[TenTec] AM, was "Just noticed ..."

[Ken Brown]

Most SSB capable transceivers, that can also transmit in AM mode, do so 
using the same balanced modulator that they use to produce DSB. When in 
SSB mode the DSB output of the balanced modulator is run to a filter to 
reject the unwanted sideband. When transmitting in AM mode the filter is 
usually bypassed to allow both sidebands to be transmitted, and the 
modulator is either unbalanced to let carrier through, or the carrier is 
reinserted in a later stage.

Some transceivers ( such as the Kenwood TS-440 ) have independent 
control of TX audio level and carrier level, so that when AM mode is 
selected you can be transmitting anything from DSB with virtually no 
carrier (requiring the receiving station to have his BFO on, and zero 
beat to your suppressed carrier) to full carrier level AM, or even just 
a carrier with no sidebands at all, depending on how you adjust the 
controls.

Some transceivers ( such as the Kenwood TS-50 ) have preset carrier 
level when selecting AM transmit mode, so that DSB with no carrier is 
not an option.

A very few transceivers ( such as the Ten-Tec 586 Paragon II, and I 
don't know of another ) when transmitting in AM mode generate a DSB 
signal with their balanced modulator, filter it to remove one sideband, 
and reinsert the carrier, producing "SSB AM" rather than "real DSB AM". 
With the Paragon II you can select which sideband you want to transmit, 
and both sidebands (DSB) is not an option. When receiving AM with the 
585 Paragon or 586 Paragon II, you can listen to either sideband or both 
sidebands, depending on the IF filter you select and the setting of the 
VFO and Passband Tuning controls.

The 585 Paragon  cannot transmit AM in any form (other than SSB with no 
carrier), only the 586 Paragon has AM TX capability.

DE N6KB