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The HG-2SC2312 have arrived.

[ATTACH=full]63756[/ATTACH]

[ATTACH=full]63757[/ATTACH]

hFE of 47 and 51, quite well matched.

@ [USER=10801]DoctorAudio[/USER]: it was a good tip to get these. I replaced both finals and set the bias to 40mA for each (50mA for the driver TR43 according to the manual). I re-did the Tx alignment and now the amplitudes of the RF signals are ok .

For the AM carrier unmodulated, I have limited the RF output voltage (measured with the oscilloscope on the dummy load) to 65V p-p, corresonding to 10W, right on spec.
In AM with 100% modulation the excursion is nearly 120V p-p, corresonding to 35W PEP - wow!

[ATTACH=full]63758[/ATTACH]

In SSB, with the 2-tone signal on the mic, I get 86V p-p max excursion, corresponding to 18W PEP, slightly short of the 21W in the specs for this kit.

[ATTACH=full]63759[/ATTACH]

I guess this is good enough, but there is still one thing that puzzles me. Why do I get a much higher voltage excursion in RF output for AM than for SSB? In AM I can go even higher than 120V p-p (with 100% modulation) if I turn up the AM carrier power (VR-13). But in SSB I cannot go higher than 86V p-p.

I measured the amplitude at the base of the driver (TR43):
- in AM Tx: 9V p-p
- in SSB Tx: 1.8V p-p

So the signal at the base of the driver is a lot smaller in SSB. I guess this must be the reason, even if in SSB the finals work in class AB, with the full 13.8V DC applied at the collectors.

I should say that I tweaked very carefully the coils upstream of the RF amplifier (L45, L46, L48 and L49) in SSB for max output, so it must be something else...

Any suggestion is welcome!

<blockquote data-quote="Summertown" data-source="post: 816290" data-attributes="member: 65077">The HG-2SC2312 have arrived.[ATTACH=full]63756[/ATTACH][ATTACH=full]63757[/ATTACH]hFE of 47 and 51, quite well matched.@ [USER=10801]DoctorAudio[/USER]: it was a good tip to get these<img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f44d.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt="(y)" title="Thumbs Up&nbsp; &nbsp; (y)"&nbsp; data-smilie="27"data-shortname="(y)" />.&nbsp; I replaced both finals and set the bias to 40mA for each (50mA for the driver TR43 according to the manual). I re-did the Tx alignment and now the amplitudes of the RF signals are ok <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f60e.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":cool:" title="Cool&nbsp; &nbsp; :cool:"&nbsp; data-smilie="6"data-shortname=":cool:" />.For the AM carrier unmodulated, I have limited the RF output voltage (measured with the oscilloscope on the dummy load) to 65V p-p, corresonding to 10W, right on spec.In AM with 100% modulation the excursion is nearly 120V p-p, corresonding to 35W PEP - wow![ATTACH=full]63758[/ATTACH]In SSB, with the 2-tone signal on the mic, I get 86V p-p max excursion, corresponding to 18W PEP, slightly short of the 21W in the specs for this kit.[ATTACH=full]63759[/ATTACH]I guess this is good enough, but there is still one thing that puzzles me. Why do I get a much higher voltage excursion in RF output for AM than for SSB? In AM I can go even higher than 120V p-p (with 100% modulation) if I turn up the AM carrier power (VR-13). But in SSB I cannot go higher than 86V p-p.I measured the amplitude at the base of the driver (TR43):- in AM Tx: 9V p-p- in SSB Tx:&nbsp; 1.8V p-pSo the signal at the base of the driver is a lot smaller in SSB. I guess this must be the reason, even if in SSB the finals work in class AB, with the full 13.8V DC applied at the collectors.I should say that I tweaked very carefully the coils upstream of the RF amplifier (L45, L46, L48 and L49) in SSB for max output, so it must be something else...Any suggestion is welcome!</blockquote>

[QUOTE="Summertown, post: 816290, member: 65077"] The HG-2SC2312 have arrived. [ATTACH type="full" alt="Finals.jpg"]63756[/ATTACH] [ATTACH type="full" alt="both.jpg"]63757[/ATTACH] hFE of 47 and 51, quite well matched. @ [USER=10801]DoctorAudio[/USER]: it was a good tip to get these(y). I replaced both finals and set the bias to 40mA for each (50mA for the driver TR43 according to the manual). I re-did the Tx alignment and now the amplitudes of the RF signals are ok :cool:. For the AM carrier unmodulated, I have limited the RF output voltage (measured with the oscilloscope on the dummy load) to 65V p-p, corresonding to 10W, right on spec. In AM with 100% modulation the excursion is nearly 120V p-p, corresonding to 35W PEP - wow! [ATTACH type="full" alt="AM max modulation.jpg"]63758[/ATTACH] In SSB, with the 2-tone signal on the mic, I get 86V p-p max excursion, corresponding to 18W PEP, slightly short of the 21W in the specs for this kit. [ATTACH type="full" alt="ssb.jpg"]63759[/ATTACH] I guess this is good enough, but there is still one thing that puzzles me. Why do I get a much higher voltage excursion in RF output for AM than for SSB? In AM I can go even higher than 120V p-p (with 100% modulation) if I turn up the AM carrier power (VR-13). But in SSB I cannot go higher than 86V p-p. I measured the amplitude at the base of the driver (TR43): - in AM Tx: 9V p-p - in SSB Tx: 1.8V p-p So the signal at the base of the driver is a lot smaller in SSB. I guess this must be the reason, even if in SSB the finals work in class AB, with the full 13.8V DC applied at the collectors. I should say that I tweaked very carefully the coils upstream of the RF amplifier (L45, L46, L48 and L49) in SSB for max output, so it must be something else... Any suggestion is welcome! [/QUOTE]

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