K3: VHF/UHF transverters

[Sverre Holm (LA3ZA)]

We are considering a K3 for our clubstation where 2m and 70 cm is important. Therefore I have some questions which I haven't been able to find answers to by searching the lists.

1. Are the external (K144XV, 25 W) and internal (XV144, 10 W) 2m transverters identical with respect to receiver specs?

2. Is there a schematic on the web for the internal 2m transceiver, XV144?

3. If we want also to run an K432XV do we still have a choice between running an internal or an external 2m transverters?

4. IF the K3 has two receivers, can one listen on 2 m and the other on 70 cm?


Thanks,

[KK7P]

Comments below
> 1. Are the external (K144XV, 25 W) and internal (XV144, 10 W) 2m
> transverters identical with respect to receiver specs?
>  
The noise figure at the antenna jack on the internal transverter may be
slightly higher due to the PIN diode T/R switch.  The external
transverter has relay-based T/R switching.
> 2. Is there a schematic on the web for the internal 2m transceiver, XV144?
>  
The schematic has not been posted yet.  However, I just compared the
receiver section of the K144XV the XV144 and, apart from the relay
versus PIN diode switch, they are essentially identical. I say
essentially because a component value may be slightly different due to
stray or parasitic PCB layout differences, but the circuit topology and
active devices are identical.
> 3. If we want also to run an K432XV do we still have a choice between
> running an internal or an external 2m transverters?
>  
Yes.  The internal 2m module has its own set of switched IF connectors
on the KXV3A (not KXV3) interface.  External Elecraft transverters hook
up to the external jacks.  If you use external 2m and 70cm Elecraft
transverters, they will both conenct tot he K3.
> 4. IF the K3 has two receivers, can one listen on 2 m and the other on 70
> cm?
>  

I believe the answer is yes, *but* one will have to be interfaced using
the regular antenna connections.  The KXV3(A) only provides connection
to one receiver.  This is not compatible with the usual "daisy chain"
configuration of XV-series transverters.

73,

Lyle KK7P
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[KK7P]

>> 4. IF the K3 has two receivers, can one listen on 2 m and the other on 70
>> cm?
>>  
>>    
>
> I believe the answer is yes, *but* one will have to be interfaced using
> the regular antenna connections.  The KXV3(A) only provides connection
> to one receiver.  This is not compatible with the usual "daisy chain"
> configuration of XV-series transverters.


I meant, using both receivers simultaneously is not compatible with the
usual "daisy chain" configuration of XV-series transverters.  The
KXV3(A) *is* compatible with such daisy chaining, of course.

73,

Lyle KK7P
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[AD6XY]

Hi Lyle,

A question set on the new transverter interface KXV3A and the K144.

How many internal ports does the KXV3 have? If it is only one is the KV144 daisy chainable like the XV144. If yes when is the KV70/220/432/1296 coming out!

There was discussion on low level outputs for driving gear for higher bands. I see these are not currently connected. Has that plan now been dropped/put on hold or is it being done by bypassing the PA and using the antenna socket?

Finally..... is it possible to get 8-12V on the 144MHz antenna port on TX like on the FT290? This is how many of us drive microwave transverter PTTs. It would allow me to use my K3 on 24GHz.

Mike

[M0XDF]

Hmmmm - I have an unbuilt XV144 and was not going to buy the K144XV because I thought I had read somewhere that the XV144 would be sufficiently better to warrant using the XV144 - but that would generally be portable or at an alternative address and via a 100W PA. Now wondering if the additional kit to carry (the XV144) makes it worth it.

The K144XV will give 8-10 Watts, the XV144 20-25 Watts - strikes me as I'd have to drive a PA with at least 10 and that would be pushing the K144XV, whereas I could reasonably get 15 - 20 from the XV144 and not get it too hot (a known problem?) and not over-drive them either.
73 de M0XDF
--
Mathematics is the language with which God has written the universe.
-Galileo Galilei, physicist and astronomer (1564-1642)

On 12 Feb 2010, at 23:29, Lyle Johnson wrote:

> Comments below
>> 1. Are the external (K144XV, 25 W) and internal (XV144, 10 W) 2m
>> transverters identical with respect to receiver specs?
>>
> The noise figure at the antenna jack on the internal transverter may be
> slightly higher due to the PIN diode T/R switch.  The external
> transverter has relay-based T/R switching.
>> 2. Is there a schematic on the web for the internal 2m transceiver, XV144?
>>
> The schematic has not been posted yet.  However, I just compared the
> receiver section of the K144XV the XV144 and, apart from the relay
> versus PIN diode switch, they are essentially identical. I say
> essentially because a component value may be slightly different due to
> stray or parasitic PCB layout differences, but the circuit topology and
> active devices are identical.
>> 3. If we want also to run an K432XV do we still have a choice between
>> running an internal or an external 2m transverters?
>>
> Yes.  The internal 2m module has its own set of switched IF connectors
> on the KXV3A (not KXV3) interface.  External Elecraft transverters hook
> up to the external jacks.  If you use external 2m and 70cm Elecraft
> transverters, they will both conenct tot he K3.
>> 4. IF the K3 has two receivers, can one listen on 2 m and the other on 70
>> cm?
>>
>
> I believe the answer is yes, *but* one will have to be interfaced using
> the regular antenna connections.  The KXV3(A) only provides connection
> to one receiver.  This is not compatible with the usual "daisy chain"
> configuration of XV-series transverters.
>

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[David Pratt]

In a recent message, "David Ferrington, M0XDF" <[hidden email]>
writes
>
>The K144XV will give 8-10 Watts, the XV144 20-25 Watts - strikes me as
>I'd have to drive a PA with at least 10 and that would be pushing the
>K144XV, whereas I could reasonably get 15 - 20 from the XV144 and not
>get it too hot (a known problem?) and not over-drive them either.

Your XV144 should not get too hot, David.  I presume that yours will
have vent holes in the top and bottom covers whereas the early ones
(like mine) did not.  Now that I have provided ventilation I do not have
a heat problem and can merrily run mine up to 25W. The Mitsubishi
RA30H1317M PA module is in fact rated to have a Pout >30W at up to
175MHz.
--
David G4DMP
Leeds, England, UK



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[M0XDF]

Thanks, I don't actually know about the vent holes - I haven't done an inventory of it yet and I've had it since I got the K3 - talk about not having time!

Don't suppose you have an K144XV to compare against?
--
Don't say you don't have enough time. You have exactly the same number of
hours per day that were given to Helen Keller, Pasteur, Michaelangelo,
Mother Teresa, Leonardo da Vinci, Thomas Jefferson, and Albert Einstein.
-H. Jackson Brown, Jr., writer

On 13 Feb 2010, at 11:15, David Pratt wrote:

> In a recent message, "David Ferrington, M0XDF" <[hidden email]>
> writes
>>
>> The K144XV will give 8-10 Watts, the XV144 20-25 Watts - strikes me as
>> I'd have to drive a PA with at least 10 and that would be pushing the
>> K144XV, whereas I could reasonably get 15 - 20 from the XV144 and not
>> get it too hot (a known problem?) and not over-drive them either.
>
> Your XV144 should not get too hot, David.  I presume that yours will
> have vent holes in the top and bottom covers whereas the early ones
> (like mine) did not.  Now that I have provided ventilation I do not have
> a heat problem and can merrily run mine up to 25W. The Mitsubishi
> RA30H1317M PA module is in fact rated to have a Pout >30W at up to
> 175MHz.
> --
> David G4DMP
> Leeds, England, UK
>
>
>
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> Elecraft mailing list
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>
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[Sverre Holm (LA3ZA)]

Hi Lyle,

Thanks for your response. I take this to mean that with an internal 2 m transverter it can listen to 2 m on rx A, while rx B listens simultaneously through an external XV432 on 70 cm.

KK7P wrote

>> 4. IF the K3 has two receivers, can one listen on 2 m and the other on 70
>> cm?
I meant, using both receivers simultaneously is not compatible with the
usual "daisy chain" configuration of XV-series transverters.  The
KXV3(A) *is* compatible with such daisy chaining, of course.

[KK7P]

> A question set on the new transverter interface KXV3A and the K144.
>
> How many internal ports does the KXV3 have?
One - see the schematics on the website.

> Finally..... is it possible to get 8-12V on the 144MHz antenna port on TX
Looks like +5V with a nominal 4.7K source impedance during Tx.

73,

Lyle KK7P
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[KK7P]

Hello Sverre!
> Thanks for your response. I take this to mean that with an internal 2 m
> transverter it can listen to 2 m on rx A, while rx B listens simultaneously
> through an external XV432 on 70 cm.
>  

It should be possible to do exactly as you suggest, but I cannot say if
the UI currently supports this or not. I simply do not know.

73,

Lyle KK7P
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