[Elecraft] PR-6 issue when QRO

[Gregg Marco W6IZT]

Joe:

It is a 6m only amp. Yes, the K3 is set to bypass the PR6 when on HF. The TR
relay has been replaced by a TR switch that Dick, K5AND designed that uses
Schrack relays that are spec'd to switch in 8 msec.

73
Gregg

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Joe Subich, W4TV
Sent: Sunday, April 29, 2012 11:34 AM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] PR-6 issue when QRO


Greg,

Is that SB-200 a "modified for 6 meters only" amplifier, one that has six
meters added to the HF bands or is the problem happening when operating on
HF bands?

Is the K3/PR6 configured to bypass and turn the PR6 off when operating on
HF?

73,

    ... Joe, W4TV


On 4/29/2012 11:10 AM, Gregg Marco W6IZT wrote:
> Don:
>
> I have replaced the open frame relay with Schrack relays
>
> 73
> Gregg
>
> -----Original Message-----
> From: Don Wilhelm [mailto:w3fpr at embarqmail.com]
> Sent: Sunday, April 29, 2012 10:12 AM
> To: Gregg Marco W6IZT
> Cc: 'elecraft'
> Subject: Re: [Elecraft] PR-6 issue when QRO
>
> Gregg,
>
> Unless you have changed the open frame relay in the SB-220, it will 
> take at least 15 ms to switch and be clear of the contact bounce.  I 
> would suggest you change the stock relay for something faster.
>
> 73,
> Don W3FPR
>
> On 4/29/2012 8:55 AM, Gregg Marco W6IZT wrote:
>> I use my K3 on 6 meters with a concerted SB-220. When using the PR6 
>> connected to the KXV3 as intended and using the amp, the GaAs FET is 
>> destroyed immediately. My work around was to employ an external TR 
>> relay on the K3 to switch TX RX, connecting the PR6 to the RX side of 
>> the relay and to the RX input of the KXV3.Using this arrangement has 
>> worked fine for the past few years.
>>
>> With E skip season approaching I thought that I would try to resolve 
>> this problem and get rid of the extra RF plumbing.
>>
>> My initial thought was the TR relay in the amp might be too slow and 
>> RF was being reflected back into the K3 during the transition from TX 
>> to RX. After looking at the K3 block diagram I doubt that this is the 
>> case as the PR-6 should be switched out of the circuit well before 
>> any RF is present at the output.
>>
>> For reference the TR relays in the amp are spec'ed at 8 msec to 
>> switch and the K3 is set at 8 msec TX delay, which I believe is the
default.
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net Please help support this email 
> list: http://www.qsl.net/donate.html
>
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html