Blast from the past – Our Kenwood Hybrid Collection
Kenwood Hybrid Radios
For the past month of so a series of Kenwood Hybrid radios have shown up here. Most of them are from e-bay. I have had good luck with e-bay so far. But before you purchase on e-bay do your due diligence. Some sellers on e-bay have no clue abut amateur radio equipment, what the really have, if it works or not, or how to test it. To some sellers, if it “lights up” when they plug it in – it works. We know that a “working radio” is much more than this.
Hybrids in general – variations on a theme
The Kenwood models made from the mid to late 1970s to the early 1980s and designated TS-520, TS-530, TS-820, and TS-830 were know as Hybrids They were Hybrids because they were a combination of semiconductors and tubes.
The Hybrids were mostly semiconductor with only the driver and final unit being tubes. All hybrids used the same basic tube lineup – a 12BY7 for the driver and two 6146s for the finals. Output of these radios was about 100 watts. The 6146 tubes were very popular in ham radios. All the Kenwood hybrids used them as did the Heathkit SB-101, SB-102, HW-100 and HW101. You can find a very extensive article on the very popular 6146s in the resource section at the end of this article.
The 6146 valve was used in many popular Ham radios and they are still plentiful and cheap. A set (two) of 6146Ws, the military version of the 6146, which can be used in all models of Kenwood Hybrids can still be obtained for about $30.
Like driving a stick shift car, Hybrids having tube finals requires tune-up before you transmit. It’s not just set the VFO and go. Tune-up is really adjusting inductance and capacitance to resonate a tank circuit (inductors and capacitors) that provides the right impedance match simultaneously on a plate circuit and the antenna 50 ohm load.
All the Hybrids have the same cookbook approach to tune-up. All Kenwood Hybrids have the same set of 3 knobs labeled Load, Plate, and Drive that are used to resonate the tank and load circuits for the particular frequency on which you want to transmit. Change the freq and you need to touch up the tuning. No quick QSYs on these radios. Once you understand the operational tune-up process and execute it a few times you can get tune-up in about 10 seconds.
You will also note a Heater switch on all these radios. Again, the valves are only used to develop the final output on transmit. The valves are not needed for receive. There is no sense in lightning them up is all you want to do is tune around and listen. Kenwood gives you the option of not running the tube filaments even if the radio is powered up. The older radios that used tube finals did not have this feature. The final tubes were glowing all the time.
Another distinguishing feature of these radios is that they used functional component boards that were connected together with wire-wrap. That is, they represented a departure from point-to-point wiring. Take a look at the inside of an older Drake Ham radio like a TR-3 or TR-4. Looks nice and neat from the top. Especially those with the gleaming copper plated chassis on the TR-3 – real classy.
But then look underneath that TR 3/4 chassis and you will find a rat’s nest of wiring. Kenwood Hybrids don’t have that. They are built out of functional component boards that can be diagnosed and swapped as a unit. For example, in the TS-520S you will find a carrier board, generator board, IF board, NB board, AF board, VFO board, and so on. All nice and neat and connected together with edge connectors, wire-wrap, and wiring harness. Pretty neat and a major deviation from point-to-point wiring radios seen in the 1960s and earlier radios.
Hybrids – direct and to the point…
These radios are simple, direct, to the point, and not pretentious in any way. There are no menus, no memories, no CPUs, no DSPs, and there is nothing the radio does, that you need in the course of operating, that you can’t control from the front panel.
If you have messed with a ICOM 706IIG or similar tiny radio you know how frustrating it can be to do simple things which require you to access the elaborate memory system and the multi-function buttons. All dials and knobs on the Kenwood Hybrids have one function, clearly labeled, and at your fingertips. It’s not the modern radios are not fine pieces of ham radio gear – it’s just that sometimes simpler is better, less is more, and you just need to take a rest and enjoy yesterdays technology. This is why we have collected a few Kenwood Hybrids here at Southern Command.
TS-520S – First of the Kenwood Hybrids
The TS-520 was the first of the Kenwood Hybrids. It’s a very basic radio. It covers the Ham Radio bands minus WARC. It has VOX, a noise blanker, ACG fast/slow, RIT, RF gain, and Mic gain & compression. It has no digital display. You need some 2nd grade math to figure out the VFO frequency. Its simple. Add the number on the band switch to the numbers on the dial and that about where you are. The neat thing about the 520 is that the VFO has three sections that spin at three different rates of speed. Just add the value on the band switch plus two sets of numbers on the VFO dial and there you go – digital displays are for sissies.
I bought the TS-520S sight unseen from Universal Radio for $265 not including shipping. Universal told me that a technician had checked the radio, it was up to spec, fully functional, all knobs, switches, lamps were working. Universal also provided a 60-day return policy. The radio when arrived was in mint cosmetic condition. Great audio on receive and 100 watts out on 20m; slightly down on the higher bands. Very good purchase. I paid market price based on what these radios are going for on eBay.
TS-820S – My favorite
The TS-820S is a couple of increments of functionally and improvements over the TS-520S. This is my favorite radio of the Hybrids by far. The TS-820S has all the basic features of the TS-520S and adds: IF Shift; an FSK mode (in addition to CW/LSB/USB); and a Monitor function so you can listen to your transmitted audio. The big addition in the TS-820S is a digital display. You could actually read the full frequency off the radio without second grade math.
The big improvement – the digital display – is also the most common problem with the TS-820S. The digital display is really a separate frequency counter that is integrated into the case. It connects to the VFO and counts the frequency. The common problem is the “9s problem”. Every now and then, without warning, the display shows a number 9 in one of the positions. It comes and goes. There are various remedies posted to news groups on this problem. There is no quick fix. But the good news is that the counter and the VFO are separate and so the fact the frequency counter cant count does not affect the VFO or any other part of the radio. You can see the problem above.
The fact that the counter cant count the VFO frequency gives you all the more reason to play with analog dial. The analog dial is one up on the TS-520S now having 4 dials rotating at different rates of speeds. You have to take the VFO knob apart and fail to properly reassemble it to really appreciate how this works.
Take a close look at the picture below. Note the dial indicators of 460 and 450. That is really two dials intersecting – one dial that shows a “4″ and another that shows “60″ and “50″ respectively. (The number 4 is showing through a window in the outer dial.) As you spin the VFO knob one dial progresses a small increment to a 2, 3, 4 and so on as the VFO dial is rotated at a higher rate. In all, 4 wheels are spinning at different rates of speed to produce the VFO number to be added to the band switch setting. In the pictures above the band switch is set to 3.5 MHz. The analog dial reads 455. So the freq is 3.5 + 455 = 3.955 which is what the digital display reads – unless you happen to have the “9″s problem at the moment. The saga of why the VFO had to be disassembled is below.
I bought the TS-820S off of a seller on eBay. The seller was a ham of many years, heavy contributor to the Kenwood Hybrid newsgroups, and an electrical engineer by profession. After some e-mail exchanges about the radio and an exchange on the “straight dope” on the condition of the radio, we put in a low-ball bid. I lost the auction. But, got a eBay “second chance” from the seller as the high bidder was not a licensed ham and the seller refused to complete the sale with a non-ham bidder. I got the radio plus a MC-50 Desk Mic for $341. MC-50s are going for about $40-$60. So the price of the radio was about $300. The seller included the “9s problem” at no extra cost and fully informed us of this.
TS-830S – The Best and end of an era…
The TS-830S was the last and the most sophisticated of Kenwood Hybrids. To the TS-820S features, the TS-830s adds: audio compression level indication to the meter system; XIT Transmit Incremental Tuning; WARC bands; audio Tone control; Notch filter; and VBT (Variable Bandwidth Tuning). The IF shift and VBT in combination allows one to not only shift the pass band but also squeeze it at the same time. For digging signals out of a crowded band IF Shift + VBT is a great feature. The TS-830S solved the “9s” problem and the digital frequency readouts on these radios function without endemic problems.
I bought the TS-830S off of a seller on eBay. The seller was really a storefront for someone who had their hands on a lot of military radio equipment and test equipment. This person also had some unusual (and expensive) equipment from Cubic Corporation which, when I did some research on the equipment, found the use “classified”. After some e-mail exchanges with the seller and the “straight dope” on the TS-830S I purchased the radio “buy it now”. I paid more than market price for the radio based on its condition, the technical knowledge of the seller, and the fact the that seller had the test equipment and the knowledge to fully check out the radio. Market price for a TS-830S is $400-$550. The radio arrived as described in absolute mint condition. The seller included the original manual and Kenwood box. The manufacture date of the radio was 1981. So, in 2006 the radio is 25 yers old.
Buying Ham Radios (and esp. Hybrids) on eBay
Here are a few purchasing hints if you choose to buy one of these radios.
- Plentiful and a ready market. If you check eBay, you will find that the Hybrids are plentiful. This indicates a few things. a) The Hybrids have physically stood the test of time after almost 30 years. b) The radio is still popular and in use after 30 years. c) Best of all, there is an active market for these radios which means that when you are finished playing with the radio you can put it back up for sale and have a ready marketplace and ready buyers.
- All sellers are not equal. When you are looking for a radio like the Kenwood Hybrids you will find that there are folks selling these radios that have no clue as to what they are, how to use them, or how to test them. Some folks are regular people selling these Hybrids as if they are at a flea market and there is no difference between a ham radio and a lamp. Some folks are CBers that bought these radio’s thinking they could use them “as is” on 11 meters. That is not going to happen. Some sellers are CBers that tried to modify the radio for 11m, failed, and messed it up. Buy from any of these folks at your doom.
- Proper packing is essential. Kenwood hybrids weigh about 40 pounds. That is a lot a weight that you are placing in a box. Make sure the seller knows how to pack a radio that weights 40 pounds – double boxed, lots of crush space, peanuts, and bubble wrap. All of the radios I received were packed in a professional manner – but the shipper had plans for our radios.
Mentioned above was the fact that I had to disassemble the VFO knob and dials on the TS-820S. The fact is, the radio took at hit in shipping and pushed the VFO knob into the dials upsetting the delicate spacing. Disassembly of three levels of dials and adjusting the positioning of each was necessary to get the VFO to spin freely without binding.
Did the shipper (FedEx) treat the TS-830S any better? No. This seller had the most elaborate packing of the three Hybrids purchased. The box arrived with a large puncture hole on the side. Upon inspection, the puncture hole went through the outside box, 6 inches of void filled with peanuts, the inner Kenwood box, and through one layer of 4 layers of bubble wrap. The radio was undamaged.
The conclusion is simple. Radio history is valuable. You can buy a piece of radio history for only a few hundred dollars. Best of all this piece of history can be fully functional and used every day. It’s not history that sits on your self; it”s not history to look at; its history to use. A Kenwood Hybrid is close to a modern radio and they are plentiful. For the price of a contemporary radio such as a Kenwood TS-2000 or an ICOM 7000 ($1500) you can buy 5 older radios. Or, put differently, a Hybrid is 1/5 the price. Any way you slice it, Kenwood Hybrids are a great deal for the price and a piece of ham radio history. And when you want to sell them off – if ever – you have a ready market on eBay of willing buyers.
http://www.k4eaa.com/ (Vintage Kenwood repair, schematics, parts, and an overall great site for Kenwood Hybrid information)
Click on any of the thumbnails below to see hi-resolution images of these radios.
The family of 6146 Tubes