
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Steve
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Post by Steve on Jul 14, 2021 18:37:07 GMT 12
Hi Pete, most of the parts you will likely need are available, through the NZVRS, to members - you can join here: nzvrs.com/membership-form/It's ridiculously cheap, and well worth it. And yep, I can confirm from experience, keep it whole until you're ready to pull it apart and put it back together again. Cheers, Steve
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Post by Peter Walsham on Jul 15, 2021 11:10:46 GMT 12
Jaycar do stock 630 Volt polyester capacitors in the common values and at reasonable prices - however, the NZVRS caps are axial and more 'authentic' than the PCB ones that Jaycar sell.
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Steve
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Post by Steve on Jul 15, 2021 17:26:53 GMT 12
There are Jaycar stores, and there are Jaycar agents. The agents don't always stock everything the full stores do... So it's possible your local agent won't have marginal lines like 630v caps. They probably do have 1 or 2W resistors though, they sell them in cards of 2 and they are brown carbon ones that look far less out of place than blue metal film ones.
Cheers, Steve
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Post by Peter Walsham on Jul 15, 2021 18:00:46 GMT 12
You're dead right Steve. My local 'Jaycar' store is only a Jaycar 'stockist'. Recently, when I wanted to buy a 5" speaker, they didn't have one in stock (nor did the Jaycar online order store). Manukau is the nearest 'genuine' Jaycar store, and they had several of these in stock, but Jaycar evidently have a policy that they don't (can't & won't) do stock transfers between stores, nor do individual stores ship stock in any form. Also, I learnt that Jaycar's stocking policy is: If stock is on its way from Australia, the 'genuine' Jaycar stores get stock priority over the 'stockist' stores, so I was unable to buy this speaker from the Pukekohe store at all. I was not at all amused!
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