[Lowfer] WD2XSH/10 WD2XSH/7 and WG2XIQ around 476 kHz & HD-1420 re-capped

[Michael Sapp]

Hi Dex:  I heard you about the same the evening before as well.  I re-capped 
an HD-1420 VLF converter and have been comparing it's performance above 450 
kHz to the FT-847, so it was helpful to have some active stations for on-air 
comparisons the last few evenings.

BTW, taking a hint from W1VD's pre-amp designs, I changed the input coupling 
and emitter bypass caps to 10uf non-polarized in the 2N3904 preamp of the 
HD-1420 at it made a large improvement.  NAU on 40.75 kHz came up 20dB (as 
measured with step attenuators), "MP" in daylight on 137 kHz came up 9 dB, 
and EAR in daylight on 188 kHz came up 6dB.

 The original .1uf emitter bypass disc ceramic cap on the 2n3904 preamp 
barely made 1-M-ohm in a DC test, so I replaced all the other .1 bypass caps 
with newer .1uf metal film caps (which all passed a 2000 M-ohm check). There 
is a chance the mediorce .1uf cap on the 2n3904 was part of the preamp 
performance issue in the HD-1420.

Encourged by those results, I changed the .01 coupling and bypass caps to 
the input of the MC1496 active mixer to 10 uf non-polarized, but that did 
not seem to make much difference.  I may try .1uf caps to the MC1456 input 
after some additional on-air receiving tests, it's data sheet shows the use 
of .1uf caps on the input in an example circuit.

Right now I would havc to say I have the HD-1420 working as well or better 
than a re-capped BC-453 here for the same receiver bandwidth in the NDB 
band.  I feed both of them with a BN-73-03 transformer like the W8JI 
design--but three ferrites end to end instead of one of them to lower the 
insertion loss at LF.  The HD-1420 needs a front end BCB filter to hear well 
at LF and (obviously from a 3IOP standpoint) the BC-453 does not.

Thanks for listening/reader the above rant. I just wanted to let you know 
your 137 and 500 kHz activity is appreciated up this way.

73  Mike wa3tts


----- Original Message ----- 
From: "Dexter McIntyre W4DEX" <dexter.mc at gmail.com>
To: "Michael Sapp" <wa3tts at verizon.net>
Sent: Thursday, October 25, 2012 8:13 AM
Subject: Re: [Lowfer] WD2XSH/10 WD2XSH/7 and WG2XIQ around 476 kHz


> Very nice copy Mike.  Thanks for posting the video.
>
> Dex
>
> Michael Sapp wrote:
>> Hi All: Three stations at once in my receiver bandpas this evening....
>>
>> http://www.youtube.com/watch?v=_7FeONvCKho&feature=channel&list=UL
>>
>> 73  Mike wa3tts
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