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Author Topic: Heathkit HR-10B Couple of Questions  (Read 17468 times)
KE4OH
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Posts: 233




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« on: March 31, 2015, 05:53:33 AM »

I just got a beat HR-10B and brought it back from the dead. Just a simple power supply recap, free and clean the frozen bandswitch, clean up a few sketchy grounds, etc. It's working pretty dang good already. Audio is good and 80m-20m are pretty sensitive. 15m an 10m, well, not so much, but that is to be expected.

I have a manual, so I'll follow the alignment instructions in there. But I don't see anything that covers one problem I'm having. On 80m and 15m, the dial tracking is pretty far off. So much so that the cal adjust won't bring it to where it should be.

1. On most receivers, there are padders/trimmers on each band to adjust for this. Not on this guy. I'm not real bright on stuff like this, but I'm thinking the best way to go will be to sub in a different value cap across tuning coils L11 (80m) and L14 (15m). Sound like a plan?

2. The other question I have: On 80m and 40m, advancing RF gain past a certain point is causing an oscillation such that the audio become very distorted. Any tips for this?

TNX ES 73, Steve
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73 de Steve KE4OH
W1BR
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« Reply #1 on: March 31, 2015, 06:27:11 AM »

I'd wonder if the original caps have shifted value?  But, usually those receivers align without much problem, and since they only cover the ham bands tracking isn't usually too much of a problem.  Note that there are two fixed caps across the oscillator coils. One is a special temperature compensating cap.

You could try replacing the fixed cap, but the original values should be pretty close.

Regarding the instability, that indicates that a bypass cap might be missing in the RF stage, or that the kit wiring is sloppy and causing an unwanted feedback path.

Sensitivity on the higher two was never great... as I recall Heathkit ran the local oscillator at 1/2 frequency to improve stability, but that reduces LO injection.

Pete
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AD4U
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« Reply #2 on: March 31, 2015, 06:42:18 AM »

I just finished bringing a HR-10B back from dead too. Mine has 0.1uV sensitivity on 80 and 40 and a bit less than 1.0uV on 20. 15 and 10 for all practical purposes are useless. Once warmed up mine is quite stable on 80 and 40 CW.

My goal is working DXCC with the HR-10B and the DX-60B on 80 and / or 40 CW. That will be a challenge.

Since this receiver does not use LO crystals, the frequency is determined by L and C. If you cannot bring the receiver into decent calibration on some bands by adjusting the coils (L) the corresponding capacitor C may have drifted out of tolerance.

Dick AD4U
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VE3LYX
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« Reply #3 on: April 05, 2015, 06:00:17 AM »

I just returned mine to service too. Both my Dx60B and my HR10B crapped out the same week. The HR10B was a small cap and the audio output tube. To be honest it is not my favourite receiver but I do use it a lot with my DX60B as it seems the proper thing to do. I think I have been using it now about 3 years. Dial calibration? Listen, the person who thought many years ago to use fishing line to run a capacitor should have been horsewhipped on the spot. I have three of them A HR10B A trio 59R and a DX160 RS. None of them are correct. Oh I lied , I also have a Heathkit Mohican so that is four. Still it is a very serviceable and user friendly rx  the HR10B so it is allowed to sit above its cousin the Dx60B. Mine is not much good for SSB but since I don't have any of that in the downstairs AM shack I have choosen not to worry about it.
don
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KE4OH
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« Reply #4 on: April 06, 2015, 06:11:33 AM »

Yeah, well, it's not a great RX, but mine does a credible job on 80m-20m. The dial calibration is close enough on 40m and 20m. But it's just too far out on 80m and 15m. I don't really care that much on 15m, as the thing is so deaf.

So, I didn't know if there was a "trick" to improve the dial tracking. Looks like I'll be subbing in a few caps. Shouldn't be hard, other than just getting at the the bandswitch with the soldering iron.
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73 de Steve KE4OH
WB4SPT
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Posts: 777




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« Reply #5 on: April 06, 2015, 12:47:08 PM »

The HR10 L.O.  is very simple Shocked
If the band has too much spread, you might consider adding a series cap on the way to the bandswitch, before the air tuned cap.  This way, you will tune less of the band.  
If the band has too little spread, well, you would have to repaint the dial Angry

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KE4OH
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Posts: 233




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« Reply #6 on: April 06, 2015, 01:12:42 PM »

Actually, the problem is that the lower band edge is off the scale. Such that I can't move it back on the printed scale with the dial cal control. I could live with that, but I'm also losing like 30 khz on 80m and more than that on 15m. I'm a CW OP, so I really want to regain that real estate. Looks like I'll be subbing in some different LO caps on the naughty bands.
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73 de Steve KE4OH
WB4SPT
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« Reply #7 on: April 06, 2015, 01:31:28 PM »

OK, if the supplied L's are out of range, then you will be forced to modify the C values.  You may still have a spread issue.  Luckily, each band appears to be independent of one another. 
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W1BR
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« Reply #8 on: April 06, 2015, 10:20:10 PM »

OK, if the supplied L's are out of range, then you will be forced to modify the C values.  You may still have a spread issue.  Luckily, each band appears to be independent of one another.  

Oh,  please... they are SLUG TUNED COILS.... retuning the slugs adjusts the inductance, and there is more than ample tuning range!!  This radio has a very narrow tuning range on any band. There is NO NEED to add series padder caps in seris with the coils.

Pete k1zjh
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KE4OH
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Posts: 233




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« Reply #9 on: April 07, 2015, 05:40:50 AM »

Well, Pete, the bulb just went on in my head! Thanks for flipping the switch. Yes, now I realize that properly adjusting the LO coils should walk the coverage back onto the printed dial. For whatever reason, I was thinking about the LO coils as if they were IF transformers, which they are not!
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73 de Steve KE4OH
G3RZP
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« Reply #10 on: April 07, 2015, 06:13:26 AM »

Are there trimmer capacitors as well? If so, adjust the coil slugs at the BOTTOM of the band and the trimmer caps at the TOP of the band. Usually about 5 to 10% in from the dial end frequencies are best.
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W1BR
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« Reply #11 on: April 07, 2015, 06:23:55 AM »

Hi Peter

No trimmers, no padders.  The inductors for the front end are slug tuned. The coils have fixed value caps across them.
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G3RZP
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« Reply #12 on: April 07, 2015, 08:49:58 AM »

So the dial calibration depends on the fixed capacitors being of tight enough tolerance and staying that way.....and the variable capacitor being tight enough on tolerance.

I'd fit trimmers if the dial couldn't be got right.

I go bitten once by variable capacitors being slightly different in tuning law from batch to batch, although I could never see why or measure any physical difference......Bending the adjustable segments in the end vanes works if you are only dealing with one band, or matching sections of a tuning gang accurately.
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W1BR
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« Reply #13 on: April 09, 2015, 06:48:21 PM »

Peter

Most of the LO coils have two fixed caps across them: a NPO and a cap with a negative 750 coefficient. I suppose one could reduce the value of the NPO by say 25pF, and add a 50 pF trimmer across the coil to permit closer tracking between the low and high ends of each band..

I had a HR-10 paired with a DX-60 during my novice days back in the sixties. The internal calibrator was good enough to permit keeping the radio honest as to frequency.  It wasn't a great receiver, the half lattice crystal filter wasn't adequate for CW work. But, it was light years ahead of the KT-200 Lafayette receiver that preceded it. Most hams hated the HR-10, but in reality there wasn't much in it's price class that could beat it.

Pete
« Last Edit: April 10, 2015, 08:03:43 AM by K1ZJH » Logged
KE4OH
Member

Posts: 233




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« Reply #14 on: April 10, 2015, 06:28:20 AM »

No, the HR-10B isn't a great receiver. But, I'm a dyed in the wool boatanchor OP. So when I found this one for short money, I had to have it.

Iv'e listened to mine long enough on 40m to know that it will be just fine for me. While the filter is broad as a barn on CW (the only mode I really work), CW bands aren't that crowded. I can live with it. Between the adjustable BFO and judicious use of RF gain, plus years of using cranky old gear, I can usually pull in a readable signal as long as they aren't too far down in the noise.

Agree about the calibrator. Mine has it, and it's by far the best part of the rig! Once I do an alignment and walk my couple of naughty bands back onto the dial scale, I should be good to go.
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73 de Steve KE4OH
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