The Larkspur C11 transmitter
I bought one 30 years ago intending it to give me incentive to learn
Morse. I still havent learned morse, but I still have the C11 and
now I dont have to learn morse ! Cool! It is primarily a CW unit
but will do AM (phone) MCW and FSK. Covers 2Mhz to 16Mhz (
completely misses 160M )
Uses hi stability master oscillator which is multiplied for the higher
bands. The master oscillator module is a masterpiece of precision
mechnical engineering. All I have is excepts from the manual, but they
are schematics!
The
usual advice applies, the full EMER is available from
www.royalsignals.org , their manual is complete and the quality is superior.
These images are links to high resolution images
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| page 7 (?) | page 11 | page 9 (maybe) |
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| relays and filaments | mic amp, amc, CW sidetone | AM modulator and amc |
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| audio chain, amc and AM modulator | buffer amp, harmonic multipliers and RF power amp | |
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| external rotary transformer unit | more of the schematic | more of the schematic |
Copious apologies for the quality, but they have gone through many
generations of copies of copies of copies of copies and my
"originals" have been yellowing away for the last thirty years.
This was the transmitter portion of a radio transmitter combination. I
believe the compansion radio equipment was called an R210, I remember
looking at one in the disposals shop when I
was 15 and feeling sad that I would never have enough pocket money to
buy it back then. People tell me that the radio was pure gold, so
solid that it
could be pushed of the bench and fall on to concrete and the beat note
would not change. I dont doubt it. I still dont have an R210.
Old hams I meet tell me "...ahhh I used tah have one of
them...threw it away years ago...didnt have a product
detecter...useless !! ahhh... " and so on. There were for a while
C11 sets going for a song in Melbourne from army disposal
vendors. I bought mine in 1978 for ten dollars. I do not have the
rotary transformer power supply unit and I have not had time to biuld a
PSU for this transmitter yet. If you go to Seaworld in Queensland
there is the power unit on display as a prop in the Burmuda Triangle
Ride. Its meant to look like a mysterious piece of WW2 technical
paraphernalia....kind of breaks the magic if you know what the prop
actually is!
Here
is some images of the C11 interior. They dont biuld them like
this anymore! Needless to say the biuld quality is impeccable, true of
all the Larkspur radios that I have seen.
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| elaborate clockwork for tuning | green box is the VFO, turbine for cooling | |
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| vfo and AM plate modulation transformer,below 100KCS crystal harmonic generator | RF power amplifier | |
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