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Old 11th Sep 2021, 1:31 pm   #1
pentoad
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Default Taylor 68 resistors

Some of the resistors on the oscillator circuit connected to the coils are out of tolerance, some widely out.
Should I avoid metal or carbon film as these may be spiral cut and therefore inductive?
I would like to use carbon comp but some of the values are not available, are the ones described as metal oxide (not MF) okay as a substitute or is metal oxide used in metal film type, so the term can be misleading?
I believe that metal oxide resistors are formed in a continous solid in the way carbon composite are, but there is no way of differentiating between types if the vendor has got it wrong.
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Old 11th Sep 2021, 3:16 pm   #2
pentoad
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Default Re: Taylor 68 resistors

I have just found Hifi Collective have a good range of Arcol carbon comp resistors so I will use those.
But I would still be interested in having the question answered if possible.

Last edited by pentoad; 11th Sep 2021 at 3:34 pm.
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Old 11th Sep 2021, 4:09 pm   #3
Chris55000
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Default Re: Taylor 68 resistors

Hi!

Both metal–film and (some types of) metal–oxide resistors have a spiral–cut element/track, so if you want to be sure of not adding unforseen inductance to the h.f. ranges of your Taylor Generator, then you need to replace the resistors in the r.f. oscillator with the solid carbon–composition type, preferably the same wattage as those originally fitted, as the generator would have been originally aligned in Taylor's factory with the appropriate resistors specified in their parts list – for example, if you replaced a ¼W carbon composition resistor with a ½W one, the stray–capacitances to earth and to other components would differ from when the generator was first built and aligned!

However, if you have an accurate counter, and you're very careful about choosing & fitting the replacement resistors, you shouldn't find the alignment of the generator is too far out!

Chris Williams
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Old 11th Sep 2021, 4:59 pm   #4
Marconi_MPT4
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Default Re: Taylor 68 resistors

Hi,
Frequency tracking and alignment on higher ranges may be affected when using metal film replacements, but this largely depends on resistor value as shown in the Welwyn MFR4, PR4 and RC55 HF |Z|/Rdc performance graph here:

https://www.vintage-radio.net/forum/...2&postcount=17

Rich
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Old 11th Sep 2021, 5:03 pm   #5
pentoad
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Default Re: Taylor 68 resistors

Quote:
Originally Posted by Chris55000 View Post
Hi!

Both metal–film and (some types of) metal–oxide resistors have a spiral–cut element/track, so if you want to be sure of not adding unforseen inductance to the h.f. ranges of your Taylor Generator, then you need to replace the resistors in the r.f. oscillator with the solid carbon–composition type, preferably the same wattage as those originally fitted, as the generator would have been originally aligned in Taylor's factory with the appropriate resistors specified in their parts list – for example, if you replaced a ¼W carbon composition resistor with a ½W one, the stray–capacitances to earth and to other components would differ from when the generator was first built and aligned!

However, if you have an accurate counter, and you're very careful about choosing & fitting the replacement resistors, you shouldn't find the alignment of the generator is too far out!

Chris Williams
Great advice - thank you
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