[600MRG] Some experimenting with toroids vs hollow coils on 630m

Thu Feb 16 12:36:37 EST 2023

Wow!  The perm. of the 52 is 265 @ 500K, that of 77 is 2142.  It's like using mud there and you do need way more turns with the loss.  More turns is more wire loss so no wonder the SWR gets faked is using at the antenna base.
Now, interesting is that the 77 has u' of 2142 while u" is 250  while the 52 has u' of 265 while the u" is 2.74, a way smaller ratio.  There must be a situation where, say for filtering, that that lower loss is an advantage.  Any expert on this want to shed a little light?
N0UU

> On February 16, 2023 at 12:53 AM "Brian Justin, WA1ZMS" <wa1zms at att.net> wrote:
> 
> 
> .
> I think you will find that #77 material will be the best ferrite for 630m.   I have used the relatively new #52 material for full HF (160m thru 10m) and it’s better than the much old-school #43.
> 
> 
> 
> -Brian, WA1ZMS
> iPhone
> 
> > On Feb 15, 2023, at 22:23, D.J.J. Ring, Jr. <n1ea at arrl.net> wrote:
> > 
> > This is what you found better:
> > 
> > https://www.ebay.com/itm/153981039085
> > 
> > Have you tried any of the other core materials. I'm guessing that the
> > FT240 is the heaviest duty torroid they make and what's after the
> > hyphen is the core material.
> > 
> > I see others but all are less expensive, but you probably went first
> > class and for 10 dB it sure is worth it.
> > 
> > 73
> > DR
> > 
> >> On Wed, Feb 15, 2023 at 9:51 PM Neil Klagge <w0yse at msn.com> wrote:
> >> 
> >> The following is just my experience, not a scientific thesis  😉
> >> 
> >> These are the results of an experiment comparing a FT240-52 with a hollow cylindrical coil on the ouput of my 630m IRF510 FET power amplifier for 630m.
> >> 
> >> Transmitter output was 4.5w input to the toroid for this test, but there was only 2w left on the output of the toroid, going into the coax to the antenna. The KA7OEI-1 Northern Utah SDR was used during midday to decode my signal with that core. The results were worse by about 10 dB compared to when using the hollow PVC coil. The amplifier ran very warm with the toroid even though my fans were running full blast and even though the SWR was very low.
> >> 
> >> Using the same output power of the amplifier, the cylindrical coil got a 10 dB stronger report from the SDR.  And, there was negligible heating of the amplifier.   (I had similar results with an FT240-43 core the previous week).
> >> 
> >> The #52 core is less than 45% efficient whereas the PVC coil is about 83% efficient. The PVC coil wins!
> >> 
> >> 
> >> 
> >> Next, I experimented with the 52 core at the base of the antenna. I was able to get the SWR under 2.0 at the base of the antenna by adding or subtracting turns on the core. Inside the shack I could adjust the SWR to about 1.2 but the amplifier still ran hot when using the toroid and the reports back from the N. Utah SDR were weaker by about 7 dB.
> >> 
> >> My original coil at the base of the antenna works much better than the 52 core.
> >> 
> >> Hoping some will find this useful...
> >> 
> >> 73
> >> 
> >> *´¨)
> >> ¸.•´¸.•*´¨) ¸.•*¨)
> >> (¸.•´ (¸.•`   Neil , wØyse, DN41ah, North Ogden, Utah 84414
> >> 
> >> 
> >> My ham radio website: http://w0yse.webs.com/
> >> 
> >> My Faith website: http://neilsfaith.webs.com/
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