Hi Allison, yes the small binocular core must be a material similar if not 43, which for the low bands such as 160 and 80m has its use. What happens to the self resonant frequency? Is RF all converted into heat? May it be dangerous to transmit in there?

Make sure you not in transmit mode!
Check the switched 12V line to see if its 12V-T or 12V-R

Two most common problems is forgot the resistor for the key (4.7K) so its in CW tx mode.
And the TX (transmit line, orange) is grounded due to wrong pin on mic socket or even mic plus.
Allison

Iz

VSWR measurements as a means of evaluating the performance of wide band transformers are almost meaningless. In order for the VSWR to mean anything one must first know how much power is actually being transformed versus how much power is being turned in to heat by transformer losses. A transformer with 100% loss will show an SWR of 1:1. A 49:1 transformer with no loss, perfectly terminated in a 2450 ohm resistive load will also show a VSWR of 1:1. A transformer with 90% loss, terminated with a 10:1 mismatch, will show a VSWR of very nearly 1:1.

The only effective way to measure the performance of an impedance ratio transformer is to build 2 and place them back to back and measure how much power gets through.

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WA8TOD

This is from my friend Konstantinos SV1ONW please open it with LibreOffice Writer .

Hi in izq Danilo, the 2822 was used up to ver. 3. Then as the failure rate was high it had been replaced by a different circuit. The 2822 by the way was able to produce a pretty loud volume. In your case check whether the volume pot was properly wired.

I would like to share with you the results from two different experimental 1:49 transformers I made. First one is low power made with just a small binocular ferrite. Primary has just 2 turns and 8.8uh, secondary 14 turns 413 uH. 150pf across the primary . I don't know the material but I see not measurable SWR without termination. Terminating with a 2500ohm resistor i find an SWR close to 1.2 on 160m dipping on 80m and rising up to 1.80 on 40m. Beyond 40m swr is higher. The other transformer is made with a T200-7 (white, iron powdered toroid). Primary and secondary dc isolated, 90 turns (about 90uh) on the secondary and 12 turns spread over the primary over 200 degrees (about 2 uh) . Primary and secondary windings are made with enameled wire and there is a layer of transformer tape between the secondary and the primary. There is no fancy winding (no change of winding direction) just primary over the secondary. 120pf across the primary. Without termination I got infinite swr below 20Mhz. The secondary is 7 meters long and SWR is very low on 20.8mhz. Terminating with a 2500ohm resistor SWR is descending to something more than 2 on 80m, 1.3 on 40m and 1 or very close to 1 on 30m, 20m and 17m. Using a 360pf variable instead of the fixed cap the SWR drops on 80 to 1.67 and close to 1 from 40 to 17m band. As said to make a proper test I should do a back to back test but it seems to me now that both transformers may work reasonably well, the small ferrite transformer on low bands and the iron powdered cores one well from 80 to 17m bands. So, even if the material of the cores were likely not to be the proper ones, it seems they may be used for building high transformation ratio conventional transformers, albeit not extremely wideband.

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