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AK 55 fixed




 
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Author Topic: AK 55 fixed  (Read 6246 times)
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Carl WA1KPD
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« on: August 13, 2006, 08:02:49 PM »

Filter cap miswire
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Ed-VA3ES
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« Reply #1 on: August 14, 2006, 02:34:58 PM »

What's the AK stand for, Alter Kacker?
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Carl WA1KPD
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« Reply #2 on: August 14, 2006, 02:59:31 PM »

Atwater Kent
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k4kyv
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Don
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« Reply #3 on: August 14, 2006, 03:18:38 PM »

Interesting.  Mine has a different style cabinet, with round opening for the speaker.  Some idiot in years past cut out the wood grillwork with a  saw, so I just removed the remains and now it has a plain round hole with grille cloth.

Haven't fired mine up in years.  Have used it as a bedside table since before my oldest kid was born (he's now 26) but everything is still there and theoretically should run, but my original filter caps are probably bad by now.  I recall very poor selectivity at the top end of the band.  That is normal with TRF's.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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The Slab Bacon
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« Reply #4 on: August 14, 2006, 03:19:25 PM »

I also have an A-K 55 in my collection, mine however is the "sardine can" style. Of the older AK's that is one of the easier ones to repair. the filter caps and choke are potted seperately from the transfoma, in a seperate can slid into the power supply box. You can just slide it out, toss it, and assemble the needed components into the power supply box. (unless your a real man and like the smell of melting pitch) The earlier sardine cans HAVE to have the pitch melted out to replace the caps, I have done a dozen or so in the past. I have actually developed a technique for getting them apart WITHOUT damaging the transfomas.

The 55 is a screen grid TRF type with 24A's in the front end and P/P 45's for the outpoot. If done properly they play pretty nice! I guess I have a warm spot for old AK's In my collection, I have a 20, 30, 35, 38, 46, 52, and a 55.
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Carl WA1KPD
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« Reply #5 on: August 14, 2006, 04:20:59 PM »

I recall very poor selectivity at the top end of the band.  That is normal with TRF's.

Don,

I have several additional 55s that are in bad shape. One of my thoughts was to play with one and by removing some of the coil windings get it to operate as a TRF on 160.

Do you think the sensitivity/selectivity issue you observed a function of the circuit i.e it just will not function well above say 1.5 MHZ or is it a function of the change in the LC ratio as one moved up the band? If it is the latter then getting the coils set right should make a fun little radio
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« Reply #6 on: August 14, 2006, 04:40:21 PM »

Carl,
       I think it is a function of the L-C ratio and the fact that it is only 2 stages of TRF
(the 24A's). You could have much better selectivity with an AK-38. It is all triodes, but it is 4 stages of TRF. My 38 is very hot and quite sharp for a TRF receiver. That may be a better choice. Also be sure to synchronize the tuning caps carefully FOR THE END OF THE BAND THAT YOU PLAN TO USE MOST. This is pretty important as you will find that the tuning spread changes from one end to the other. the various stages dont quite track exactly the same as each other. "Aligning" these radios is usually always somewhat of a compromise from one end of the band to the other. And you will just about always find that they perform better at one end or the other. The "older" versions with individual tuning knobs for each stage somewhat eliminated this problem, but were more of a pain in the a$$ to tune in a station. However they are still a lot of fun to play with. The 55 in the "Pouley Table" seems to be the most desireable to collectors and "conniseurs"
                                                   The Slab Bacon   
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k4kyv
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Don
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« Reply #7 on: August 15, 2006, 10:27:07 AM »

I agree that it's the  L-C ratio.  Also, the tuning rate is much higher at the top end of the band, so that the stations are all bunched up  together, while the lower end of the band has plenty of bandspread and selectivity.  I never tried realigning it; don't listen to AMBC radio that much anymore.  If I can get one of those radios to play beautifully on one or two local stations that's all I need.  The band is such a jumbled up mess these days that you can't pull in distant stations even on a communications receiver like in days of old, let alone on an antique TRF "consumer grade" receiver. 

Remember the station in Elizabeth, NJ that transmitted experimentally on the expanded band 1600-1700 kc/s before they opened the floodgates?  They ran 1000 watts and were heard coast-to-coast.  That's what the entire band must have been like when the AK-55 radio was new.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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« Reply #8 on: August 15, 2006, 10:47:08 AM »

Don,
       One night about 10 years ago I wuz tuning around in what was to become the expanded bcb, somewhere around 1700 kc and found a station playing some of the best cuts of 1960's album rock music i have ever heard on the radio and using a rather wierd callsign. They were even giving out a fone numba for requests!! I called them and found that they were an experimental portable station that was being tested at Ft. George G. Meade in Severn Md. It was being tested before it was to be shipped to Bosnia. They were looking for propapation reports as well. They were on the air for about a week. I was very sad to hear them sign off for good. They really played some great music!! And the DJ's were just normal people that would talk to you on the phone.

If I remember correctly Paul (VJB), Steve (HUZ), and Fred the mopman had gotten in touch with them and were contributing some of the programming towards the end.
They were giving out QSL certs, but i never mailed in for one.

                                                             The Slab Bacon
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Carl WA1KPD
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« Reply #9 on: August 15, 2006, 07:18:51 PM »

Frank and Don

Thanks for confirming my suspicions about te LC ratio.
I agree Frank that the 3 stages would be good but really what I am planning to do is use some 55 donor rigs I have here. My thought would be to put some 6F6s rather then $$$$$$$ 45s in the PP audio out, hiding the 6 V xfrmr in the can that holds the filter capacitors. What I have done in the two I have restored so far is to hide the replacement caps under the chassis and will continue to do so. So I will have the space in ther.

Can you imagine how cool to be on 160 (or 75) strapping away and saying… Rcvr here is an Atwater Kent 55.

Problem is I am long on ideas and short on time. But the fantasy is often half the fun !
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« Reply #10 on: August 16, 2006, 08:05:46 AM »

Carl,
      You might get away with using a modified 55 on 160, but not a snowball's chance in hell on 75. You need all of the selectivity you can get with the qwermers, jammers and other assorted sphincters on 75! Nice thought, though.

                                                                            the Slab Bacon
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WA3VJB
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« Reply #11 on: August 16, 2006, 04:38:17 PM »

Yes, Frank, good memory.
Steve's got photos and details here:
http://www.amwindow.org/pix/htm/ktrk.htm

This spring I happened to be at Ft. Meade on the Abu Ghraib dog handler courts-martial, and was right at the site where the trailers were parked. They now are a pre-screening area for security risks (like the media pack dogs), vehicle inspections, etc.

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« Reply #12 on: August 17, 2006, 08:27:32 AM »

Paul.
       That was a good guess, I thought it was about 10 years ago. What realy caught my attention was the wierd callsign they were using. After reading the article, I remembered that they were IDing as "ABS" and I had never heard an American broadcast station use a callsign that didnt start is W or K. The "KTRK" must have come towards the end. ABS is thecall that I remember. They were quite strapping for a temporary facility! At that time most of the standard BC radios wouldnt tune that high, and most of the listeners were hams using communications receivers. Many of the requests were called in by hams.
                                                           the Slab Bacon
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