James C. Owen, III wrote:
> Because--they didn't want to ban amplifiers wholesale. They just wanted to
> make it impractical to build/sell one that would amplify or could be
> modified to amplify a 5W CB rig. To do this the regulations state
> That when operated at it's full output power it must be driven with at
> least 40W. AND it must not be capable of amplifying the input RF driving
> signal by more than 15db, unless the amplifier has a designed transmitter
> power of less than 1.5KW (in such a case, gain must be reduced by the same
> number of dB as the transmitter power relationship to 1.5KW).
> SO that would mean it we wanted an amplifier with 100 W power output it
> could not have a gain of more than 3.24db. 100W is 11.76Db less than 1500W
> leaving 3.24db of the 15db allowed. To drive a 100W amplifier with the
> maximum allowed gain of 3.24db requires 47.42 watts. So we're back to the
> requirement that the amplifier not be able to be driven to full output with
> less than 40 watts and therefore it can't be driven with a qrp rig (ARGO).
> Now as you surmised you can buy a large power amplifier and since it's
> linear, drive it with a 5 watt rig legally. Let's say you bought the legal
> limit amplifier, 1500W. It has a gain of 15db, if you put 5 watts into it
> you would get 158W output. Even with a 500W amp with a legal gain of 10.25db
> if you drive it with 5 watts you will get slightly over 50W output. No, it's
> not practical (economically) to purchase a legal linear to amplify a 5 watt
> rig. BUT once again it's legal and the only way to do it.
Nicely explained, Jim.
To get back to the original question from the fellow with the Argo:
The above is probably the reason that Ten-Tec offered the Argo (5 watts
out)
for QRP, and the Scout 555 (50 watts out). The Scout is essentially the
Argo
with a 50-watt RF deck added. Not sure if Argo owners could add the RF
deck
after the fact, but it seems that for about $50-60 more, it was a
possibility.
For the ham who wasn't sure if he wanted to be exclusive on QRP, the
Scout,
which could be rolled back to 5 watts or less, would have been the
ticket at
a cost of about $60 more than the Argo.
73 de Jim - KF6CR
--
FAQ on WWW: http://www.contesting.com/tentecfaq.htm
Submissions: tentec@contesting.com
Administrative requests: tentec-REQUEST@contesting.com
Problems: owner-tentec@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|