K3 transverter using 14 MHz I.F. - upper freq limit ?

[GM4JJJ]

I am thinking about a K3 for transverting to 144-146MHz using my existing transverter which has a 14-16MHz I.F.

It works well with the KX3,  does the K3 similarly allow transmit and receive on the transverter ports beyond the ham band frequency limits? I don't want to be limited to 144.350 MHz upper frequency.

73 from David GM4JJJ
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[Don Wilhelm-4]

David,

I don't know if the K3 transverter IF output is limited to the ham bands
or not.  However, if it is, contact Elecraft report and they may be
willing to send you a program to run which will open up the transmit limits.
Be aware that the ham band bandpass filters may limit the power output
as well as the receive passband.  You may want to install the KBPF3 if
you do not already have one in your K3

73,
Don W3FPR

On 2/22/2016 4:09 PM, David Anderson wrote:
> I am thinking about a K3 for transverting to 144-146MHz using my existing transverter which has a 14-16MHz I.F.
>
> It works well with the KX3,  does the K3 similarly allow transmit and receive on the transverter ports beyond the ham band frequency limits? I don't want to be limited to 144.350 MHz upper frequency.
>
>

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[GM4JJJ]

Thanks Don,

On further internet searching I think I have answered my own question, but am happy to be corrected.

I suspect that the K3 Transverter ports reflect the same frequency limits as programmed into the radio as the main antenna port. The K3 is apparently software transmit ham band limited as far as I have read. It can be unlocked for "MARS" use, and that apparently gives general coverage transmit except around the IF and certain restrictions on power on the 27 MHz band.  

I don't have a K3 yet, I am thinking about one, but am also considering all other options.

The KX3 with PX3 that I have performs exceptionally well on receive with my VHF transverter, but the transmit wideband noise at 50 kHz offset and beyond and some rather bad discrete spurious outputs are poor by comparison and I am not particularly happy running it into a Legal Limit amplifier if there are stations in close proximity (20km).  I realise that the KX3 is really designed as a QRP HF rig where such transmit noise and spurious outputs would be buried in the RF pollution on HF, but on VHF that isn't the case and greater care has to be taken.

So, armed with recently published figures comparing various transceivers I am looking at alternatives, the K3S is the best of the bunch, then the K3. I am excluding the top of the range Flex, as I prefer a real radio with knobs on. See RadCom Magazine March 2016 p22-27 High Performance VHF/UHF contest stations by Alwyn Seeds G8DOH.

Of course finding a used K3 with the right options that I need (and they quickly add up) may be a problem.

Prices in the UK from the dealer are £ for $, so buying direct from Elecraft in the USA is a still a better deal even with today's high shipping costs and 20% VAT.  At one time it was cheaper to take a transatlantic trip and bring a K3 back and still save money.

Slightly below the K3 but better than the KX3 in transmit purity at 50 kHz offset is the TS-590SG and it has an easy hardware mod for general coverage transmit coverage, so that is another option. However I do like Elecraft so provided it can do what I need that is what I would prefer.

I was surprised to find how out of calibration my transmit carrier null and opposite transmit sideband suppression was on my KX3 when I put it on an analyser. I was able to improve it by a great many dBs on all bands. I wonder as it was "built" by the UK dealer and I believe they align them.

73 from David GM4JJJ

> On 22 Feb 2016, at 22:36, Don Wilhelm <[hidden email]> wrote:
>
> David,
>
> I don't know if the K3 transverter IF output is limited to the ham bands or not.  However, if it is, contact Elecraft report and they may be willing to send you a program to run which will open up the transmit limits.
> Be aware that the ham band bandpass filters may limit the power output as well as the receive passband.  You may want to install the KBPF3 if you do not already have one in your K3
>
> 73,
> Don W3FPR
>
>> On 2/22/2016 4:09 PM, David Anderson wrote:
>> I am thinking about a K3 for transverting to 144-146MHz using my existing transverter which has a 14-16MHz I.F.
>>
>> It works well with the KX3,  does the K3 similarly allow transmit and receive on the transverter ports beyond the ham band frequency limits? I don't want to be limited to 144.350 MHz upper frequency.
>

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[Don Wilhelm-4]

David,

Ordering direct from Elecraft, my understanding it that if you order the
K3S-F you will endure both customs fees and VAT.
If you order the kit version, it should not be subject to customs fees,
but VAT will still have to be paid.

I believe there are benefits to ordering from Waters & Stanton, or from
QRP Project in Germany.  Extended warranty is one, and more local
warranty service without the expense of shipping back to Watsonville,
CA.  I am lead to believe (but do not quote me), that W&S as well as QRP
Project service only what they sell.  There is an Elecraft Service
Center in Italy that I believe services the full line.
David Shoaf at Elecraft acting in his role of pre-sales advisor
([hidden email]) can give you full details and correct any
misconceptions that I may have injected into this email.

73,
Don W3FPR

On 2/22/2016 6:42 PM, David Anderson wrote:

> Thanks Don,
>
> On further internet searching I think I have answered my own question, but am happy to be corrected.
>
> I suspect that the K3 Transverter ports reflect the same frequency limits as programmed into the radio as the main antenna port. The K3 is apparently software transmit ham band limited as far as I have read. It can be unlocked for "MARS" use, and that apparently gives general coverage transmit except around the IF and certain restrictions on power on the 27 MHz band.
>
> I don't have a K3 yet, I am thinking about one, but am also considering all other options.
>
> The KX3 with PX3 that I have performs exceptionally well on receive with my VHF transverter, but the transmit wideband noise at 50 kHz offset and beyond and some rather bad discrete spurious outputs are poor by comparison and I am not particularly happy running it into a Legal Limit amplifier if there are stations in close proximity (20km).  I realise that the KX3 is really designed as a QRP HF rig where such transmit noise and spurious outputs would be buried in the RF pollution on HF, but on VHF that isn't the case and greater care has to be taken.
>
> So, armed with recently published figures comparing various transceivers I am looking at alternatives, the K3S is the best of the bunch, then the K3. I am excluding the top of the range Flex, as I prefer a real radio with knobs on. See RadCom Magazine March 2016 p22-27 High Performance VHF/UHF contest stations by Alwyn Seeds G8DOH.
>
> Of course finding a used K3 with the right options that I need (and they quickly add up) may be a problem.
>
> Prices in the UK from the dealer are £ for $, so buying direct from Elecraft in the USA is a still a better deal even with today's high shipping costs and 20% VAT.  At one time it was cheaper to take a transatlantic trip and bring a K3 back and still save money.
>
>

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[Edward R Cole]

David,

I don't have an answer for your question though well aware that
bandpass filter affect on use of K3 IF for transverters.

For Rx, if you have the KBPF3 installed, it will extend beyond 14.350
but unknown if that is true for Tx.

I use 28-32 MHz as IF for my VHF/UHF transverters up thru 1296.  Many
are probably unaware that the K3 will receive up to 32-MHz in
transverter mode.  However RF output drops off severely above
30-MHz.  My 50w transverter output at 146.52 (IF=30.52) is 6w due to
low drive from the K3.  At 146.000 output is 15w.  At 145.800
35w.  And 144.000-145.500 50w.

Use of my KX3-2M is for the full 144-148 MHz band, making it way more
usable as a multi-mode 2m radio.

But my use of the K3+ 2m DEMI transverter is primarily for the bottom
end 144-144.200.  I have 2m FM radios for the rest of the band (and
the KX3-2M, of course).

73, Ed - KL7UW
http://www.kl7uw.com
     "Kits made by KL7UW"
Dubus Mag business:
     [hidden email]

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[GM4JJJ]

Thanks again Don.

Yes I would not have the brass neck to expect the UK dealer to help if I had a problem after bypassing them on the purchase.

It is unlikely I will buy anything other than a kit from the USA. So no customs duty, though sometimes the customs get that wrong and you need to appeal. There was a letter about that in Radcom this very month.

Either that or a I get a used unit from someone in the UK. That is my preferred option and I have had one lead so far from a fairly local ham.

I found some interesting info on the K3 transmit phase noise on various bands today. 14 MHz looks like one of the best bands to use as the IF provided I can transmit up to about 14.4 MHz.

http://www.ok2kkw.com/next/staronove_vyzvy.htm

and


http://www.ok2kkw.com/xyz/om3w/transvertor_om3w_en.htm

73


David Anderson GM4JJJ


> On 23 Feb 2016, at 00:16, Don Wilhelm <[hidden email]> wrote:
>
> David,
>
> Ordering direct from Elecraft, my understanding it that if you order the K3S-F you will endure both customs fees and VAT.
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