Primer or Howto for Repair of Hybrid HF Transceiver

[vk1rj]

Hello there,

Can somebody point me towards a guide for the restoration and repair of older Kenwood hybrid rigs please? My special interest is the TS530, but the problems I am having are probably generic in rigs which are 30 years old. Thanks es 73

Riccardo

Located on the southern coast of NSW, where it is high summer at the moment and all sensible people are in the shade with a cool drink!:-D

[KG4CGC]

First of all, Welcome to the Island. Enjoy your stay. One of our Radio Gurus should be with you shortly and hopefully can point you in the right direction.
In the meantime, enjoy a tiki drink. Compliments of the Island Bar!

15603

[K7SGJ]

Hi Riccardo. I have had a TS-530 since they day they hit the streets. What issues do you have?

If you are just looking for info, parts, etc, K4EAA (Ken) has a great site for Kenwood Hybrids at K4EAA.com. Both service and user manuals are located on the web. Google is your friend. And I belong to a couple of Kenwood user groups on Yahoo. One is Kenwood TS-520_820_530_830. There are several more on there that deal with Kenwood as well as other Hybrid radios of that era. There is a whole plethora of knowledge contained on those user boards. If you have something specific to address Fred has a lot of experience restoring these radios and putting them back into service. I have fixed my fair share of these units, too. I have always preferred these hybrid radios over many of the newer rigs. But, I play with both. By far the hybrids are a whole lot easier to work on and have a successful restoration.

At any rate, welcome to the Island. Pull up a coconut and make yourself at home.

[N8YX]

What they said. I keep coming back to the tube hybrids for some reason. Absent from my collection at the moment are a TS-530 and TS-830 though I'm going to remedy that some day. Really liked my '830 when I owned one in the early 80s.

[vk1rj]

Hello there...

Thanks to those who have responded. My situation is this:-
the radio is a ts-530s clone (a Bando technic )and while receiving just before Xmas, it suddenly quit. It made a sizzle noise and the 2A (slo-blo) main fuse went. I am assured that the PA stage is fully compatible with a TS-530 so am looking at what I need to check BEFORE I replace the fuse. The radio is at least 25 years old ... I've only had it a short while and is in excellent physical condition. I first thought of cathode resistors ... so I propose a careful physical inspection and maybe some measurements (I have read that the resistors go 'high' after some time and this creates problems. Next, I thought I look at the condition of the 6146 valves. Maybe also check the screen grid resistors. What to you think of this approach??

riccardo
VK1RJ/2

Here, it's high summer and was only +20 (Celsius) over night. Today it's supposed to go to 30!! Cheers.

[N8YX]

Get the tubes (all three) completely out of their circuits then have a look at voltages and resistances.There are a few articles floating around the 'Net which deal with the ubiquitous 6146 PA and various causes of failure. Cathode resistors and the tubes themselves are two things I'd start with.

[vk1rj]

Thanks for everybody's replies. I shall remove the 3 valves and check the voltage readings after we get back from our wedding anniversary trip around New Zealand. I shall then post the results to this list. Perhaps somebody can tell me where the pin-out for 6146B rf amplifiers can be found ... the one which specifies voltages. Maybe the tech manual for the TS530 gives this. Not much time to do this before we decamp on Sunday. Want to take my time and get it right. Also need to try and locate a local with a valve-tester. They are not common nowadays! Thanks again for help. Talk again in mid-February.

riccardo
VK1RJ/2

[N8YX]

Though I haven't downloaded the 530-specific documentation, I think Ken (K4EAA) has schematics on his site which show all the voltages. Likewise, Gordon (N6WK) and Ron (WB4HFN).

For purposes of your repair work, any of the Kenwood hybrid PA circuits can be used as a reference. This includes the TS-520, 820, 530 and 830. There will be slight differences in the band-switching and metering circuits amongst the various rigs but the overall design itself was re-used across all of them.

Yaesu and Uniden(Tempo) used less plate voltage and more plate current in their hybrid PAs. I haven't recently gotten into a Heathkit tube PA which uses 6146s but I assume the circuits are close enough for troubleshooting guidelines. There's a good bit of info floating around on the 'Net about the Heath stuff - SB-100, 101, 102 and HX-1681 are a few I know of that employ a similar driver and PA arrangement.

[VE7DCW]

Fred...also to add to this,also consider the age of the rig,was a re-cap done on all the older filter capacitors in the PS? ....I have corrected similar problems in a couple or older Yaesu's and a Kenwood with recapping them! :-D

[N8YX]

Good point, Gerry. I recently did the HV and MV sections of my FL-101 and changed a number of electrolytics on the other PCBs as well, although Yaesu used high-quality capacitors throughout their rigs of the period. They don't often go bad.

Examining the various voltages with a scope will tell one much about what's up with the power supplies.

[vk1rj]

An amateur friend and I have been investigating the problem. We discovered that the power transformer seemed okay. Also the various diode bridges seemed to test out as they should. On the HV line there are two 47uF electrolytics in series, each with a .01 cap plus a 470k resistor in parallel. A few fuses later we checked the state of the electrolytics ... and the first is a bit of a dead-short on the ohmmeter. At the same time there are spark discharges and another fuse blows!!
I've ordered some new electros off the 'net and they will be fitted when they arrive. getting new electro was not an issue (450VW) but they are pcb type ... not the chassis-mount originals. We will probably just remove the old electros ... and mount the assembly on a 7-way tag strip screwed to the radio chassis. I am conscious of the need to maintain air-flow and NOT blocking up holes.

More details after our next session.

richard
VK1RJ

[N8YX]

If you're repairing a '530, have a look here (about halfway down the page):

http://www.k4eaa.com/parts.htm

Since the thread started I managed to acquire a TS-530SP, two TS-830S "Gold Label" units (one a project rig) and enough spare parts to make things...interesting. Look at our "Mods and Repairs" area of the site. I'm going to start a mod/upgrade thread for both rigs. There's common DNA between the two (PSU, RF, PLL and Counter Boards, final assemblies) and many of the mods destined for one will work for both.

[KA2PTE]

On the recapping idea, surprisingly I see in lots of older gear the Elna capacitors are used and they hold their values pretty well even after 35 yrs or so.

When I worked the 830S low voltage power supply section on the AF-AVR board I checked the caps and the only one I saw obviously shot because it leaked electrolyte was C9 so I replaced it.
Others I checked showed ok so I gave up checking them all. I see the 530 also has this cap C9. Looks like maybe part of the 1st buffer after the balanced modulator if I read it right.

[KG4CGC]

KA2PTE, Hello and welcome to The Island. As is custom, your introductory tiki drink.

https://i.imgur.com/29OFBHI.jpg

[KA2PTE]

Thanks for the welcome KG4CGC.