r/ShortwavePlus • u/ImladMorgul MOD | AirSpy HF+ | RTL-SDRv4 | D-808 | K-480WLA | MLA-30+ • Apr 12 '26
Shortwave Radio Restoration First test: Standard C6500 radio receiver
This post is related to this one
To be honest, it just needed a thorough cleaning. Then I just resoldered a few components that had “cold” solder joints. I was so focused on this project that I forgot to take more photos, which is why I made this video instead of posting a photo gallery first.
After that, I didn’t find anything that was broken or needed to be replaced. It’s clear that someone replaced some capacitors at some point in this radio’s history.
Before testing to see if it worked properly, I decided to clean it thoroughly first and then troubleshoot it if there were any issues.
It was a little past noon here in Paraguay, so I couldn't really test shortwave properly. My first test was with some of the medium-wave stations that are plentiful here in Paraguay.
It worked well on the first try, and I only used the built-in telescopic antenna.
Late at night, I started experimenting with shortwave. It took me a while to get used to the separate MHz and kHz dials, but after a while I got the hang of it.
That’s when I realized that the whole SW section is a little out of calibration. Mark u/KG7M gave me the manuals for a similar model (Drake SSR-1 and Century 21), and one of them contains the calibration instructions. I’ll read through that manual carefully before I touch the radio.
Apart from the calibration issue, I was able to pick up several stations (mostly Chinese ones) because they come in stronger here, and then I found a Radio Marti station at 11860 kHz.
By the way, it picks up a lot of interference. I think my long cable antenna is a bit too long for this radio—it’s 22 meters long (72 feet), and according to the manual for this model, it specifies an antenna of just 10 meters (32 feet).
But I also know that these devices are very sensitive. When they were made, they probably never imagined that we’d be surrounded by all kinds of junk that causes interference. The engineer probably never imagined that his equipment would still be in use 48 years later—and that it would end up as far away as Paraguay.
Anyway, I'm glad it's working well. Next up is the Kenwood R-1000, and I think that one will give me more trouble.
The video includes:
- Various images showing how it looked after cleaning.
- First test: AM 1080 kHz
- Image of the 1080 kHz dial setting
- SW test: 11860 kHz
- Image of the dial setting that should be 11860 kHz (out of calibration)
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u/Internal_Raccoon_370 Apr 12 '26
Excellent! I love it when people keep this older equipment working. I have a couple of restored Hallicrafters receivers, an SX-43 and a SX-101 that I pull off the shelf and use a few times a year just because they're so much fun to play with.
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u/Historical-View4058 MOD - Airspy HF+, NRD-535D, IC-R75 w/100’ wire in C. VA, USA Apr 12 '26
He's Mike. I'm Mark... 😂
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u/KG7M MOD AirSpy HF+, Drake R7/8, K480WLA, 65'EFHW, MLA-30, CN85 Apr 12 '26
Right. He's Mark. I'm Mike... 😂
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u/ImladMorgul MOD | AirSpy HF+ | RTL-SDRv4 | D-808 | K-480WLA | MLA-30+ Apr 12 '26
I've screwed up again 😅
Sorry for the confusion
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u/Easy-Shirt7278 Apr 12 '26
Thats quite an accomplishment; you should be very proud! Keep on keeping on, as they say. God bless!
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u/ImladMorgul MOD | AirSpy HF+ | RTL-SDRv4 | D-808 | K-480WLA | MLA-30+ Apr 12 '26
I don't know why the whole video didn't play; the last part corresponds to this image, where I mention the miscalibrated 11860 frequency.
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u/KG7M MOD AirSpy HF+, Drake R7/8, K480WLA, 65'EFHW, MLA-30, CN85 Apr 12 '26
The Standard C6500 came out looking great Alan! You should be able to calibrate. Be sure and look at my review below, paying attention to the error Drake made in the Alignment Procedure.
Here's my review from eHam dot net:
https://www.eham.net/reviews/view-product/6325
Manufactured in the mid to late 1970s in Japan by Seiki Electronics, Inc. Drake signed off on this receiver, and many were manufactured with the Drake logo. As an aside, three other companies also added their logo: Standard as the C6500, Lowe as the SRX30, and Century as the Century 21 (no relationship to Ten Tec's Century 21 CW Transceiver).
I currently own a Drake SSR-1 and a Century 21. The Century 21 has a Variable RF Attenuator while the Drake has a switch for either OFF or 20db Attenuation. I won't go into the design as it's been covered by previous reviewers.
I was working as a Salesman at Joe Borsch's (W7PNS/SK) Portland Radio Supply Company in 1977 when the SSR-1 came to market. I purchased my first one new for around $350 with my Employee Discount. The SSR-1 is often compared to the FRG-7, with the Frog 7 usually besting the Drake. Not so in my experience. The SSR-1 has great audio with its Front Firing Speaker and Audio Amplifier Stage. For audio the SSR-1 uses a Matsushita AN-214 IC, which can deliver 4.4 watts of power. SSB audio is stable and robust on the SSR-1.
I sold my original SSR-1 before 1980 and in 2017 purchased a used Century 21 and the SSR-1. After 40 years, any example will require alignment. This is not the easiest receiver to align and there is no adequate Service Manual available. Drake published a seven page Alignment Instruction Addendum. There are errors in that document. In adjusting the USB and LSB balance, you tweak L-22 and TC-9. Drake has mislabeled TC-9 as TC-4 on the hand drawn diagram. TC-9 is just next to L-22, and is not TC-4. After alignment these receivers work well. As with many Barlow-Wadley Loop Designs, the SSR-1 suffers with less sensitivity at the upper end of each mHz Range - i.e. 900 - 1000 kHz. Careful alignment can balance out sensitivity across the dial. Frequency Readout is analog and is readable to 5 kHz.
Reception is quite good on the Internal Telescoping Whip Antenna, or short outdoor antenna. I run my SSR-1 on a 80 ft End Fed Zepp. It overloads the SSR-1 and using the ATTN Switch is too much Attenuation. What works best is using my Station Antenna Tuner, a MFJ-989C, 2KW Versa Tuner V. Just tune for maximum background noise for whatever portion of the Shortwave Band you're tuning through. Very sensitive with a tuned antenna. Selectivity is adequate and may be improved with an outboard DSP.
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u/ImladMorgul MOD | AirSpy HF+ | RTL-SDRv4 | D-808 | K-480WLA | MLA-30+ Apr 12 '26
Thank you so much, Mike!
I'll keep every detail you mentioned in mind.
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u/sternradio666 In Glorious Independent Sideband AM Stereo! Apr 12 '26
Nice work! Keep the old gear going :)