Hi Gary/all:

Thanks for giving us the blow-by-blow on this! This is a good guide to the procedure.

This is similar to what I did when I was out at the beach with my little active-passive loop, the tuning of which is very precise and so it's easy to miss where I am actually trying to be. Using the Sony 7600GR and its fairly useless tuning LCD indicator as a spotter, I would set it to SSB in order to get a het on a TP/TA, then tune the loop aurally to the het - this actually works pretty well since the het really jumps out, and is about as tough to miss as the Christmas tree lights on the 2010 :-). I would then do as Gary suggests - move the spotter aside and put the Ultralight in its place (or simply retune the Ultralight if coupling it to the loop with a little ferrite coupler, which is more convenient and provides better signal transfer).

Gary - with a large loop, do you notice any difference in the resultant signal strength between a stock PL-380 and an Amidon PL-380? It seems that if the loop is big enough, it would more or less completely dictate the signal level, making the stock PL-380 viable as a TA/TP receiver if one has a big loop in the mix.

Kevin S
Bainbridge Island, WA

--- In ultralightdx@yahoogroups.com, D1028Gary@... wrote:
>
> Hello All,
>
> Ralph Pollock asked a very interesting question about peaking external
> antennas for use with the Tecsun DSP models-- a subject which has also
> interested me from the beginning, due to my use of the radios with large tuned
> passive loops during DXpeditions. The correspondence below may be of interest
> to those with similar questions.
>
> 73, Gary
>
> From: d1028gary@... ..>
> To: Pollock,Raphael E
> Sent: Tue Jan 12 20:10:10 2010
> Subject: Re: LTG450GW Filter Modification to the SRF-M37V/W Models
>
> Hello Ralph,
>
> Thanks for your comments on the PL-310/380 experimentation, which are
> appreciated.
>
> Since these Tecsun DSP models have a somewhat delayed response to sudden
> boosts in RF signal power from external antennnas, they typically don't have
> the sharp audio peaks normally found on radios like the ICF-2010, E5 and G6
> when external antennas are peaked on their tuned frequency. The digital
> signal strength readings on the PL-310/380 displays are also of little help,
> since both models use an averaging system which causes a delay in changes
> to the digital display reading. For this reason, even I have found it
> counter-productive to try peaking external antennas by listening to the
> PL-310/380 audio, or watching the RSSI or S/N readings change on the digital
> display.
>
> After receiving your email, I did attempt to use a Q-stick+ for peaking a
> PL-380, and while inconvenient, it did provide a significant signal boost
> according to the S/N digital display reading (after a wait of about 5
> seconds). The problem is that the PL-380 has no immediate response (either audio
> or visual) to the peaking of the external Q-stick on its tuned frequency,
> making it tough to determine when you have hit the peak. You need to wait
> about 5 seconds to find out.
>
> After developing a series of huge loop antennas (with the related
> technical article linked at _http://www.mediafire.com/?igw1zjwfzmw_
> (http://www.mediafire.com/?igw1zjwfzmw) ) and using them exclusively during DXpeditions
> with the Tecsun models, I have found that the best way to adjust these
> monster loops to the PL-310/380's tuned frequency is to first use the ICF-2010's
> red LED display to peak the loops, then simply bring the PL-310/380's into
> the inductive coupling field of the loops. The ICF-2010 is ideal for this
> purpose, especially on dark ocean beaches where the LED signal strength
> display will light up like a Christmas tree when the loops are matched in
> frequency.
>
> For the external antenna systems you have described, Ralph, they actually
> will give a fairly decent boost to the Tecsun models' AM reception once the
> frequencies are peaked, as described above. I wish I could build you a
> booster bar that would give you an immediate peaking response from the Tecsun
> models, but this is probably one congenital quirk that we will need to live
> with.
>
> 73 and Good DX, Gary
>
>
>
>
>
> In a message dated 1/12/2010 8:55:23 A.M. Pacific Standard Time,
> rpollock@... writes:
>
> Dear Gary: I have been following your experiemnts with the 310/380 radios
> with keen interest. I am wondering if the 81 turn Amidon 7.5" ferrite
> could be adapted as an inductively connected booster for these radios. If that
> design would not work i am wondering if you would have any suggestions for
> such an external devise. My Selectatenna, a Q-Stick +, a homebrew 27"
> Stormwise ferrite antenna (40 turns of Schmarder Litz; tunable w/ varicap), and
> a tunable 2' x 2' home brew box loop do not seem to add any improvement in
> S/N over the entire varicap tuning range; however, all of these work well
> inductively with my E5, Sony 2010, or Grundig G6--the big ferrite in
> particular.
>
> I would like to make an outboard inductively coupled booster for these
> little 310/380 wonders but am not sure how to proceed. A Spring trip to the
> Pacific Coast of Costa Rica is planned--would like to do some TP dxing from
> there, and like all the rest of us radio nuts, I'm a little greedy for more
> RF!!! Any thoughts you might be able to share would be deeply appreciated!
>
>
>
> Raph Pollock
>
>
>
> y
>