I am going to betray my entry-level lack of understanding about the
inner workings of radio electronics here, but my question (out of
curiosity, more than anything else) is this: Ramsey Electronics offers
kits for QRP transmitters for the 20, 30 and 40-meter bands
(http://www.ramseyelectronics.com/cgi...key=QRP-SERIES)...
they are dual crystal control (they provide one, and leave space for
one more)-- is it the frequency of the crystal *only* determining the
operating band in *these particular radios* (and they are being
marketed as being for the different bands based on the frequency of the
one crystal provided), or is it something relating to the other
circuitry itself that (again, with these particular transmitters) that
is determining the operating band? I read the .pdf manual on the Ramsey
site, but I am still not certain.

Thanks for any insight-
Scott Anderson

Hi Scott,

I don't blame you for being confused--the manuals have no schematic!
But the inductors and capacitors in several places (such as the
oscillator and the low pass filter on the ouput) are different for each
band model, so you would not be able to switch a unit to a different
band just by changing the crystal.

Hope this helps (probably not what you wanted to hear),

Glenn Dixon, AC7ZN

Scott Anderson wrote:
I am going to betray my entry-level lack of understanding about the
inner workings of radio electronics here, but my question (out of
curiosity, more than anything else) is this: Ramsey Electronics offers
kits for QRP transmitters for the 20, 30 and 40-meter bands
(http://www.ramseyelectronics.com/cgi...key=QRP-SERIES)...
they are dual crystal control (they provide one, and leave space for
one more)-- is it the frequency of the crystal *only* determining the
operating band in *these particular radios* (and they are being
marketed as being for the different bands based on the frequency of the
one crystal provided), or is it something relating to the other
circuitry itself that (again, with these particular transmitters) that
is determining the operating band? I read the .pdf manual on the Ramsey
site, but I am still not certain.

Thanks for any insight-
Scott Anderson

In general when you build a transmitter you need filters designed for
the frequency band -- if no where else, then there should be a final
filter that prevents harmonics getting out.

--
-------------------------------------------
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

If you read the manual, I believe they have one manual for all models, you
insert different components based on which band you are building. The
various bands require different components in the amplifier matching, output
filter, etc circuits.

Tom - AC9TS


"Scott Anderson" wrote in message
oups.com...
I am going to betray my entry-level lack of understanding about the
inner workings of radio electronics here, but my question (out of
curiosity, more than anything else) is this: Ramsey Electronics offers
kits for QRP transmitters for the 20, 30 and 40-meter bands

(http://www.ramseyelectronics.com/cgi...action&key=QRP
-SERIES)...
they are dual crystal control (they provide one, and leave space for
one more)-- is it the frequency of the crystal *only* determining the
operating band in *these particular radios* (and they are being
marketed as being for the different bands based on the frequency of the
one crystal provided), or is it something relating to the other
circuitry itself that (again, with these particular transmitters) that
is determining the operating band? I read the .pdf manual on the Ramsey
site, but I am still not certain.

Thanks for any insight-
Scott Anderson