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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment. |
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28th Dec 2016, 11:32 pm | #1 |
Pentode
Join Date: Jan 2006
Location: Amsterdam, The Netherlands
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Racal RA17L Aerial range 1-2 Mhz
I am troubleshooting a racal for a friend. All works well except that its receiving nothing on 1-2 Mhz switch position.
What would you check first. All soldered contact spots on the switch (wafers) + Coil L8 and C233 ? kind regards Qwenix |
29th Dec 2016, 8:30 am | #2 |
Dekatron
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Re: Racal RA17L Aerial range 1-2 Mhz
I have found a few different faults in this circuit, but in the main, retensioning the switch contacts slightly has helped. I have also found broken wires where they attatch to the switch wafer.
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29th Dec 2016, 9:32 am | #3 |
Dekatron
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Re: Racal RA17L Aerial range 1-2 Mhz
There is a Yahoo group called RacalRA17forum that might be of help
Craig |
29th Dec 2016, 11:55 am | #4 |
Pentode
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Re: Racal RA17L Aerial range 1-2 Mhz
Sean and Craig thanks for your comment. I know the Racal group, I'm a
member ... ;-) |
5th Jan 2017, 12:33 am | #5 |
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Re: Racal RA17L Aerial range 1-2 Mhz
Check for a burnt out coil for that range. I've had that, although not on that range.
Al. |
17th Jan 2017, 12:56 pm | #6 |
Pentode
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Re: Racal RA17L Aerial range 1-2 Mhz
Depending on what the user said to me. He said in position 1-2 bit deaf...(on the end of the band between 1500 and 2000 kHz In the position 1-2 Mhz.) This is the band he uses the most.
I am not capable to realign filters so hands of and no adjustments made. less knowledge and no equipment to do this. Only wanted to improve as far as my knowledge goes... problem: No aerial tuning possible. Peaking is out of reach anticlcockwise. I first checked the valves. Result 1 mixer E180F warm shortcircuit, other mixer E180F lost vacuum.. white inside. The 6F33 bad emission. All tested on the TV7D/U good or bad... Changed all three and checked all the rest of the valves. All OK. Result aerial tuning back on track and good reception on all bands. Peaking with aerial tuning withing the adjusting rotation possible. In the receiver was no GZ34 fitted springretainer was still there and under the chassis a B250C1500 fitted.. Impression was that this receiver was heavily used... and hard smell of nicotine... Further actions internal coax had bad soldering. So cracking sound sometimes So resoldered that one. 1 Mhz crystal pins and socket cleaned. Strange enough the EK90 mixers inside are very sensitive for chassis vibrations. Changing them into other EK90 made no difference. No realignment done. Checked all bands and aerial tuning works. Receiver is back to the owner. |
17th Jan 2017, 10:55 pm | #7 |
Tetrode
Join Date: May 2012
Location: Oxfordshire, UK.
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Re: Racal RA17L Aerial range 1-2 Mhz
I have also had issues with the EK90/6BE6 mixers being sensitive to vibration also with them not seating properly in the valve holders, even after replacing both valves and the holders - almost as if the valve pins were undersize.
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18th Jan 2017, 11:12 am | #8 |
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Re: Racal RA17L Aerial range 1-2 Mhz
If you have valve holders that are of the type of construction whereby the individual sockets have pins that only make a contact with the edges of the valve pin - change them for the type of socket that uses a 'wrap around' type of contact. I've had more trouble with those edge-type sockets than I care to remember. They seem to be common in Eddystone radios.
A similar argument also applies to turned-pin i.c. sockets - for same reasons. Al. |
18th Jan 2017, 7:09 pm | #9 |
Pentode
Join Date: Jul 2009
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Re: Racal RA17L Aerial range 1-2 Mhz
First job I do on any deaf or dead Racal is to give all the valves a wee wiggle!
Often as not, it results in some signs of life. Colin. |
18th Jan 2017, 9:34 pm | #10 |
Dekatron
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Re: Racal RA17L Aerial range 1-2 Mhz
Cheap "McMurdo" B7G/B8A/B9A valveholders are always worth treating with suspicion - the brass used for the stamped-from-sheet contact-forks has a distinct tendency to crystallise and after a few decades you get a fracture at the base of the forks which means they no longer make proper contact with the valve pins.
Wiggling the valves can sometimes temporarily restore contact - but it's only a temporary affair. To be assured of future reliable contact you need to replace the valve-holders. I've got a drawer-full of "Cinch" valveholders here reserved for this. |
19th Jan 2017, 1:07 am | #11 |
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Re: Racal RA17L Aerial range 1-2 Mhz
Indeed: your experience and remedy matches mine.
Al. |
19th Jan 2017, 1:23 am | #12 |
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Re: Racal RA17L Aerial range 1-2 Mhz
There's a lot of valveholders in an RA17!
But I don't think the loss of one band in the preselector, but not its other bands could be a badly connected valve. There will be plenty of gone-high resistors and leaky capacitors to track down as well, to get the beastie running reliably, but there sees to be a hard fault in a coil set or a switch David
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19th Jan 2017, 11:49 am | #13 |
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Re: Racal RA17L Aerial range 1-2 Mhz
Indeed there are. I have had more than just a few RA-17 and Eddystone radios across my repair bench over the years, but the above described problem with the valve-holders has been rare on the RA-17 but quite common on the Eddystones. That might be due to the Racals having been used in a more benign environment than the Eddystones. Might be due to a higher degree of QC in the former, compared to the latter. Each were aimed at a different market, with a price differential that reflected that!
Al. |
20th Jan 2017, 1:42 am | #14 |
Pentode
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Re: Racal RA17L Aerial range 1-2 Mhz
The valve contact issue is often due to the set having been stored in a damp shed or shipping container between the last "official" user and the surplus market. The same could well cause corroded litz wire to solder joints. I've also seen SM caps inside coil cans going open circuit.
It's as well to have the VFO1 out anyway to replace the 100k resistors in the cascode amp; also the VFO output will almost always be cleaner and more stable after replacing the Rs and Cs in there. You can check out the switch and inside the relevant preselector can while you're in there - I'm sure one of us will be able to sort you out with a spare if need be. I usually only give the valve sockets a gentle clean if they aren't charred or broken. Being signed off work with a prolapsed disc, I guess I'm excused Racals for a bit! Cheers, Colin. |
20th Jan 2017, 9:47 am | #15 |
Hexode
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Re: Racal RA17L Aerial range 1-2 Mhz
There are still some broadcast sations on the 1-2 mc/s band. Do they come through on the "Wide Band" setting?
Don m5aky |