OBSERVATIONS FROM SCOTLAND

OBSERVATIONS FROM SCOTLAND 20 October 2009 GM1SXX

YABHR

YABHR you ask? Yet Another Big Heavy Radio... or words to that effect. On Sunday I headed to the Galashiels Amateur Radio rally along with Fred 2M0BIN from our radio club. The intention was to have a browse around, chew the fat and perhaps buy a few components. As luck would have it, a Trio TS-820S presented itself at a price I couldn't ignore, so I ended up taking it home with me. I also purchased a dozen 250uF@450V DC electrolytics because I can use them in my old radios, or perhaps in a DIY valve linear amplifier. While I was there, I met quite a few people I know including Azeem GM8KWQ and others from my local area. I also talked myself into joining RAOTA while I was there, so I had a grand day out. On the way to the rally, we took the scenic route, along the river Tweed, perhaps not the fastest route, but certainly a more interesting journey than the one I had found and printed out from the AA website. We saw a lot of migrating birds plus the usual pheasants... stupid birds with no 'road-sense'. Colourful, but stupid. The weather was in our favour, giving us a pleasant day, certainly a far better day than was going on in the West of Scotland.

When Fred and I arrived back at my house, I was pleasantly surprised that my 'better half' didn't complain about 'yet another b***dy radio' as she usually does. This is the true origin of the term 'YABR' :-) Fred and I has a pleasant cuppa in front of the telly before he headed off home. I don't think Fred bought anything at all at the rally. Shame on him!

After I had my tea, I had a quick look at my 'new' radio purchase. Everything seemed OK and since I had already done the all-important 'sniff-test' before buying it, I connected it to a dummy load and applied power. Everything seemed in order, so after a two minute warm up, I selected TUNE, preset the tuning for 14Mhz and pressed the send button. A quick load and dip job, and I was seeing 70Watts out on the CW setting, a bit low for this radio.

Off with the cabinet halves and out with the 12BY7A driver valve, substituted for a good used (tested) one, and voila... full power. On keying the TX, there was no power droop after 5 or more seconds key-down, so I'm pretty confident the 6146B's in the PA are fit and healthy. HT was a measured 850V off-load.

Removing the dummy load and poking a foot of wire into the aerial socket produced some strong stations on RX. Very nice indeed. All the controls operate smoothly and it does 'exactly what it says on the tin'.

I'm really a bit disappointed with this TS-820S. Honestly I am. It's absolutely perfect. I bought it hoping to have a 'project' to see me over the next few weeks, but apart from changing out the driver jam-jar, nothing needs done to it.

It delivers a measured 130W on CW (into my dummy load) and doesn't 'fade' so the driver and PA are 100%. It really only needs a good wipe with a cloth. It makes makes me wonder why I hear so much complaining about the sheer cost of getting into HF amateur radio when it's possible to buy a top-notch HF rig for around £100. OK as a newbie, you'd NEED to take someone with you savvy in the ways of dealers, and valves, but there are plenty of very nice HF radios out there to be had. I've bought quite a few over the years and none have needed any real work done on them. If they pass the 'sniff test', and look tidy with screws that haven't need 'chewed' or other signs of abuse, they are usually in acceptable electrical condition.

The all-important 'sniff-test'.

This is the most basic 'test' you can do after a visual inspection. Hold your nose an inch from the top grille and take a deep breath... through your nose. It it stinks of cigarette smoke, walk away. Do the same if you can smell 'burnt' smells or the smell of burnt paxolin. Overheated paxolin reeks of phenols. If it stinks of cigarettes, phenol or smells burnt, walk away! Cigarette smoke is very bad for switch and relay contacts.

If it smells 'neutral' and the radio looks cared-for with the cabinet fixing screw heads being clean and 'unchewed' and they are all present and correct, you *probably* have a good radio. If you can, have the seller power it up and check the receiver on a short piece of wire. If you have access to a dummy load, do a quick test on TX.

Remember that most problems can be fixed. Always rotate the bandswitch to see that it rotates properly, clicking between bands, and try all the rotary controls, looking for rough spots or 'stickyness'.

Back to the 820S! Even with the old 'soft' 12BY7A driver in place, the 820S easily delivered 70-80W on CW. Still perfectly acceptable. Any radio that passes the 'sniff test' usually has good PA bottles. RX sensitivity is excellent on the 820. A foot of wire poked in the back and I got lots of stations this morning. Another thing about the 820S is that it has some dedicated RTTY circuitry. A RTTY rear jack and circuitry are included to reduce the drive on data modes to protect the PA bottles. Sensible IMHO.

You don't want red-hot anodes... really you don't!

I think it will make an excellent data-modes radio. It's built like a brick outhouse with heavy gauge sheet steel and a diecast front panel. Weighs the best part of 40 pounds.

I'll give it a clean with AF spray (foaming cleaner) and re-lube the spindle sleeves etc. I might even clean the band-switch contacts with deoxit, if I get a 'round tuit' but to be honest, it works very well 'as-is'. I don't think you can compare these radios with new stuff. The old ones are almost always far better radios in the areas where it really matters.... like performance. I've yet to try a DSP radio that doesn't offend my ears.

If you think about it, even buying a hybrid with a fried PA would still be a good deal if it cost £100. A new 12BY7A and a pair of 6146B's wouldn't cost more than £40. Still a very cheap way for a newcomer or any licensed person for that matter, to get on the air. The 820 has another trick.... when switched to TUNE, it reduces the PA Screen Grid voltage so that the PA's can't be damaged by running excessive power into an untuned tank. I think the designers were trying to think of everything. It has a lot of clever features.

For someone who has just obtained their Advanced license, this would make an excellent and attractive base station. They'd have to learn at least one new skill, 'dipping and loading' the PA. This is a ten minute job to learn and is a useful skill to have. These old radios have some other advantages over new ones, such as having narrowband front ends that are excellent at rejecting unwanted signals. If you are a newcomer to HF and would like to try a classic hybrid radio like this one, get expert help to find one. These radios are not difficult to use, they are just not 'plug and play'. If you have a little bit of patience to learn to to dip and load them properly, they will give many many years of excellent service. Always always take someone who is familiar with these radios along if you plan to buy one and do remember that radios like this use lethal voltages in the final amplifier and driver stages. Your radio club is a good place to start if you need advice on getting active with a valve or hybrid radio.

73 AL.

GM1SXX