Images on my TransOceanic

[KC4KFC]

Greetings Y'all!

I was tuning around on my Zenith Transoceanic up around 15 Mhz (MC) a couple of weekends aga and heard a ton of strange CW pulses above 15.1.  Then up farther I heard ssb.  Sure enough I was picking up 20 meters and the CW contest weekend. But I still got WWV dead on 15.0 Mhz and quite strong. I guess these amateur signals are on the flip side of the IF. I haven't heard any images on other bands, I don't think.

Shouldn't the Zenith reject these images? Not sure how it does this and how to fix the problem.

I followed the alignment procedures again the other day. Tuned across 15 mhz.... WWV big and strong and then farther up....... Wow... a great sounding AM station. KL7OF loud and clear, calling CQ, sounding great on the push pull audio of the 1949 T.O. Still an image but, man, sounded great. Crystal clear, no distortion. Loud as any broadcaster or WWV. KL7OF was in WA state and I'm close to Nashville, TN and this was late afternoon.

So good in fact I turned on my Kenwood Twins to see if I could contact him. Would you believe the audio on the T.O. blew away the Kenwood R-599D audio even running through the 15" speaker I always use. I was astounded at the difference.

So I don't know if I want to really fix the image problem on the Zenith but I do want to understand what is the source of the images.

And KL7OF, Steve if you see this, you're signal was huge and beautiful audio!

Thanks,
Mark   KC4KFC

[WQ9E]

Mark,

With the IF at 455 Khz and only 1 stage of RF the TO will start to have noticeable image response as you go up in frequency since the image is only 910 khz away from the desired frequency.  Does the dial seem to track OK with the indicated frequency?  The reason I ask is that most commonly the high frequency (or conversion if you prefer) oscillator tracks above the dial frequency so at 15 Mhz. on the dial the oscillator would be at 15.455 and the image frequency would be at 15.910.  It appears in your case the oscillator is at 14.545 with the dial set at 15 Mhz. and the image response is at 14.090.  I am not near any of my TO's to check how which side the tracking is on but someone else will hopefully chime in or I will check later.

Basically, there isn't much to do about the image other than checking for proper alignment of the RF and mixer stages.  Higher priced communications receiver used dual RF stages (or sometimes and outboard preselector) and ultimately dual conversion with a high first IF frequency to conquer the image problem.  Some of the receiver manufacturers tried to sell the image as being a benefit in their low cost sets (a quite dubious benefit) as stated in the manual that if image interference is bad on the desired frequency then try tuning the desired signal in on the image because interference might be less.  I think that was a clear case of marketing taking liberties with the manual (and I can say this with clear conscience since in my real job I am a professor of marketing).

Even with images the TO ranks high on the coolness scale; I have several different models along with the Hallicrafters knockoff.  The TO shows up a lot in movies including Key Largo and as I recall Bogie was featured in some ads by Zenith.

73, Rodger WQ9E

[KL7OF]

Mark... Thanks for the signal report..I was operating on 14.286 with my homebrew PP 100th's X 813s .....350 watts ,full wave loop antenna....

[KC4KFC]

Thanks, Rodger,
I was hoping I didn't do anything wrong when I aligned it. It seems to track ok I guess. I just aligned WWV to 15 Mhz and pick up a few broadcasters on the 19 meter band. It is a cool TransOceanic. It has the Loctal tubes and the one with push pull audio. Broadcast band is full of stations.

Now I guess I want to improve the audio from the Kenwood R-599D. It only has the speaker output but I might investigate picking off the audio to send to a tube audio amp.

I saw a TransOceanic in the movie Sunset Boulevard. I may have scared my wife when I shouted "Hey look a TransOceanic!" She of course couldn't give a flip.......

Steve you sounded great.....

73
Mark

[Steve - WB3HUZ]

Great Classic Movie.

Have you done much listening in the 25 kHz bandwidth on the R599D? It can sounds awesome when the band is quiet. The 5 kHz filter is a little too narrow for my taste. Got rid of my twins back in the 90's. Nice set and the TX can sounds quite good on AM.

[WQ9E]

Mark,

My wife actually spotted the first TO I bought.  We were on our honeymoon in Maine and stopped at a restaurant/antique barn and as we were browsing the aisle Maureen called my attention to the TO.  Definitely a keeper (my wife that is!) and the H-500 TO isn't bad either.

Steve is right, the audio on the Kenwood R-599 does sound great when you can open it up using what is normally the FM filter.  I was a new general with a new SB-102 when I first used the Kenwood twins at Field day 1976.  They were set up at the 10 meter station and I was thinking the receiver must not be very sensitive when suddenly a signal popped out of the silent background; unlike my SB-102 the R-599D is really quiet on 10 meters.  I own an A and D line now and I always thought these were some of the nicest looking small radios with very nice performance and that great Kenwood gear reduction VFO drive.  If only the T-599 covered 160 meters like the receiver they would be the perfect small vintage station.  The AM filter in my Heathkit SB-301 actually started life as a Kenwood R-599A filter and I acquired this when I came across one being parted out.

Enjoy your TO!

Rodger WQ9E

[KC4KFC]

Usually the QRM keeps me from listening at 25k wide. I do like the 5kc wide most of the time.

I do like my Twins. Have had them almost 20 years. I think the D line was about 1978 vintage. Only thing I have done to them is to replace an RF choke on the transmitter. Oh, and maybe I have replaced the finals and driver.

They are a great looking design and smooth chain driven vfo but I am surprised at the audio. It beats the hell out of the Icom 706 feeding the same 15" speaker but not as nice sounding as my Hallicrafters SX-101 through a communications speaker.

It sounds as if the bottom end is rolled off severely and the mids and high mids emphasized. Unfortunately there is no record out or line level audio out. Anybody suggest where I should pick off audio? Is it best at the volume pot? Through some value cap? I have an old EICO monoblock amp that sounds pretty good, I would feed it to.


Mark