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Old 1st Jun 2020, 5:19 pm   #1
eddie_ce
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Default Advice: Ultra T401 IFTs

Hi all,
I am in the process of restoring an Ultra T401. Unfortunately the brass tuning slugs on the IFTs are completely seized up.

The brass seems to be quite soft, so any force is out of the question. What is the best method of freeing the brass slugs?

There is a threaded screw (approx. 3.8mm) with a slot for adjustment, does this part screw into the brass cylinder (approx. 6mm in diameter) going into the IFT or are the threaded part and the cylinder one part?

I hope you can make sense of this description.

Thanks for any help.
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Old 1st Jun 2020, 5:31 pm   #2
G6Tanuki
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Default Re: Advice: Ultra T401 IFTs

I'm not totally familiar with the radio in question, but I would suspect that the "brass cylinder" you see is actually a threaded insert fitted into the Bakelite/phenolic coil-former, and on the other (non-slotted) end of the threaded rod will be a ferrite or powdered-iron core.

The issue being to free the threaded rod from the thread in the 'cylinder'. I'd suggest initially trying a _very_ small amount of something like "Plus Gas" releasing-fluid, applied to the point where the threaded rod goes into the threaded cylinder using something like a toothpick.
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Old 1st Jun 2020, 5:44 pm   #3
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Default Re: Advice: Ultra T401 IFTs

Photo?
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Old 1st Jun 2020, 6:16 pm   #4
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Default Re: Advice: Ultra T401 IFTs

I faced the exact same problem two days ago, on a T401 i'm looking at.

I made the mistake of trying to hard and broke the brass! so don't do it. Instead try this HEAT THEM UP with a soldering iron it softens the varnish and you can then turn them, i suggest start by screwing then in a little then unscrew etc. Take it steady - and yes you have to get them quite hot!

Derek

ps the one i broke have enough space to use a jnr hacksaw to re-grove the top.
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Old 2nd Jun 2020, 4:14 pm   #5
eddie_ce
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Default Re: Advice: Ultra T401 IFTs

Derek,
I made exactly the same mistake on one of the brass screws. Luckily with the help of a Dremel I was able to deepen the slot sufficiently to allow adjustment.

With a lot of patience and a mixture of PlusGas and Isopropanol in a hypodermic syringe I managed to free all 4 slugs.

A tip: I found that a 4mm nut fits over the screw thread, I screwed this far enough down so that the top of the nut was flush with the top of the brass screw, this enables adjustment with slightly more force without having to worry about sides of the slot splaying out and snapping off. It also provides a guide for the screwdriver blade.
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Old 2nd Jun 2020, 5:32 pm   #6
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Default Re: Advice: Ultra T401 IFTs

Was the alignment far off? I must admit it is rare to find these old receivers that require realignment. If the cores are 'safe' I tend to check the I.F. alignment but very rarely find them off tune. Just a thought as it is so easy to damage cores and I.F. transformers. John.
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Old 2nd Jun 2020, 5:56 pm   #7
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Default Re: Advice: Ultra T401 IFTs

Hi john, On the one I looked at it was out - not by much. But i find this radio a bit lacking in sensitivity anyway so any improvement was worth it.
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Old 2nd Jun 2020, 6:04 pm   #8
eddie_ce
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Default Re: Advice: Ultra T401 IFTs

Hi John,
I plan to check the alignment tomorrow. However, even if it is not too far off, I like to be able to set things up as best as possible. Perhaps, because of the risk of damage it really is better to stick to the adage "if it's not broken ....".

Mods, I think this could be closed. Thank you for your replies.
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