[R-390] Below 500khz?

[blw]

Robert and Roy,

Phil Atchley was on the list for a while and he did this LF connection per
HSN. I sent him copies of the plans. He didn't mention low sensitivity, but
he did mention low output on the audio. He liked the radio but he had wrist
problems with fine tuning. I tried to tell him to use the BFO more but I
don't think he did.

I've been DXing LF heavy since last September on a RBL-5 and belong to the
NDBList. The big things you absolutely have to have in order to get decent
logs are the things we tend to not want attached to boatanchors. One, you
need an amplified antenna. Period. I did a winter of DXing with a passive
loop of good design, and then bought the Quantum QX Pro loop for this past
winter. No comparison! My best log was 5400 miles from S. America. I had
some 4000 miles ones. The other thing you have to have is a good filter
unit. I used a JPS NIR-12 the first year and almost all of this past winter.
I recently bought a used Datong FL-3 that would have upped my logs by quite
a lot if I had it when the winter DX was good. This is the last of the
analog filter units and is made in England. A lot of my catches are made
with a filter setting of around 500 Hz. The audio on the RBL-5 is so good
that I can get a lot wide open at 3400 kHz width, but I would miss a lot
too. There are normally 4-5 good beacons on any one freq that is propagating
well. You can't get those unless you get very narrow with a good
loop...imho. I got a lot of catches with the RBL-5/Quantum/NIR-12 that I'm
sure were viewed skeptically. Wait until next winter with the FL-3. It is
going to be much better over the NIR-12.

The thing is, if you just hook up a passive antenna you will log a few
beacons. You will get a few more with the winter DX is good, but you won't
log 10% of what you can get with an amplified antenna and a good filter
unit. 

As to the R-390A and the Quantum loop, I logged some good beacons down to
around 510 kHz last winter, or some freq near that. They drop off below that
freq for a block, but the radio was absolutely superb on those beacons. Very
quiet and very sensitive. If only we had a boatanchor LF converter of
suitable quality we would have the best LF radio around.


Barry


> At 06:27 PM 5/16/03 -0500, Robert M. Bratcher Jr. wrote:
>> Is there a way to make an 390a receive below 500khz all by itself?
> 
> Yes. An article in Hollow State News   detailed the technique, but
> basically it is this:
> 
> Disconnect your regular antenna (or pull out the RF Amplifier tube) and
> attach it or your LF antenna to test point E208 on the RF deck.
> 
>> Is it as sensitive as above 500?
> 
> No.
> 
>> What happens when you hit 500? It sounds like the audio gets muted but I'm
>> not sure....
> 
> With the receiver in normal configuration, the front end tuned circuits do
> not respond well below 500kc.. all signals get attenuated compared to above
> that frequency.
> 
>> If it's not possible then I'll build a converter that puts 0 to 500
>> between 4 & 4.5mhz.
> 
> A number of converters are available to do the job, Heath made one.  Look
> below for reference to at least one converter article.