Fwd: FT5000 PIN Diodes

[KARL MARDERIAN]

Sent from my iPhone

Begin forwarded message:

> From: Karl Marderian <[hidden email]>
> Date: November 15, 2010 3:23:33 PM PST
> To: "[hidden email]" <[hidden email]>
> Subject: FT5000 PIN Diodes
>

> As I remember, when I bought my K3. I want to receive AM, even down to the low broadcast band. I was told that I needed the optional receive plug. This was to bypass the PIN Diodes.
> Maybe this is why Yeasu did not use them.
> N6XVT. Karl
>
>
> Sent from my iPhone
______________________________________________________________
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

[wayne burdick]

Hi Karl,

I think there are a few issues to clear up here.

The K3 uses PIN diodes that are rated down to around 500 kHz, so they  
won't cause any IMD due to broadcast band signals. Such PIN diodes are  
readily available, but more expensive, so I can see why a manufacturer  
might want to use relay switching instead. That wasn't an option in  
the K3 -- it had to have solid-state T/R switching.

In addition to using the right PIN diodes, we took two extra  
precautions.

First, we incorporated a high-pass filter into the T/R switch. It  
rolls off signals below 1 MHz to ensure that extremely strong signals  
in the 500 kHz range or below are attenuated. The attenuation at 500  
kHz is about 20-25 dB. This is not a problem for casual broadcast band  
DXing.

However, we also provide a way around the T/R switch: the RX ANT IN  
jack on the KXV3 or KXV3A module. Most broadcast-band enthusiasts  
connect their low-band receiving antenna directly to RX ANT IN,  
bypassing the high-pass filter. If you still have a particular station  
that's a problem, you could use an external notch filter in line with  
RX ANT IN.

73,
Wayne
N6KR


On Nov 15, 2010, at 3:33 PM, Karl Marderian wrote:

>
>
> Sent from my iPhone
>
> Begin forwarded message:
>
>> From: Karl Marderian <[hidden email]>
>> Date: November 15, 2010 3:23:33 PM PST
>> To: "[hidden email]" <[hidden email]>
>> Subject: FT5000 PIN Diodes
>>
>
>> As I remember, when I bought my K3. I want to receive AM, even down  
>> to the low broadcast band. I was told that I needed the optional  
>> receive plug. This was to bypass the PIN Diodes.
>> Maybe this is why Yeasu did not use them.
>> N6XVT. Karl

______________________________________________________________
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

[Edward R Cole]

For operating as WD2XSH/45 on 495.6 KHz,  I connect thru the KVX3A Tx
and Rx terminals, and run in "TEST" mode so I bypass the HP filter to
get good sensitivity below 600-KHz.  I added a Clifton-Labs BC Band
filter to suppress BC stations on the lower end from spattering down
into 500-KHz (essentially raising the noise floor).

73, Ed - KL7UW & WD2XSH/45 (FCC experimental license)

------------------------------

Message: 40
Date: Mon, 15 Nov 2010 15:55:48 -0800
From: Wayne Burdick <[hidden email]>
Subject: Re: [Elecraft] Fwd: FT5000 PIN Diodes
To: Karl Marderian <[hidden email]>
Cc: "[hidden email]" <[hidden email]>
Message-ID: <[hidden email]>
Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes

Hi Karl,

I think there are a few issues to clear up here.
----snip---

First, we incorporated a high-pass filter into the T/R switch. It
rolls off signals below 1 MHz to ensure that extremely strong signals
in the 500 kHz range or below are attenuated. The attenuation at 500
kHz is about 20-25 dB. This is not a problem for casual broadcast band
DXing.

However, we also provide a way around the T/R switch: the RX ANT IN
jack on the KXV3 or KXV3A module. Most broadcast-band enthusiasts
connect their low-band receiving antenna directly to RX ANT IN,
bypassing the high-pass filter. If you still have a particular station
that's a problem, you could use an external notch filter in line with
RX ANT IN.

73,
Wayne
N6KR





73, Ed - KL7UW, WD2XSH/45
======================================
BP40IQ   500 KHz - 10-GHz   www.kl7uw.com
EME: 144-800*w, 432-100w, 1296-testing*, 3400-winter?
DUBUS Magazine USA Rep [hidden email]
======================================
*temp not in service
______________________________________________________________
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