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Unable to transmit on 147.87 FM with K3+xvtr

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Unable to transmit on 147.87 FM with K3+xvtr

Edward R Cole
Having sold all my other radios in my KX3 "garage sale", I now have
to rely on using the K3 with my DEMI 144-28 transverter for operating
on local 2m repeaters.  I thought the K3 was capable of providing
drive on 28-32 MHz when in transverter mode so the whole 2m band
would be covered.

I get 0.73mw (-1.5 dBm) max drive at 146.52 MHz (K3=30.52-MHz) but
only -15 dBm indicated at 147.87 (K3=31.87 MHz).
ergo no output on 2m much above 30.5 MHz due low drive from the
K3.  The K3 does receive the entire 2m band (covers 28-32 MHz).  BTW
the max drive is 1.8mw from 28-30 MHz.

I guess this will mean I am unable to use many of the 2m repeater
frequencies (146-147.99) until I receive my new KX3.  Hopefully it
can generate 1-2w min. up to 32 MHz.  If not then I will have to
modify my transverters to have two LO frequencies to cover that range
(116 and 118 MHz).


73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
DUBUS Magazine USA Rep [hidden email]
======================================

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Re: Unable to transmit on 147.87 FM with K3+xvtr

Edward R Cole
Ron,

One of the specs that I noted when buying the K3 was that the 30-MHz
limit was "relaxed" for allowing operation above 30-MHz (this is
printed on page 39 of the manual).  But then it mentions Rx and Tx
signals will fall off.  Well, I expected there to be something there.

 From my testing the receiver will work 28-32 MHz OK but the
transmitter is effectively limited to under 30.7 MHz.  This does
permit using the simplex FM channels near 146.52 and the repeaters up
to 147 MHz since they transmit on a 0.6 MHz low-split.  But none of
the repeater channels about 147 can be used.

My DEMI L144-28HP-DRX transverter is optimized for 144-146 and way to
difficult to add a second xtal.  Even if I could drive it the output
falloff may be excessive (I have not way of knowing that at
present).  This transverter was not bought for FM operations and was
never intended for that use by me.  This is temporary till the KX3 arrives.

I have an older DEMI 144-28LP transverter (circa 2007 and out of
production) that apparently had the option for a second LO freq.  I
never completed the Tx side since it was used as a Rx converter for
the SDR-IQ.  But now I am working on getting the Tx side completed
and bought a 14w RF module to increase the output to ~10w from the
roughly 20mw drive level available.  The transverter was originally
available for either low-power (mw) or 25w out.  I bought the LP
version since my main use was for receive.

I'm setting this up to drive with the KX3 (once I get it).  My other
use was driving mw transverters where 20mw is adequate.  I will
explore getting a second xtal to be able to operate 144-148.  Once
the internal Elecraft 2m Transverter comes out I will install it.

Ed


At 01:00 PM 11/25/2011, Ron D'Eau Claire wrote:

>I believe that's the case, Ed. The K3's band pass filters roll off at 30
>MHz. The K144XV option does cover the whole 8 MHz of the 2-meter band but
>does it in two bands that switch automatically and seamlessly as the K3 is
>tuned from 144 to 148 MHz. The main K3 never tunes beyond 28 to 30 MHz. The
>K144XV switches the local oscillator frequency as needed to do this.
>
>If practical, you might consider changing the L.O. frequency in your
>transverter to shift the tuning range to reach the repeater frequencies.
>
>Ron AC7AC
>
>
>-----Original Message-----
>
>Having sold all my other radios in my KX3 "garage sale", I now have
>to rely on using the K3 with my DEMI 144-28 transverter for operating
>on local 2m repeaters.  I thought the K3 was capable of providing
>drive on 28-32 MHz when in transverter mode so the whole 2m band
>would be covered.
>
>I get 0.73mw (-1.5 dBm) max drive at 146.52 MHz (K3=30.52-MHz) but
>only -15 dBm indicated at 147.87 (K3=31.87 MHz).
>ergo no output on 2m much above 30.5 MHz due low drive from the
>K3.  The K3 does receive the entire 2m band (covers 28-32 MHz).  BTW
>the max drive is 1.8mw from 28-30 MHz.
>
>I guess this will mean I am unable to use many of the 2m repeater
>frequencies (146-147.99) until I receive my new KX3.  Hopefully it
>can generate 1-2w min. up to 32 MHz.  If not then I will have to
>modify my transverters to have two LO frequencies to cover that range
>(116 and 118 MHz).
>
>
>73, Ed - KL7UW, WD2XSH/45
>======================================
>BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
>EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
>DUBUS Magazine USA Rep [hidden email]
>======================================
>
>______________________________________________________________
>Elecraft mailing list
>Home: http://mailman.qth.net/mailman/listinfo/elecraft
>Help: http://mailman.qth.net/mmfaq.htm
>Post: mailto:[hidden email]
>
>This list hosted by: http://www.qsl.net
>Please help support this email list: http://www.qsl.net/donate.html


73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 50-1.1kw?, 144-1.4kw, 432-QRT, 1296-?, 3400-?
DUBUS Magazine USA Rep [hidden email]
======================================

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

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