The AM Forum

In a 1941 Hallicrafters ad for the HT-4 transmitter, it says tuning units and coils are available for 160m through 10m. Please see attachment.
I have never seen any for 10m or 15m. Has anyone else ever seen them? If not, were they really ever produced?
If they did make them, I sure would like to find a set to use in my BC-610.

Thanks,
Dan

That's a conundrum.   See, the marketing literature all says up to ten meters.

But, the owners manual...... It only states to 18 mc, shows the plug-in coils to 18mc and then goes on to list both the coils sets and  tuning units....

And they only go to 18 mc.

Seems marketing and engineering might not have agreed.

--Shane
WP2ASS / ex KD6VXI


Edit. Added the HT4 manual, thought I did yesterday.   But the official manual shows operation only to 18 mhz on the HT4.

Hi Dan..seems a bit odd they wud have included 15mtrs..that wasn't approved until the early 50s I believe..anyhoo wonder if one cud "roll" their own..?..gud luk 73 de DAVE WB1EAD

Hi Dave,

Well, that was my mistake.  The ad said 10 to 160m and I didn't realize 15m wasn't a ham band until the 50s. :)

Thanks,
Dan

HT-4 owners manual, page 8.  No mention of ten meters in the owners manual.

See attached screenshot.

Seems marketing probably got ahead of engineering.

--Shane
WP2ASS / ex KD6VXI

Shane,

I noticed in the manual for the HT-4 that you posted, is for the later version HT-4 that was styled like the BC-610 at the end of the war or post war. The manual even has military TM numbers on several of the schematics and other drawings in it. This all makes me wonder if the pre-war HT-4 manual said the same thing as yours about band coverage?

I have looked for a pre-war HT-4 manual, but have not been able to find one anywhere online.

Thanks,
Dan
 

I am just wondering, if by chance, 10m operation on these transmitters was accomplished by frequency doubling in the final stage? If so, 20 meter drive at 14 Mhz, and a 10m output coil would work. The efficiency might be crappy though.

Jim
Wd5JKO

Jim,

I am very interested to find out why Hallicrafters apparently dropped 10m operation. Was it poor efficiency on 10m, lack of communication between engineering and marketing or was there actually a problem?
 From what I've read, the HT-4 was initially introduced in 1938 and the ad I posted was from a Hallicrafters 1941 catalog, which actually said 1941 on page 2. You would think marketing and engineering would have aligned before 3 years had come and gone. Out of curiosity, I would sure like to understand what was going on.

Dan

I'm digging back 50 years, but I recall, at a TV station I worked for in transmitter operations, that we had an HT-4, crystal controlled on a 26 or 27 mc frequency.  We used it to send a tone to another hilltop to our south to switch the network feed from microwave to an off-air receiver so we could take programming from our sister station to the south when the 2 gc microwave was acting up.
But it essentially operated on or near the 10 meter band.  It was entirely reliable so I never had to repair it or get to know it well.  Any of my old acquaintances who would know anything more definite have all gone beyond the ionosphere,
73 de Norm W1ITT

Norm,

Well, that shows Hallicrafters probably did actually sell a 10m coil and tuning unit as shown in their early advertising. I wonder why they didn't offer it after the war?

Thank you,
Dan