** especially considering that the ferrite VHF-attn beads are there to protect the hv-rf choke's self resonances from getting burned by the VHF energy that sometimes pops up in the SB-230's anode re
** Good engineering. ** with the screen circuitry you described, damaging the screens should be virtually impossible. ** it seems unlikely that ALC could safely hold the 100W output of the TS-850 do
** the 8122s' 2w control grids should be able to do without an interlock. How are the 8w screen grids protected from excessive current caused by too-light loading, from reverse screen current, and f
** In grid driven, Class AB1, there is zero grid current and zero grid-dissipation whether anode V is applied or not. The critical thing is that screen V not be applied unless anode V is present. **
** For tetrode linear amplifiers, grid bias is usually obtained from a low-current adjustable power supply. Example on Figure 4 on my Web site. - R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
The load/termination does not protect the tubes. It provides a match for the exciter. The ESR of the grid bias supply serves to limit grid current - which protects the tubes. Typically, the recommen
** In Class A, there is no grid-current, so all of the exciter power flows into the grid terminating resistor. If there is no 50-ohm grid termination, your radio will likely be in a state of vexatio
According to the characteristic-curves, at the negative peak of the driving sinewave, about 9-ohms of R (- the XC-in), At the positive peak, well over 1M-ohms of R. - R. L. Measures, a.k.a. Rich...,
** This simplified method of determining Q is the one used in Eimac's 'Care and Feeding', however, the actual Q is seemingly a bit higher. Theory and analysis have their place but the goal is that t
** True for very good, however, good enough for typical transceivers/exciters is an input capacitive reactance roughly equal to the cathode's minimum instantaneous ohms during the negative peak in t
** I found it. Thanks. ** 50-ohms is the approximate average input R. This means that the input R varies from c. 18-ohms to well over 100k-ohms during the driving cycle. Thus, a tuned input with a Q
** True, but it is still do-able. ** I think I saw some antennas, some radios and an operator. The word 'homebuilt' was not found. ... .... .... - R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
Input SWR not good enough to prevent throttle-back.. These are usually band-pass filters. If there is no tuner in the radio, yes. cheers, Mike - R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K, w
** The typical duty-cycle for SSB 2-way is c. 15%. I stock some low-L,3W-CCS @70?C Matsushita MOF resistors that will easily do 15w each in SSB service. With the ultra-fast diode shipment, I will in
** Maybe just fine with a radio with a built-in tuner. ** ... makes sense since there is nothing to balance out the asymmetrical cathode input-Z - R. L. Measures, a.k.a. Rich..., 805.386.3734, AG6K,
** If you don't find Cetron 572Bs, Osten, the Chinese ones (Taylor, Penta et cetera) reportedly work ok. However, Chinese 572Bs apparently have a bit more vhf amplification, so better vhf suppressors
** I purchased ten of 'em to distribute free for R and D. Are you still at 7509 Wakulla Dr. ? -- My guess is that the input terminator R that the diode goes in series with should be 50 - 75 ohms. If