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 Post subject: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Wed 16, 2018 7:23 pm 
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Location: 94502
Hi -

I have a real nice Crosley XJ, which I finally checked out and powered up last night. It has 4 01As, which serve as an RF amp, a detector, and two audio stages. There is a filament pot for each tube, plus a pair of big dials which operate variable capacitors, and finally a 5-position switch to select different antenna coil taps.

I have not checked the two xfmrs nor the actual values of the lone capacitor and grid leak - but it was sold to me as the xfmrs being good and I have no reason to disbelieve that yet. Tubes are all good.

BUT...how do I tune the darn thing? I was able to get two stations, only, and quite well - but not the station I want. I'm in an urban area, and using an inside tabletop loop with about 100' of wire. My understanding is that the taps select the frequency range and then you monkey with the two variable caps to select and clarify the stations, and that the pots just serve to increase audio output. The detector tube's pot needs to be watched to prevent regen squeal, too, right?

Selecting different taps does make a difference, although I can tune one of the stations again - although much weaker - using a different tap.

One station is at 1100 kHz and the other is at 1550. I want to listen to ballgames on 680. Any help, please?

Thanks!


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Wed 16, 2018 7:48 pm 
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Location: Massachusetts
I would check the value of the grid leak to start off with, as these can increase in value over time.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Wed 16, 2018 8:01 pm 
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Thanks. What is the effect of a value change for the grid leak? Lack of sensitivity, or...?


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Wed 16, 2018 10:54 pm 
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Grid leak could impact sensitivity in a regen. I thought that the Crosleys had a regen control that was like a "throttle" that you moved in and out for feedback. On my Crosleys, you can utilize both that and the filiment control to adjust detector feedback and gain. Also cannot speak to using a loop antenna versus a more typical wire and earth ground. The antenna can have an impact on tuning range of the detector if there is no RF stage. You say there is an RF stage, which should effectively isolate the det. from antenna, for the most part. A combination of the tap setting and tuning cap sets the tuning range. Whatever tap has the most inductance or coil should tune the lower frequencies.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Wed 16, 2018 11:07 pm 
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Actually I went to a website and it appears your set is a basic TRF type of arrangement, without a regeneration control. At that site found these instructions for the "X" which seems to also be applicablle to XJ type radios. http://www.crosleyradios.com/battery-se ... ctions.pdf Site also has wiring hookups for your radio. So with no extra gain from regeneration, just an RF stage, you might be in need of a more substantial antenna with that set. And pretty good ground. It mentions low B Voltages if you are using a 200 type tube for detection. That is not as critical for an 01 type tube, in that over voltage might be detrimental to a soft detector tube. So you need all the help you can get to get more distant stations, and thus a bad or weak grid leak has impact. A loop antenna might be insufficient in that design. BTW the peepholes are useful for the one amp type tubes, the later ones best not "burn brightly" or they will burn quickly! IF you are using a 6 volt battery, then, keep an eye on your filiment voltages, and be sure those rheostats have the range or drop to keep your filiments 5 volts or less, maybe 4 1/2 with strong tubes.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Thu 17, 2018 1:20 am 
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It may not tune the entire AM band. It was a very basic, early radio.

Pete

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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Thu 17, 2018 2:32 am 
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Surely it would tune 680, since Crosley's flagship station, WLW, is at 700AM

On most TRF sets, turning the knobs to the right increases the frequency. So, start with them all the way to the left.

Also, you should be able to interpolate a bit of the separation of stations by the two you CAN get.

Also, I am pretty sure you want the tapped coil co be of maximum effective size at the lowest frequency range.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Thu 17, 2018 2:42 am 
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Yea, if he was anywhere near Cinn, he would not have a prayer of hearing a 680 station with that radio!


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Thu 17, 2018 2:58 am 
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Thanks very much for all the kind responses. The Crosley "X" instructions were my starting point, but the XJ is different in a few ways, like the number of coil taps selectable: 5 not 7. One major way is that it runs a "C" voltage where the X does not. I guessed and used 4.5v for that. The XJ can run up to 100v B+ as well. I'm using an ARBEiii at the voltages specified by the chassis labeling, plus the A voltage at 6.2v.

Although I called the antenna a loop, I have only one end connected, so it's actually a 100' wrapped-around-some-sticks longwire. The set is well grounded, too.

I sure wish I remembered the vacuum tube stuff I once knew - enough to pass the Advanced Class ham radio license test using it in the early 70's when I was 13 - but alas, I do not and must thus ask these dumb questions.

I'll check the grid leak value and play attentively with the coil setting at largest size. This thing has those funky book-type variable capacitors...so should the lowest frequency be when the plates are furthest apart (like when a regular cap is unmeshed) or closest together (like when a regular capacitor is fully meshed)?

What's really puzzling me is the way it pulls in only two seemingly random stations. They aren't the two strongest around here, they aren't necessarily in a certain frequency band to which the set is limited, and there is not a hint of any others no matter how faint.

The extrapolation thing doesn't seem to work, but maybe if I find a third station a pattern will emerge.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Thu 17, 2018 5:29 am 
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The lowest frequency will correspond to the book capacitor plates being tightest together (greatest capacitance). It's a good idea to keep a written log of dial settings v station frequencies received. Keep hunting and experimenting, and once you are able to find three stations at different frequencies you probably will be able to start building a look-up table or graph that sort of predicts settings for others. It may (likely will) not be a linear function. I have an XJ as well ... a neat old set.
R/ John


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Thu 17, 2018 7:40 pm 
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Grid leak measures at 555k...and does a low value reduce sensitivity? I understand it ought to be between 2-5 megs.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Thu 17, 2018 11:29 pm 
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Seems low to me. Is there any label on it that would indicate what it should be? I assume you removed it from the radio to measure it. I If you can lay hands on a standard resistor in the 2-5 Meg range, should be easy enough to hook it to the holder and see what happens. There may not be a particular optimum value of grid leak. Depends on the detector, and circuit and such. They actually made ones that were variable as it was recommended at the time to try different ones for the maximum sensitivity with a given detector tube. I think 1 meg increments is sufficient, I don't think smaller changes of the value will be audible. The value it is now is well below any recommended value I have ever seen for a 20s radio. You might even benefit some from swapping all four tubes around to see if one is a stronger or more sensitive det. Assuming you know all the tubes are reasonably strong. Certainly trying different tubes in a regen circuit has an effect, YMMV.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Fri 18, 2018 1:15 am 
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Hi Peter,

Refer to the schematic here:

http://www.nostalgiaair.org/pagesbymode ... uto,-14,29

Use a 50 to 100 foot antenna extended out from the radio, not coiled into a hank. Use a good earth ground, not the home electrical system. That will insure there is proper RF circuit at the antenna for the series tuned input.

Set the ARBE-III filament voltage to 6 to 6.6 volts, that is the value of a fully charged auto battery that would have been used in the radio. Use at least 18 ga wire if the ARBE is several feet away for the filament leads. The rheostats provide the voltage drop and generate bias for the tubes, so for the correct bias

The radio has a tuned RF stage that is not neutralized, that means to the user, crank up the RF filament rheostat until the radio squeals from feedback in the RF stage, then back off.

Measure the grid leak out of the radio, looking for 2 to 8 megs. The higher the grid leak the more sensitive the detector. If the grid leak is too high it will cut off the detector and cause a putt-putt sound as it cuts off, discharges and repeats, use a lower value.

If the grid leak is really out of whack it can be temporary jumped with a modern part. Save the old leak as often it can be "stuffed

In this radio the detector grid coupling condenser is connected to the plate circuit of the RF tube. If it is leaking DC it will drive the grid positive and greatly de-sensitized the receiver despite the grid leak. If that cap is not marked it should be .00025mf, A modern silver mica can be tacked in for test until a good used vintage cap is found. If you want to test the cap live, pull the grid leak, leave B+ on, filaments off. Attach negative lead of a VTVM or a DVM to the B- and the positive lead to the grid of the detector tube. If the cap is leaking there will be a positive voltage present. Confirm the load of the grid leak by placing the grid leak back in circuit. The leaking cap voltage should drop, if it is a severe leak it may not drop much...

That should improve reception.

Chas


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Fri 18, 2018 1:29 am 
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Thanks!! Will try soon and post results.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Mon 21, 2018 7:34 am 
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I put a 2.5 megohm grid leak in it and put the recommended 250pf cap in parallel with the existing old one because I can’t find my soldering iron to detach the old one yet.

Same two stations. Plus lots of weird other noises - heterodynes an crosstalk.

I’ll do better on the cap and the antenna soon, but I need guidance on the RF and detector stages. What settings should I start with? Each one makes weirdness when I turn up the filiments too high but I don’t know any rules of thumb for setting them properly.

Thanks.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Mon 21, 2018 2:25 pm 
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Don't know if it would make any difference but I don't see any advantage in putting that new cap in with the old one. You are maybe just doubling the overall capacitance there. Those mica caps get a high resistance leakage usually when they start going bad. Therefore it may be just an extra resistance inside it in parallel with the grid leak. Possibly low enough not to matter in that job. I gotta tell ya, some of those early radios have a tough time n the modern environment. They were usually installed with a 50 or 100 foot longwire outside up high off the house, and stations were not numerous or strong, as most broadcasters were not very powerful back in the early 20s. Lot of 100 watt stations, for instance. Maybe some big 500 watters around. I have a 1 KW AM a couple miles away from me here in town. Thus I do not listen to my BC regens very much during the day, as that station bleeds all over the dial in the background until their sunset shutdown. One of these guys that has a comparable non regen receiver like that might be able to give you better advice, I do not have any working 20s TRF types right now. Got one, but all the trans and chokes are bad in it.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Tue 22, 2018 8:57 pm 
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Busterdog - My main focus is 20's radios and I agree with Chas and Wazz, you need a long antenna put up as high as possible (attic?). Not likely the mica capacitor is bad since that very rarely happens. If you have a good grid leak, you don't need the extra cap.

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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Tue 22, 2018 10:02 pm 
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Location: 94502
I'm thinking that the better antenna will overload the front end, here in the crowded band of an urban area, but I will definitely try it. None of my other battery sets have this issue, and work fine on tabletop antennae, but they are all 3-dialer TRFs.


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Tue 22, 2018 10:17 pm 
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Joined: Dec Mon 05, 2011 1:10 am
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A few suggestions:

>Improve the antenna, as already suggested by others. Even 20 ft. or so up near the ceiling should be better than
100´ wrapped up in a coil
>Use 20 to 30 V B+ on the Detector and ~45 V on the RF and AF amplifier stages.
>Do NOT use any C- bias at all; tie the C- binding post to the A- post.
>Plug your phones into the panel jack, cutting out the second audio stage ... you don´t need it for headphones, and it
just introduces more distortion and one more stage for things to go wrong.
>Set the left-hand dial somewhere in the middle of its range and the tap switch on the second stud from the left.
>Set the filament rheostats to give right around 5.0 V under operating conditions.
>Adjust the right-hand tuning dial till you get a station. Then adjust the left dial for maximum loudness (you may need
to also change the tap switch setting to get the best volume).
>Move the right-hand dial clockwise a few index numbers (increasing the reading) and then do the same with the
left knob. You SHOULD start to pick up another station at a lower frequency. Keep adjusting till you get maximum
volume from the "new" station.
>Then, keep adjusting step-wise as per above, and you should keep bringing in stations with lower and lower
frequencies till you get the one you are looking for. If you note down the optimal settings for each station as you go,
you will have a pretty good tuning chart for your radio / antenna setup.

NOTE: I THINK I have the directions right: clockwise to close the "book", but I MAY have it exactly backwards, in which case, just make your dial adjustments counter-clockwise instead of clockwise as you go.


^^;;^^


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 Post subject: Re: Crosley XJ (and probably other early Crosleys) Tuning?
PostPosted: May Tue 22, 2018 10:18 pm 
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Yea, sounds like your 3 dialers have better selectivity in relation to the Crosley. It was designed to be an economical price point radio when the radio world was quite different than today. A regen is probably vastly better for selectivity except on really close strong stations, like I experience here. Certainly the antenna affects the tuned circuits in your radio front end. As they got their performance with a specified sort of antenna and something else might not do as well such as a loop antenna. Noticed the first tuning cap is in series with the antenna. So the capacitive aspect of the antenna probably is a factor in how well that tunes. Not many(if any) people were surrounded by lots of multi kilowatt stations in 1923. So you will have to have a shorter antenna so the strong locals do not overwhelm the set but you need more antenna for out of town stations, but then bleedover might be the issue. IF you had a modulated signal generator it could help you find stations or what the ranges are.


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