Lafayette KT320 2 bands not working

[PLAFETTE]

Hi everyone! I am new here and have a few things I would appreciate help with. I will only post about one of those in this thread.

I have a circa 60s Lafayette KT320 four-band radio,
which I guess you guys like to call a "boatanchor."
I like that description! It really fits this heavy monster!

The four bands are:
.55 - 1.6 MHz (which I finally realized is the regular AM radio band!!! That explains some of the super loud stations I was getting last night with a local sports game broadcast)!
1.6 - 4.8MHz This one works okay. I was picking up some Spanish stations near the 4.8 end of the band

4.8 - 14.5MHz - No signals
10.5-30MHz - No signals.

I bought this a decade or two ago at a garage sale and played around with it for a while back then. Initially all the bands work as I recall - certainly three of them did, if not all four. I had a "Band-match" 4-way antenna for it back then, but no longer have that. As I recall, on at least one of the bands was VERY tricky to find anything even when it was working.


Now, after years of being stored in a closet, the lower two freq bands are still working, but the upper two bands do not seem to pick up signals.

I only had a 15 or 20 foot wire attached to it for an antenna last night when I tried it out again. Even so, I think SOME kind of signal noises would have come through somewhere on those two higher bands, even if not much.

All I got on those upper two bands was the general background sound that I get on the two lower bands when not tuned to any active signal. But no squeals or clicks or what my father used to call "Diathermy."

There does seem to be SOME kind of changing pitch of the background sound as I goes across the dial, but it almost seems to repeat in a cyclic sort of way slowly as I dial across the band.

To try to narrow down the problem: on these two higher bands, the RF gain makes a difference in volume, as does switching to the SSB position on the selectivity switch. But there is just NOTHING "signal-like" anywhere on those two bands.

I downloaded the manual for this yesterday and looked through it. That gives me the "names" of the tubes and their functions. I will list those at the end of this post because I have questions about some of them.

On the lower two bands I sometimes use the Q-multiplier and set selectivity to SSB position to tune some things in better. But loud signals come in on the "REC-AM" setting and without the selectivity being in "SSW."
There is also an "antenna trim" that I frequently adjust a little as I sweep the bands too.

Okay, I am just trying to show that I have some familiarity with how to fool around with the settings on this old radio to hear things on it. Mostly so that you will make better guesses about the problem with this radio.

I have some understanding of basic radio theory, like general principles of tuning circuits for example, and studied a bit about how a transistor amplifies a signal, and I understand the basics of a simple straight-wire antenna.

But I am not terribly practical nor wonderfully technical in my "hands-on" knowledge. My father taught me how to solder and I built a few small electronic kits in my youth.

I don't know hardly any of the many common abbreviations for things that are so often used by Hams. Please try not to confuse me with abbreviations when helping me. I know that SSB is single side-band and I have a basic notion of what that is - and that the BFO (beat freq oscillator) is needed to tune in SSB voice signals. But that's about the extent of my familiarity with these things. I learned that much from my father when he was still alive and he gave me a Heathkit - maybe SB200 or something. Really not very good but with the BFO I was able to pick up some chatter and plenty of East-Asian nighttime radio signals. I would think this lafayette could do as well or better at getting those, but so far it doesn't seem to get much. Maybe I need to get a little more serious about an antenna wire of the right length for the higher bands.

I know it is pretty hard to tell what is wrong with this radio just from what I am able to describe about what I am hearing, but maybe someone can give me some things to try that would help us to sort out what kind of problem it might be.

Here is the listing of the tubes- from the manual I downloaded:
V1 6BA6 RF amplifier
V2 6BE6 Mixer
V3 6BE6 HF Oscillator
V4 6AV6 Q Mult BFO
V5 6BA6 1st IF Amplifier
V6 6BA6 2nd IF Amplifier
V7 6AV6 Detector, 1st AF Amp, ANL, AVC
V8 6AQ5 Audio Output
V9 5Y3 Rectifier

I don't know what the "Mixer" is.


From what I can tell I think I can rule out problems with the RF amp tube, the Q-mult tube, and the ANL and AVC (since those controls work on the two lower bands), and maybe also the audio output tube is okay; since those lower two bands play voice signals.

I would think that the two IF tubes must be working too - or is the IF different for some bands than for other bands???

But what about the HF ( =? High Freq?) Oscillator tube - could maybe that be the problem, since it is the two higher freq bands that do not seem to be working?
And again, I don't know what the "Mixer" is so I have no clue about that.

Thanks for reading through all this. I hope you can give me some ideas!

 

[Moleculo]

Try the higher frequencies (10-30mhz) during the day and the middle ones (4-10mhz) between dusk and night and see if you get anything. Try around 7-8mhz on AM and around 14mhz on SSB (try USB, if it has that setting). Crank the RF gain all the way up.

It's VERY likely that the radio works just fine on those frequency ranges. What you are able to hear in the upper 1/2 of those frequencies you indicated is dictated largely my mother nature. Mother nature also has a cycle that it goes through peaks (lets you hear everything around the world practically) and valleys (you can't hear the guy across the street on some frequencies). We're in the middle of one of those low spots, although it's starting to get better.

I would try different days and time of day and see what you can hear before tearing apart the radio. I bet it works just fine from what you described. BTW, if there is a way to get more wire in the air for an antenna, do that. If you have a tall tree, get some up there, as high as you can. It will make a difference.

 

[PLAFETTE]

Great suggestions!

Thank you so much for these suggestions!
These are going to be very helpful.

I live on a 2nd floor "residential" apartment that
has a balcony. So I am up in the air a bit. I can string
some wire along one or two sides of the balcony,
along the ceiling and have the rest of it inside,
keeping it almost in a straight line.
I just have to be careful that the wire is not conspicuous
from out there down below and about 150 feet away -
which is where the walkway is.

I will check out those portions of those bands at the times
you suggested. I am happy to hear that the radio might be okay.

Those cycles you are talking about - I remember when my father had a CB radio and with just his 5 watt set,
he was getting "skip" from Georgia and other southern states, while he was in Michigan. That would have been in about 1963 or 1965, somewhere around there. He said it was not very common on a CB.

Thanks again!

 

[PLAFETTE]

Band switch problem - but all 4 bands DO work... (I think)

I tried the upper two bands as you suggested today - using REC-AM and no SSB for the 4.5 - 14 MHz band and using Q-Mult and SSB settings for the 10-30MHz band. I did get all kinds of sounds on those two upper bands using those settings, though I have not really heard any "stations" or definite communication transmissions.


I also put my 'antenna' wire up along the ceiling / wall corner with the radio near the balcony door and ran most of the wire up on the ceiling of the balcony. It makes an L-shape rather than straight line but that is the best I can do if I have it mostly outside. I definitely notice a huge drop of of radio volume if I disconnect the antenna so it must be doing some good.

I went down to the band above the AM broadcast band just to check on things and I did hear a strong station in Spanish language near the high end of that band using settings: REC-AM (not Q-Mult), and no SSB on the "selectivity" knob. I did that because I was not hearing any true communication signals on the 4.5-14 MHz band when set to AM and no SSB.

I did discover that one reason the highest band has been so absolutely "quiet" is until now is that the band selector switch was not making any connection when turned to that band position. (There is a similar but less serious problem on the that other high band that I had thought did not work.

I found that on the highest band, 10-30MHz, if I applied some CCW torque to the knob continuously, then the band would connect. I tried turning the switch back and forth many times between those two upper bands both fast and then very slowly too, and the switch does connect better now on the high band but only when it is just off from it's "rest" position a little. It still "slips" back to the rest position and that band does not work when it does that. I can tell when it happens because the volume goes way down and nothing changes as I turn the freq dial. I can usually get it to connect again for a while but jiggling it a little towards the next lower band position without going all the way to that lower band.

I have not heard any voice signals or definite communication signals on either of those two upper bands yet, but I do hear quite a bit of the usual range of noises and squeals and all that, as I go across the bands. Some places are extremely quiet and some places are more noisy - which I take to be a very good sign.

The 12-14 MHz zone you suggested I try on the 4.5 - 14MHz band is a bit "hotter" sometimes and other times near 14 it is noisier. The upper band is most "dynamic" at the high end near 30MHz, though again, I have yet to hear any real communication signals so I am not 100% sure things are all working properly.

A few questions:
1. Is there a fairly easy way to get that band selector switch to make better contact? It does not work all that great on the other upper band either but is especially bad on the highest (10 - 30MHz) band. I can go inside the case with everything off and unplugged and I would guess I can get access to that switch. I have some of that canned electrical contact spray cleaner. Maybe I could Q-tip some of that on the contacts?

2. I notice that the 4.5-14 MHz band and the 10-30MHz band overlap, yet it does not seem that the kind of "noise" I get in that overlap zone is the same when I go to the same zone on the other band -even using the same REC-AM and no SSB settings both times. I don't understand this.

3. I am not sure about the actual way that the "Band Spread" dial works. I think of this as a "fine tuning" mechanism in which small movements of the dial make much smaller changes in the frequency than similar movements would produce on the main freq tuning dial. Is this a correct understanding or is there something else going on as well when the band spread dial is turned?


Again, thank you for your suggestions yesterday. I feel we have made a lot of progress already.

 

[Moleculo]

1. Is there a fairly easy way to get that band selector switch to make better contact?

You probably would have to open it up and spray some contact cleaner on the contacts. That's probably all it needs. Of course getting at the switch might not be too fun. Hard to say without seeing it.

I notice that the 4.5-14 MHz band and the 10-30MHz band overlap, yet it does not seem that the kind of "noise" I get in that overlap zone is the same when I go to the same zone on the other band -even using the same REC-AM and no SSB settings both times. I don't understand this.

It has to do with how the receiver circuit is designed. In brief, it's sensitivity is probably dropping the closer you get to that band edge, so you're probably better off switching bands

3. I am not sure about the actual way that the "Band Spread" dial works.

That sounds like what it's doing to me based on what you described. I've never seen that radio before, though.

With the upper bands, if you can get the switch working properly, try putting it around 14.200 +/- on SSB during the day. That's the 20 meter ham band. Move the frequency dial around a little bit throughout the day and see if you can find someone. It might be hit and miss but when you get a good propogation day there will be stations there. Especially try it on the weekends. I think it's working and you just need to clean that band switch.

 

[PLAFETTE]

more progress

I did have more success last night. I heard actual voice and music broadcasts on those upper two bands. The 4.5-14 was much more active. I found four or five signals there. On that band I found things at about 10.5MHz, 11.2MHz, and 14.5 MHz.
On a lower band I found the universal time clock station around 5.2MHz (or else it was NOAA weather - I didn't write down which it was, and I found the other one on the cheapie radio).

I only came across one true broadcast on the highest band - 10-30MHz. It was in the CB zone, around 28.5MHz (roughly) and since it came in pretty loud I thought it might be a CBer. It was a private conversation about radio, and I could not get the audio of the other party.

I dropped a wire down to a pipe down below for a ground, but I could not detect any difference whether it was attached or not. That surprised me. I thought a ground would always help reception.


I also went into the manual to get a little more clarity about using the selectivity on the Beat Frequency dial. Turns out I was right about how to use just about everything on this radio, but I had not realized that the selectivity in combination with Q-Mult setting (instead of "REC-AM" setting on "Function" switch) gives a narrower peak - (though the words "Q-Mult" and "selectivity" alone really should have told me that!) - allowing one to select out one frequency when very close to another. It's no surprise I had not figured that out since I have yet to find two signals close together.

One thing I am not completely sure about yet though. On the highest band, 10-30MHz it seems that I HAVE to set the radio with "Function switch" on "Q-MULT" and selectivity on CW-SSB (this switch can be locked on CD-SSB or at other setting, dialed around to change selectivity). If I do not use those settings on that highest band the volume is way to quiet to hear anything no matter what else I set any which way. But on the lower bands - any of them - I can get away without having to set function switch to Q-Mult (I can leave it in REC-AM) and I don't HAVE to have the other in CW-SSB position.


I am not sure why these settings are "band-specific" this way. When I find a good loud signal on the on 4.5 - 14MHz band, I can set it either way - but usually the SSB setting is "too squeally" and hard to get rid of that beat-oscillator noise.

When stations are weaker, (on all but highest band) THEN it seems that SSW (ie using BFO) setting works better - both for getting higher volume and for tuning in the signal better. There is something here that I am not quite understanding fully.


I want to thank you again for helping me / reassuring me about this radio and getting more satisfaction out of it!

 

[Moleculo]

On a lower band I found the universal time clock station around 5.2MHz

That was WWV. It operates on 2.5, 5,10,15,20 mhz.

NIST Radio Station WWV

 

[PLAFETTE]

Did some work on the radio

That was WWV. It operates on 2.5, 5,10,15,20 mhz.

NIST Radio Station WWV

The bandspread tuning dial has been slipping more and more, so I had two reasons for going inside the radio yesterday.

1. I used the electrical contact spray on the band selector switch and now it works much better, maybe even perfectly.

2. I was not at all confident about being able to fix (myself) the slipping bandspread tuner but I took a look at it and the string was not aligned quite right in the large pulley groove. It was "climbing" out of the groove a little. It was easy to slip it back into the groove but upon turning the dial it was still slipping badly. So I used some WD-40 to lubricate every pulley axle and even the variable capacitor "axle" where it turns in it's housing. I was trying to be very careful not to get the WD-40 on the string itself or on the dial that the string wraps around 3 times - and has to "grip" the 1/16 " dial axle (the one being turned by hand). I could not believe that there is nothing on that small axle to help grip the string. Seems like there should be some kind of coating on it where the string is wrapped around it to help it grip better - but there isn't anything of the sort. But, very much to my surprise, simply lubricating all the axles and pulleys got it working smoothly with NO slipping. That really surprised me. It glides along smoothly from one end to the other now.

I am also really amazed that the string that connects the hand-turned (bandspread knob) axle to all these pulleys and the little flywheel and the var capacitor - to drive all the mechanical motion - must be 45 years old and yet it has not lost tension due to stretching/aging!!! It still grips the little axle and everything else well enough to work perfectly! I don't know what kind of string they are using in there, but WOW!

Okay now; those WWV frequencies you gave me help me to get a fix on how far off the tuning dial frequency indicator is. I just had WWV loud and clear at 11.2MHz on the 4.8 to 14.5MHz band. Since WWV is at 10.0 and 15.0, I would guess the "11.2" I am seeing is probably the 10.0. That is quite a bit of "slop" - or whatever the technical term would be for this descrepancy. (I did have the "bandspread" dial set to the far right end as the manual instructions say to do).


I notice that there are 3 or 4 tuning "slugs" (or var caps - not sure which - some are enclosed in housings) inside the radio. These are accessible from the outside through well place holes in the bottom of the radio case. There is a small chart pasted on the bottom of the case saying that one row tunes the RF, one tunes the OSC and one tunes the ANT. They are even labelled as to which band each dial is for. This could be pretty handy!

In the manaul for this radio it says that one should have the BFO frequency dial and the antenna trim dial (on front of radio) both set at 12O'clock. The manual also says that these settings should give the maximum signal strength and "noise" volume. (I am sure it didn't call it noise though). What I find - on ALL four bands - is that the antenna trim gives optimum noise/signal volume around the 4 O'clock position - and slight variations DO make a big difference in the signal tuning - so it IS working. Similarly the BFO frequency dial seems to give optimum results around the 8 O'clock position.

I am wondering if these positions being so far from 12 O'clock is related to the frequency dial being so far off from the true frequency.

In other words, if I was to turn those "tuning" slugs or caps on the bottom of the radio - the ones that are for the "ANT" - would that effect the freq dial error and these other two knob position offsets? Obviously I can just experiment and try things, but I would prefer to have someone who is more knowledgeable about radio operation to give me suggestions or insights. I would hate to "tune" one of these and then find that I cannot get anything at all on the radio and can't find the position the slug had been in before I "tuned' it.


I don't think the manual mentioned these tuning slugs on the radio bottom - but I had better go back and see. Maybe there is some information there that I ignored because it was too technical for my needs when I was looking around in there.

AHA! The manual DOES have a very detailed procedure for getting the radio into proper adjustment! These procedures require a voltmeter, which I could easily get and already know how to use. But they also require a Calibrated Radio Frequency generator - which I suspect might cost a bit of money. We used to have "sine wave generators" in the physics lab where I worked, but I don't think those were "radio" frequency signals.

I will go out on the web and see what kind of prices I see on a generator of the sort required.

The manual gives very nice descriptions of nearly everything about the radio, both in layman's language and then also some fairly technical details about which tubes various circuits (BFO, Freq Mult etc) are connected in various radio settings. This is a pretty nice manual!

At this point, I am still more concerned with getting a better antenna set-up than I am with getting the tuning frequency lined up right. GETTING signals to listen to is more important to me right now than knowing the precise frequency they are really broadcasting at. The frequency thing will probably become of more interest later - if I can get better reception.

I have found several websites giving reviews of quite a few radios, including older models.
For example:
MY LAFAYETTE:
http://www.eham.net/reviews/detail/3182
This site says that
"The KT320 was the kit version of the HE30"

At this site I notice that the "average rating" given
to this radio is a scant 2.8 out of 5!
Description: Single conversation receiver with 455 kHz IF, dating from the early/mid 1960's.

One of the reviewers mentions the frequency readout problem, saying:
"Without a 100 kHz crystal calibrator the ability to estimate receive frequency any closer than a couple of hundred kHz was difficult at any frequency higher than a few MHz.
Although the HE30 did have a BFO its lack of a product detector made SSB reception a hit-or-miss proposition."
-----
I don't know what a "product detector" is.

------
Another "review" site for many radios:
http://www.eham.net/reviews/

-------
Oh! Here is something else I wanted to mention! I have been poking around at eBAY every day and then looking up reviews on the web, of the various radios I am finding. I see that a Lafayette radio manufactured a few years before mine is selling for a "buy it now" price off $180 plus another $20 or so shipping cost. And other old radios that are more on par with the one I have been calling my "cheapie" - are selling for about $120 plus shipping at eBAY. These all seem to me, to be very high prices for these radios! I bet that the existence and success of eBAY has really created more demand and raised prices on older radios like these. If you have been on the radio scene for a number of years, you can probably testify to that yourself.

As for "listening" - I have not done much of that. I did go on the regular "AM" band - which I do not usually do - and found a Reno Nevada station near 800KHz. And this morning I was picking up an English speaking station near 11MHz that was rolling in loud and then rolling out to almost nothing. I did not hear them say where they were broadcasting from, but it wasn't just an "image" or "splatter" from local AM stations because I get plenty of those and they "tune" much differently - being either spread over a very wide freq range, or else extremely noisy and peaked very sharply - but with no "rolling in and out" as genuine signals do.

That's my "report" for now!

Thanks again for hanging in here with me and giving your advice and feedback!

 

[Moleculo]

"Without a 100 kHz crystal calibrator the ability to estimate receive frequency any closer than a couple of hundred kHz was difficult at any frequency higher than a few MHz.

Well, that explains why 10Mhz seemed like 11Mhz on your rig. You can find some inexpensive signal generators on ebay: BK 2050 RF Signal Generator - eBay (item 170307567336 end time Mar-08-09 20:51:09 PDT)

It sounds like you can get a fair price for your radio on ebay. A lot of times collectors like old radios like that. Before you sink money into a signal generator, you might consider whether you're better off selling it, saving the signal generator money, and buying a litte newer SW radio. Another thing to consider would be selling it all and purchasing an older HF Ham radio that also has general receive (most do). You could probably find a decent older Yaesu or Kenwood for a pretty reasonable price, get your ham license and then both listen AND talk

Something to think about?

 

[Moleculo]

Yes, it would probably be a good idea to start a new thread in the Ham section. I'll split up this thread and start it off.