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Message |
    
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1440
Registered: 9-2004
| | Posted on Monday, April 17, 2006 - 11:51 pm: | 
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hi paul,
thanks for taking the time to read this:
i currently run a sangean ATS818 for shortwave listening.
as you probably know; there is only an 1/8" jack for the external antenna input.
would it be OK for me to run 50ohm coax from my "inverted L" antenna to an 1/8" plug?
is the ground on the jack in the radio even connected to anything?
is there a better way to feed this coax into the radio?
i dont mind putting a hole or two in this radio one bit!
i will hopefully only be using this radio for the next few months, as i am currently hunting for a DX-302 receiver. (i have heard good things)
what do you think of this receiver?
thanks for any advice you can offer,
im not afraid to experiment with this,
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1317
Registered: 8-2002
| | Posted on Tuesday, April 18, 2006 - 9:43 am: |
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The center of the 1/8 plug is hot and the outside of the plug is ground, just like a regular coax connector. Coax is the way to feed it!
The DX-302 is one of my all time favorite receivers, and an excellent choice. It takes a bit of fiddling to get something tuned in, but it is (in my opinion) the highest performance receiver under $100. Obviously, they don't make these anymore, so you will buy one used. Be careful since many of these are getting dried out electrolytic caps about now. I recapped one last year and it only took about half a day. Alignment was easy.
99% of the people who own these do not sell them unless something goes wrong with them.
If you choose to purchase something of current mfg., check into the Eton E-1. People have been raving about this radio. My favorite would be a Yaesu FRG-100B or Icom R-75. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1450
Registered: 9-2004
| | Posted on Tuesday, April 18, 2006 - 10:01 pm: |
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right on!
thats what i did! i made a 6' jumper out of rg8x and put a PL259 on one end, and a shielded 1/8" jack on the other end.
connected it to the antenna coax with a barrel connector, and voila!
it works.
why does the external antenna jack on my sangean ATS818 say "AM ext. ant." and not just "ext.ant."?
getting lots of BCB interference as i live close to an antenna (1460 sports radio).
can i build a notch filter, or is there something better for this?
i asked you this in both threads so dont feel like you have to answer twice!
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1321
Registered: 8-2002
| | Posted on Wednesday, April 19, 2006 - 9:31 am: |
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It says AM EXT ANT because it does not do anything for FM band on your radio.
Yes, you could build a notch, but it won't really fix it, although it will really help. You have simple front end overload. You need a variable attenuator.
The good news is, the DX-302 has a preselector and it will NOT have any trouble with that nearby AM.
Or, you could invest in an R390 or R390A (do a search) and the interference will be gone for good. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1456
Registered: 9-2004
| | Posted on Wednesday, April 19, 2006 - 5:06 pm: |
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thank you paul for sticking with me through this project.
i am happy to say that last night i sat in front of my shortwave radio for HOURS! like i havent done since i was younger.
this antenna works so well!
i was picking up numbers stations, and havent heard those in a long time.
i saw a product in the univeral radio catalog for about $60.00 that seems pretty cool.
it cuts out anything below 1.7mhz.
i will do the search and see what you are describing.
thanks again, im officially hooked!
any links for a current shortwave "TV" guide?
matt |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1458
Registered: 9-2004
| | Posted on Wednesday, April 19, 2006 - 7:27 pm: |
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wow!
the R390A is amazing!!!
talk about a restoration project, that radio looks intimidating!
well, i would love one, but unless i strike it rich, or someone around here doesnt know what they have; i doubt i'll ever get a chance to use one.
the re-cap and alignment on the DX302 seems a bit more my speed!
i am looking at the Par BCST HPF. which is a little unit that will block out the AM BCB.
can you tell me whether i could make my own, and what i would need?
or is this thing complicated?
it looks so small, it just seems like there cant be much to it.
thanks again, and i am very jealous of your noise floor. (-143db!? GEEEEZ!)
matt |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1182
Registered: 6-2004
| | Posted on Wednesday, April 19, 2006 - 9:32 pm: |
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You could use a preselector/tuner/amplifier. I have a very cheap one that I bought at Rat Shack years ago, and it works surprisingly well for SW and even the AM BCB even thought it wasn't marketed for that purpose. It plugs right into the AM external antenna jack of my DX392/ATS818CS and does wonders for SW reception with the included 3' whip or in conjunction with a longer wire.
I also have a 20' antenna that unwinds from a reel, and it works pretty well, but I think the DX392 is too sensitive to use an antenna longer than 20'. I get overload and desensitization even with the 20' antenna at times.
My TS450SAT is a far better SW receiver than the DX392. It also does a fine job on AM BCB where most HF rigs have sensitivity problems due to filtering. Rather than investing in a stand alone SW receiver, you might want to find a nice HF rig if you intend to eventually be licensed for HF work. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1459
Registered: 9-2004
| | Posted on Wednesday, April 19, 2006 - 10:44 pm: |
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here's a high pass filter design that i found online.
seems very simple to build, but im not quite sure on winding the inductors.
the circuit consists of three ceramic disc caps in series, .002, .001, and .002uF respectively.
before and after the second cap, are two inductors going to ground. 3.3uH each.
the instructions say to wind the coils on torroid forms with 26 turns of small wire.
do these have to be torroids?
can i just use 3.3uH inductors bought from the electronic parts store?
if i must use the toroids; where can i get some?
here's what they say about the inductors:
The inductors are both 3.3 µH, so can be made with toroidal cores. If the T-50-2
RED cores are used (AL = 49), then 26 turns of small diameter enameled wire will suffice.
Or if the T-50-15 RED/WHITE cores are used (AL = 135), then 15 turns are used. The
circuit of Fig. 3 produces pretty decent results for low effort.
so what do you think?
looks pretty simple to me,
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1324
Registered: 8-2002
| | Posted on Thursday, April 20, 2006 - 9:56 am: |
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KV, Most R390A owners never go inside the radio themselves. There are many qualified radio experts out there that ONLY work on these radios.
I have done some work on both of my R390A's, and it really wasn't difficult at all. In many ways, it was easier than a DX-302. Since the R390 and R390A's are all modular, you just remove the module you want to work on and resinstall when done. All the parts are big and easy to spot. The 'magic' is in that gear train. As long as you don't have to disassemble the gears, you will not cuss at it.
The alignment is really simple. Time consuming, but really super simple. And, you end up with a radio that will still work after a nuclear or EMP blast! Literally. Assuming you were not so close that you got vaporized....
As for filters, yes you could easily build a filter, just as Matt described above. You can also purchase them. Universal Radio sells units that are tuneable and also simple BCB notch types. The good news is, most all SWL stuff is 50 ohms, so your existing coax and antenna hardware will not become obsolete when your station gets more and more fancy. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1460
Registered: 9-2004
| | Posted on Thursday, April 20, 2006 - 6:52 pm: |
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hollowpoint, thats why i want to get the DX302.
lots of bang for not much bucks.
i will be getting an HF rig, but i will be spending upwards of 600 on it, and wont be able to do that for a while.
with CB as boring as it is and will be for a while, i want to at least have a decent set up for SW listening.
i have a 70' +or - antenna, and while i do get overload on the low MHZ, i believe that it is just BCB interference causing the overload.
i am much happier with this antenna than the others i was using.
833, still curious about those chokes?
can i buy some, or do i have to buy toroids and make them?
any input?
thanks
matt |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1465
Registered: 9-2004
| | Posted on Thursday, April 20, 2006 - 9:19 pm: |
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they sell toroid cores at Fry's!!!
i couldnt believe it!
i stopped by during my break to get a PC mic, (which i forgot in my excitement! im soooo embarrased!)
they had the T50-2 cores, so i bought them, a few others to play with, and some 24ga. magnet wire.
i am about to start winding my first toroid coils,
and cant wait to try the new filter.
now if rad shak and frys would restock some SO-239's i'd be set. darn obsolescence!
matt |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1186
Registered: 6-2004
| | Posted on Thursday, April 20, 2006 - 9:34 pm: |
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Good luck with the DX302. I considered buying one at one time, but decided against it after doing more reading and evaluation of it's features against vs. my needs. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1468
Registered: 9-2004
| | Posted on Saturday, April 22, 2006 - 9:12 pm: |
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i cant believe that it actually worked!
i built the high pass filter today and finished it about 20min. before i had to leave for work.
darn!
from the little time i did test it, it worked pretty darn good.
there was still lots of noise on the lower MHZ but the voices were gone.
im not sure what the normal noise level is around the 80m portion of the band, as i have never been able to listen down there much.
i found a station on 5975 and i tried the filter in and out of line.
the filter seemed to actually increase the signal of the station !
not sure if this was actually true or not, again i only had 20 mins.
but without it i cant listen to 80m and with it, i can.
so far i am very happy.
just ordered the new passport to worldband radio book.
later,
matt |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1189
Registered: 6-2004
| | Posted on Saturday, April 22, 2006 - 10:17 pm: |
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Using the filter could increase the net sensitivity of the lower frequencies if the receiver was being desensitized by a powerful AM BCB station. From your description it sounds like it went well beyond desensitization to the point of intermodulation.
Lots of HF rigs have attenuation on the AM BCB so the sensitivity of the lower bands is not affected. Specifically, the TS440 has a modification to restore full sensitivity to the AM BCB.
Just curious - Did you buy the inductors or wind them yourself? |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1191
Registered: 6-2004
| | Posted on Saturday, April 22, 2006 - 11:01 pm: |
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DOH! I guess if you bought torrids you did wind them yourself. I missed that post. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1472
Registered: 9-2004
| | Posted on Sunday, April 23, 2006 - 1:06 am: |
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i felt so lucky when i walked through fry's electronics, and i actually found the toroids that i needed.
that never happens to me!
yeah, the interference was really bad.
if im on my roof, i can see the antenna.
its about 5-7 miles away.
that, coupled with this receivers low dynamic range basically crippled it.
i had tried lots of longwire antenna experiments with this radio, and they all had the same downfall. if they were sensitive enough to work well, they picked up the BCB signals.
i am learning alot about how the dynamic range of the receiver relates to spurious emmissions.
these porta receivers dont do too well in this category.
cant wait to play around with it later tonite, when its nice and quiet.
its 10pm here, and i dont get off for another three hours,
cant we speed the show up?!!!
matt |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1193
Registered: 6-2004
| | Posted on Sunday, April 23, 2006 - 10:40 am: |
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There are a few portables that are actually good overall radios, but most are a pretty serious compromise. The only one I can think of that really isn't much of a compromise is the Sony ICF2010 - especially after modification, and there are TONS of performance mods for the 2010. I like my DX392/818CS, but I wish I'd have bought a Sony2010 when I had the option. I'd buy one now, but it would be used, and I can't believe how much they go for on auction sites! Their replacement must not be very good, or as modifiable.
If you really want to play with the 818 you probably want to buy a preselector/tuner to help with selectivity. Even the cheap one I bought (Radio Shack 20-280) REALLY helps my DX392/818CS. The amplification doesn't hurt either, especially when you can't use a longer antenna and have to use the included whip. It even works on the AM BCB and helps to dig out a weak station adjacent to a strong one running more than 100% positive modulation. If I'm really trying to listen to the AM BCB I use my Select-A-Tenna. One day I'll get around to making my own bigger and better AM BCB loop antenna about the size of a box fan, but for now the Select-A-Tenna works great.
I can't tell you how much better my TS450 is than the 818CS for general listening. I'm spoiled with all of the features and especially the filter options. I just can't listen to anything else when I'm in that room or even my entire apartment thanks to the amplified speaker I use.
Used HF rigs don't have to be expensive. I paid about $800 for my TS450, but it was NIB and came with a NIB MC-85 desk microphone that sold for $150 when they were still being made. The gentleman who sold it to me sent along his original purchase reciept and the total was over $1400. It took me more than a year to get a deal like that, but I wasn't in a hurry and I got lucky.
I've seen used HF rigs sell for very cheap prices. Cheap enough, that I've been looking for another TS450 or something better to use for SWL. I've owned a TS140 and TS680 and they're nice rigs too. A little more basic than the TS450, but still very good receivers and they have something that the TS450 doesn't - an analog S-Meter. I'd love to get a TS850, TS940, or TS950, but my budget probably won't allow that, and the TS450 is triple conversion with lots of features, so it'll easily fit my needs. The only thing it's really missing for SWL is synchronus detection, and I've gotten good results by switching to either USB or LSB when the signal starts to fade. That also works when you have a strong adjacent station. I switch to the sideband that is opposite the strong signal, select a good SSB filter bandwidth, and/or shift the IF frequency a little. |
Tech833
Moderator
Username: Tech833
Post Number: 1329
Registered: 8-2002
| | Posted on Sunday, April 23, 2006 - 11:11 am: |
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The 450 is one fantastic receiver, I doubt you will find one better for under 2 grand.
I have my old trusty TS-440S and I use it for SW listening. It has the same receiver as the Kenwood R-5000 and your 450. Out of all the SW radios that have come through my shack (over a hundred), the 440 beat them all. Drake, Icom, you name it. Yes, I bypassed the AM BCB attenuator on mine. The nearest AM BCB XMTR to me is about 30 miles.
Sycronous AM is nice, but not mandatory. If you want to do any real serious AMing, you need an R390A or Ten Tec RX-340 type rig. Anything less than that will not make a noticeable improvement over your 450. |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1195
Registered: 6-2004
| | Posted on Sunday, April 23, 2006 - 1:22 pm: |
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Thanks Tech833. Wow - over 100 SW radios? Were you evaluating them professionally or just looking for a personal radio?
How do you like the 455kHz AM filter in your 440? I read that the AM filter is less than desireable on this page:
http://www.somis.org/440.html
I've thought about changing that filter in my TS450 with a CFS455H to get a better shape factor. I don't know if I want to bother with changing the filter on the board, or making up a filter board to use in the 455kHz optional filter slot. Any thoughts? |
Tech833
Moderator
Username: Tech833
Post Number: 1331
Registered: 8-2002
| | Posted on Sunday, April 23, 2006 - 5:26 pm: |
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Yes, over a hundred radios. Some were just here for review for one magazine or another, most were here because I bought them thinking it would be a good radio. After comparisons and true bench testing, I seldom keep a SW radio that does not perform as I think it should. My friends and family are sick of being given SW radios!
I like the filters on the 440. I have no complaints. You know, sometimes people need to 'mod' their equipment just so they feel smart. Keep that in mind when you read that kind of stuff. Hams are the worst offenders of the 'know-it-all modification' procedure. Just mod something until it barely works, then sell it at a swap meet and buy a new one that does work. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1474
Registered: 9-2004
| | Posted on Monday, April 24, 2006 - 11:13 pm: |
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have been having fun with my new antenna.
last night, just for kicks; i put the sangean on 27.185 to listen to the locals bark at eachother.
it was interesting since i know roughly where everybody i heard was located.
im wondering if what i noticed was only true for short distances or if it would also be true for the DX stations.
my antenna (inverted L) seemed to have a null towards the north.
the far horizontal end of my antenna is pointed south.
there were two guys talking, and one guy trying to key on one of the others. (sound familiar?)
one guy is about 25 miles south of me, and the other guy was about 10-15 miles to the north of me.
the troublemaker was also north of me at a distance of about 10 miles.
on my astroplane connected to my 2000gtl, mr. south hit me at S-5, mr. north hit me about S-7 and the troublemaker also at about 7, so he was getting over mr. south.
on the sangean with the L antenna, both guys to the north of me were not registering on the meter, but mr. south was up at about S-3.
when the troublemaker would key on mr. south, i would get all heterodyne in the 2000, but i could hear mr. south on the sangean just fine.
to me this means that my antenna favors signals from the south.
is this true?
is it still true as the stations get further away, or is this just a short distance phenomenon?
i would much rather put the null towards the south if this is the case.
any advice or input is appreciated.
PS-anyone like the yaesu FRG-7000?
looks neat to me,
matt |
Tech833
Moderator
Username: Tech833
Post Number: 1333
Registered: 8-2002
| | Posted on Tuesday, April 25, 2006 - 12:22 am: |
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That is 'normal' when using a long inverted L on real high frequencies (like 27 MHz.) On lower frequencies, it is omni, but as you get real high (where the wire is way over 1 wavelength) then it becomes directional to the direction the horizontal part is pointed.
My inverted L is directional to the SE on CB, so I hear a lot of Cuban CB traffic. |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1197
Registered: 6-2004
| | Posted on Tuesday, April 25, 2006 - 11:17 am: |
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I was considering the mod because I'm always looking for a little more adjacent channel rejection. I just bought a TCXO for my TS450, so whenever I get around to installing it, I may solder in the CFS455H just to try it out. I've thought about trying one in a CB too, but I really don't spend much time on AM.
I don't make modififications just to fiddle with the radio. If I think a modification has merit I'll try it out, but most of my radios are stock and will probably remain that way. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1475
Registered: 9-2004
| | Posted on Tuesday, April 25, 2006 - 10:38 pm: |
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thanks for the info 833!
matt |
Hollowpoint445
Senior Member
Username: Hollowpoint445
Post Number: 1215
Registered: 6-2004
| | Posted on Sunday, May 07, 2006 - 12:17 am: |
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When you get the DX-302, tell us how you like it. I'm thinking of getting a SW radio for a fairly specific use, and I might go with a DX302 because of it's bandspread feature. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1529
Registered: 9-2004
| | Posted on Sunday, May 07, 2006 - 4:14 pm: |
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no prob!
you know me, i probably wont be able to shut up about it.
in looking for a shortwave radio,i found universal radio's used photos section to be an invaluable resource. seems like they've sold one of everything.
i was also looking at the yaesu FRG 7000, which also uses the wadley loop system, and seems largely the same as the DX302. i think it looks cooler too, but i found a great deal on a 302 first.
i'll post for sure when i get it.
matt |
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