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  2. Guy Atkin's Independent Testing of PL-380 7.5" Loopstick

Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick

Pollock,Raphael E <rpollock@...>
 

Hi Jim!
 
Yes, it is the old BAX-1. This whole project begain two years ago when i was able to snag an Eton E1 for $225 from the Circuit City melt down of November 2007. I was interested in the E1 not only because of the various tuning features (PBT, ECSS, Synch, etc.) but especially because it did not have an in-board ferrite bar antenna--a looper's dream machine. So I basically took  something from the monster ferrite bar article co-authored by John Bryant, what I could glean from inspecting the Q-Stick antenna coupled with reading some old IRCA articles, some of the ultralight files, and some of Joe Carr's writings--I know very little about radio theory but sure like to tinker around--a nice use of my hands as compared to performing cancer surgery, which is what I do by way of earning my keep. It was really fun to experiment with the various windings and wires--the plumbing dept. @ Lowe's got very familiar with me as well, what with all the PVC piping and end caps I bought!  The Bax-1 adds mucho red dots on my 2010 and essentially doubled or triples the S/N on the E1.  Most of the time it amplifies the noise as much as the signal, but for the occasioanl signal it can help over and above the antenna being connected directly to the E1, bypassing the BAX-1 (which is housed in a little Radio Shack aluminum hobby box). It will make for a nice mobile unit, but I  am doubtful if Homeland Security will let me take the ferrite bar antenna on board an air flight--it has the heft and size of a hard ball bat. The alternative might be to buy a fishing rod padded case and ship thru as luggage.
 
I spend a fair amount of time in Tel Aviv, Israel and the Mediterranean shore is only about a 10 minute walk from where I stay.  The barefoot 380 has been useful to receive a bunch of European stations (> 10 countries so far without even trying when I was there for several days last week), and so I am eager to take the E1/27" ferrite/BAX-1 with me some time. One of these days I'll get around to taking photos of this set-up and downloading 'em as a file.
 
Thank you for all you are doing on behalf of our wonderful hobby!!!
 
Raphael Pollock
From: ultralightdx@... [ultralightdx@...] On Behalf Of jim_kr1s [jkearman@...]
Sent: Thursday, February 11, 2010 2:36 PM
To: ultralightdx@...
Subject: [ultralightdx] Re: Guy Atkin's Independent Testing of PL-380 7.5" Loopstick

 


--- In ultralightdx@yahoogroups.com, "Pollock,Raphael E" wrote:
>
> Hi Jim!
>
> Do you know of any plans for the regen pre-amps that you mention in text below? It would have to be an improvement over my old BAX-1, a one transistor kit from the mid 1980s that is a broad band preamplifier...

Is that BAX-1 the old International Crystal amplifier? Meant to ask. A regen preamp might be an improvement, but it may not be necessary. I don't know of any published circuits, would like to get a look inside the commercial one.

In a tuned circuit where the inductance is fixed, the reactances increase as you go higher in frequency. A regen made with, say, a 240-uH coil and a 365-pF cap, can be hard to manage at the high end of the band, but very mellow at the low end. That's why I split the band on my receiver. I wondered how they managed that on the commercial antenna-preamp. Assuming you don't need extremely high selectivity (the antenna probably doesn't have to provide anywhere near the selectivity you can get with a regenerative circuit), you could swamp the tuned circuit with resistance and still get lots of gain, and reasonable selectivity.

I should look into this a little more. When I was cogitating on it, I was thinking of something that could be remotely located and tuned. You'd definitely want to use it with a ferrite-rod antenna to reduce hand effects. But an experimental version tuned with an air variable wouldn't be hard to whip up. I do think it would be more useful with older receivers, than with the latest high-gain ULRs and standard portables, which already have lots of front-end gain.

73,

Jim, KR1S
http://qrp.kearman.com/ 
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