Kaar 10-Z Transmitter

[W9RAN]

I thought you guys might like to take a look at this unique transmitter - as far as I've discovered there aren't (m)any others on the air.  It took a request for help from Joe Cro N3IBX who has one that has been molested to get me motivated to figure this one out, since no documentation has been found.   I took a bunch of pics showing the wiring, etc to help with his restoration, and you can see them here:

http://smg.photobucket.com/albums/v652/ranickel/Kaar%2010-Z/

Fortunately mine was virtually untouched, with the exception of the dangling filter cap.  Unfortunately all the neat vintage caps were all bad and had to be replaced.  We haven't been able to find a schematic or anything on this transmitter other than what's in the Ray Moore's book.  It was introduced in 1938-9, uses a 6N7 oscillaltor driving an 807 final.  Audio is a carbon mic and 6N7 speech amp driving another 6N7 P-PP modulator - there is no mic gain control, just holler louder I guess.   As you can see there's a holder for a single 1.5 volt D cell for the carbon mic voltage.    I get about half brilliance on a 40 watt lamp dummy load when it's tuned for about 35 watts input so I'd say 20 watts output sounds about right.

There are two unique features: the transmitter has a built-in power supply to run from either 110VAC or 6 VDC using a vibrator (which actually works).  Also, the 807 feeds a built-in antenna tuner that's capable of matching a wide range of impedances.   There are three configurations:  "SER", "PAR" and "OUT" but none seem to like 50 ohms much, so I'm feeding it directly into the open-wire feeders for my 80 meter dipole.   But with doubling it's designed to cover 160-10 meters although the power obviously drops off as you go higher in frequency.

I got pretty good reports on it today using my 3885 crystal, but not so much when feeding an HA-5 VFO into the crystal socket to get on 3880.  Could have just been conditions at the time.

All in all it's a very compact and attractive-looking package;  as you may know Kaar became known for making early CBs as well as two-way land mobile FM gear before it was merged into Canadian Marconi in the 60s or 70s.   John Kaar was said to be a good businessman and engineer and I find no reason to disagree, but I've not found any advertisements or announcements in any ham magazines of that era.   That may explain why few 10-Zs were sold, and also makes me wonder if perhaps it was not intended for use by the Forest Service or some other gov't agency where portability, 6 volt power, and a built-in antenna tuner would be desirable.

I've included pics of my Kaar KE-23A receiver and Conelrad Monitor, which I use every day for BC listening.   Here's some additional info on Kaar products:  http://online.sfsu.edu/~hl/AN_FRR-26.html     Joe and I would be interested in any additional information about the 10-Z, especially the antenna tuner as I've pretty much traced out the rest of the schematic.

73, Bob W9RAN

[WQ9E]

Very neat looking rig Bob!  I am glad to see it is in good hands and will be on the air again.

[W1UJR]

Very nice Bob, I really have a soft spot for these vintage low power rigs, and yours seems to be a very uncommon example.

Photos are great, neat to get to see the insides of the set, they are very interesting indeed.

Bummer on the connector, looks like a Command set, but can't recall for sure.
The magic of super glue might work here.

Thanks for sharing that with us, and bringing one more part of ham radio history back on the air.

[W3DBB]

.

[W9RAN]

The Kaar 37 looks like a low power 'boat radio' with five crystal-controlled channels in the 2-3 mhz range and tunable BC receive.  The cabinet and speaker grille look to be the same as that used on the Conalert II - very cool!   I've converted one of the hybrid Heathkit boat radios to  3885.

Upon further review I now think the 10-Z was indeed intended as a ham transmitter, since commercial users like police dispatchers wouldn't have wanted all the transmitter adjustments to so accessible to the operator.  Also, the bandswitches are marked for the ham bands e.g. "10", "20-40", and "80-160" rather than in frequency ranges as on the HT-20, for example.   Since I haven't found any national ads, my guess is that John Kaar might have lined up a couple of distributors in big cities to carry the rig.   Portable operation was all the rage in the late 30s, but a low power portable transmitter that sold for over $100 in 1938/9 would have had pretty limited market appeal.

Thanks for the comments - I'd appreciate any tips or info on Kaar-related stuff.

73, Bob W9RAN

[Todd, KA1KAQ]

I think marine radio may have been the biggest part of their business at some point, Bob. There's a lot of old Kaar Radiotelephone rigs still out there, surfacing with some regularity.

Your transmitter and receiver are another matter. If I've seen 2 of each in the last 10 years, that would be a lot. My guess would be that cost could be a factor in why you don't see more of the amateur products. If the ads you posted are any indication, prices might've been more than what most hams would or could pay. I've yet to see a piece of gear made by Kaar that was cheap or lightweight.

We have one of the CONALERT II receivers here too, 'we' because my wife claimed it for her Cold War collection. Aside from that, my fascination has been with the IMP, Industrial Mobile Phone series. Most of them were used on forklifts (hence the antenna attachment on top), in work trucks or other business applications. These were set up on 154 mHz, though they did offer versions in the 25-50 mHz range also. I've got an original flyer for the early version IMP along with a couple of the VHF versions. Barely the size of a shoebox, but 20 lbs plus. Fortified with steel throughout. Thought about retuning one for 2m AM but decided not to, they'll be finding new homes soon.

The original TR-325 27mHz IMP is credited with being the first available Citizens Band rig in the new CB service. Over $300 for a single channel rig, no junk there. Impressive construction and quality components throughout.

[W9RAN]

Interesting you should mention the "Imp" Todd.  Kaar sold a $320 CB called the Imp and what looks like an identical radio called Imp that sold for $360 that could be set up for VHF low or high band, or for aircraft frequencies.  The CB and air band would of course be AM, but what about the business band radio? The ad doesn't say that it's FM, so I wonder if AM was allowed too back then?   If not they would have to make another radio that fit the same box, which isn't out of the question as I recall Kaar did make two-way FM gear for some time.   In todays mini-dollars, that was a $2.2K CB back in 1962!

Bob

[Todd, KA1KAQ]

Yeah, 2 way radios were anything but 'cheap' back then. No plastic, just metal. Kinda like the early VCRs vs. later versions.

IIRC, the original IMP was introduced in '57/'58 sometime. It was mainly targeted to Business Band customers and municipalities, but was indeed offered in 27 mHz form as well. Kaar was a lot like National, Hallicrafters and others in the way they just reused designs and parts across the fleet. In fact, the speaker grill used for the CONALERT receivers is also the one used for the IMPs. It started out with the same round KAAR emblem in the corner but later added a little wing with 'IMP' printed on it.

And yes - both versions of the IMP are indeed the same radio, both AM. All they did was change the required tuned circuits and crystals. I've got an original ad slick for the introduction of the TR-425 IMP tuned for 154.57 and it lists the modulation as "Amplitude plate, [A3]".

Only a couple watts output, but very cool looking little intercom rigs for local work. And did I mention - h-e-a-v-y?

[WB6NVH]

I too have a KE23 receiver similar to yours, Bob, except the cabinet for mine is not as fancy with the sheet metal work at the top, and mine is marked KE23X with a different looking logo on the nameplate.  The slide rule dials on mine are slightly different as well.  They seem to have made half a dozen variations of the KE23 model.  I understand there was one with a vibrator supply for DC operation but I don't know of anyone who has one.

[W9RAN]

I'd be interested in knowing if your KE-23 has electrical or mechanical bandspread tuning.  Kaar came up with a very clever arrangement by which the main tuning cap is mounted on what is essentially a hinge, so that it can be rotated through a small arc.  Turning the main tuning knob rotates the rotor as usual, but when you turn the bandspread knob, a mechanical linkage causes the main tuning cap to tilt slightly with it's rotor held stationary.  The result is bandspread tuning over a small range without the cost of a second multi-section variable.   There were several variants of the KE-23, and Ray Moore's book is in error as it says mine, which is marked at a KE-23A both on the nameplate and on the chassis, is supposed to have electrical bandspread yet it in fact has the mechanical type described above.    By the way, the schematic and service data (AT version) can be found in Riders Vol. 15.  The 6 volt option is basically the usual plug that disables the internal AC supply so an external one can be connected.   There's no mention of electrical bandspread but it has a squelch control, somewhat unique for a communications receiver.

[WB6NVH]

Mine has the same method of rocking the main tuning condenser for bandspread.  It looks essentially identical to yours other than a different nameplate and plain looking cabinet.   I had to restore mine using the Rider's data for the different receiver, because it was as close as I could find.

Mine has a pot for a tone control, whereas the Rider's schematic shows a rotary switch.

I was told that the bandspread scheme was somewhat popular on Philips and German communications receivers during WWII.  Seems to work fine.

I have finished the electrical rebuild of my receiver other than determining why the highest band is rather deaf.  After first powering it up, I almost immediately experienced a breakdown between primary and 500 Ohm secondary windings of the output transformer and had to cut that secondary loose to keep the set working.  Not surprising as the set was stored on a wet or damp surface and the paint is gone, replaced by rust, up to about 1/4 inch from the bottom.  It came with the factory matching speaker which is 4 Ohms, so I didn't need the 500 Ohm line anyway.

[Opcom]

here is something similar, a bit older and mobile.
http://radioheaven.homestead.com/KAAR.html

There have been one or two 10Z's gone through the local antique radio auctions here, a few years back. I looked but couldn't find pics. At the time I though they were VHF sets.  A lot of the older stuff either AM or FM, as shown in the .edu link in the fist post, has the traditional "K" speaker grille.

[WA1LGQ]

Here is a Kaar 37 that I found. It seems to be 5 crystal control channels in the marine band, with broadcast AM rx. Single 807 modulated by another 807 with probably carbon mic audio. I have the mic and cabinet with it. The battery terminal on the back indicates 12V, but it has a Kaar branded vibrator that says 6V on it. Can't find any documentation so far.
Larry