Recent content by Alan Anderson

If we only had 50 ohm devices :), 2SC2879 is far from 50 ohms, more like 2 ohms.

The output impedance is (in general) V^2/(2*Po). The factor of 2 is based on the class of the amplifier. The lower the conduction angle the lower the factor 2 will be approaching one lower conduction angles. If you are running SSB, your output impedance is continuously changing (all over the...

They replaced C163 2pf with the mod. I removed it, had to re-tune, but it seems to work fine now. I found last night late where they changed a cap further on, going to look at that tonight. The 2000 was/is a great radio, don't know why people hack on it so much for basically insignificant...

It seems to be in the transmit signal path at C163, it is a 2SC710 running from the 8V transmit rail voltage. I measured the output at the base of TR39 and it was about the normal 86mv. Maybe they were trying to increase the bandwidth. I think I'll just put a 2pf cap back in. I don't want crazy...

I purchased a Cobra 2000 GTL and am trying to remove the mods from the radio - I removed the rotary switch style PLL mod, channels back to normal. Does anyone know what modification this is? Also an idea of what was changed to install this? If I remove it, appears to have no DC to the finals...

I have a 3300HP that when you first powered up, frequency was fine, change channels (some channels not all) and the frequency would be completely bogus - and actually drift. I ordered a PLL chip just in case, turns out changed IC6 & 7, problem solved. Don't know which one was causing the problem...