HR10/10B Sensitivity

[doug807]

Anybody ever have any success in getting the Heathkit HR-10/10B to work on 20, 15 and 10 Meters.  I've got a pair of them here and both work great on 80 and 40 but are quite deaf on the higher bands. These make very good sounding AM receivers and the 4KC bandwidth is quite usable even under crowded conditions.  Alignment does not seem to help the problem.  I'm starting to think that this is a design flaw and it is what it is.  Any suggestions?  73 Doug K2JJ

[VE1IDX]

I would be interested in hearing about that as well.I am soon going to dig out the DX-60B,HG-10 VFO,and HR-10 receiver from storage at my parents place and put it back on the air.As I remember it the HR-10 was quite deaf on the higher bands and not all that great on the lower ones as well,at least not when compared to my Kenwood R-1000.

[w3jn]

Well, my grandpa always said "you can't polish a turd"...

But that doesn't help you with trying to get a halfway usable HR-10.

Looks like a couple things may be going on here.  The tank circuits for 10-15-20 in the grid circuit of the mixer toob appear to have an inordinately high C/L ratio.  There is no way you're going to be able to do anything about that.  A poor design choice, as with most Heathkit receivers of this vintage.

The second issue may be decreased LO level at higher bands.  This is a prime cause of apparent loss of sensitivity in boatanchor receivers.  Many times, there is nothing at all wrong with the front end and mixers, but the LO level drops off dramatically at higher frequencies.  A quick reading with a 'scope will tell for sure.  Subbing carbon film resistors for the carbon comps that are in the oscillator and mixer circuits *may* help; also perhaps some of the bypass caps in the LO/mixer area are a bit iffy and/or have too long leads to be effective at higher frequencies.  All in all, it's probably a LOT of work for very little, if any, payoff, especially considering the other shortcomings of this radio - poor AVC, lots of distortion, etc.

These things are fine to play around with, display on the shelf, and bring yourself back to your novice days, IMHO life is too short to have to depend on one of these things for regular use.  See "Johnny Novice's Guide to Receivers" in the East Coast Sound section of amfone.net for some suggestions on some radidios that'll make your ears a lot happier.

73 and good luck - John

[Pete, WA2CWA]

Don't screw with the receiver. It's not worth the time or effort. Build a 10, 15, 20 meter converter and feed it to the receiver. QST, May 1960, is a place to start. Lots of them around in QST, CQ, HR, and 73 over the years.

[Paul, K2ORC]

Well, my grandpa always said "you can't polish a turd"...

Well, your grandpa had a way with words.  :lol: :lol:

Paul K2ORC
Brotherhood of Turd Polishers,  Local 3825

[WA1GFZ]

There is a MBA course on making a turd shine but you have to start with bull turd.

[w3jn]

Paul - izzat the INTERNATIONAL Brotherhood, or just NY state?

[W1RKW]

Ever try Turdle wax?

[WA1GFZ]

liquid or paste?

[ve6pg]

I USED TO HAVE ONE..A GUY PLEADED WITH ME TO TAKE IT...IT MADE A GREAT DOOR-STOP.

[Paul, K2ORC]

Paul - izzat the INTERNATIONAL Brotherhood, or just NY state?

International, of course.  Shanghai is the fastest growing local.

[doug807]

Thanks for the input guys.  Yes I know about polishing turds. I suppose we've all gotten our hands a little brown over the years doing that.  I guess the general consensus is that it isn't worth the time and trouble to get into it too far in an attempt to correct design flaws.  I kind of suspected this to be the case.  These receivers do work quite well on 80 and 40, AVC problems notwithstanding so I guess I'll keep them there. Glad I didn't get rid of my 75A-4.  DX-60B audio mods are in progress as we speak.  They should make a nice pair.  73 Doug.

[W2JBL]

don't convert that HR10 to a wheel chock just yet- they ain't all that bad. i got one (to relive my johnny novice days!) a couple years ago. it was a cosmetic 10 and an electronic 2. must have been built by a guy with an air chisel and a blowtorch. anyway, during recapping i paid close attention to lead length of the bypass caps, ground leads here and there, and lead dress. it turned out to be about the way i remember dad's was after he built his in ' 66. pretty good on 20, tolerable on 15 and a bit wimpy on 10 (dig that groovy drift on SSB!). it's still better than my 1938 S-19R on 10. basic audio mods helped a little too. maybe you can't polish a turd, but you can it least buff it to a dull luster!
XA

[Tom W2ILA]

I still have my first Heathkit - an HR10B complete with the optional HRA-10-1 calibrator.
I built the thing with a 200watt soldering iron and it still works.  Its a Hi Hi FB OM rx for 80 and 40m.  Compared with every other rx it is a turd for sensitivity and selectivity.  But, under the right conditions its pretty fun to run with the DX60B. And actually, the audio pumped into a decent speaker is pretty good.
Let us know how it goes on the higher bands experiment.  

73
Tom
W2ILA

[W9LCE]

for the higher bands - yes - as I understand it is the LO feed.  From what I have read (and the schematic) - they simply feed the LO  output directly, and try to read the needed overtone to drive the mixer (6EA8).  I haven't started on mine yet, but I will try switching in a toroid and diode doublers for 15 and 10, and maybe 20 (steal a bandswitch section from somewhere - maybe throw a switch to access them instead) - see if that works.

[VE3LYX]

I awarded the HR10B the worlds worst shortwave receiver award a few years ago. You can't polish a turd comment says it all. Actually I also have a Mohican. I may have been a bit hasty giving the award to the HR10B.
don

[w1vtp]

Might this be helpful?  Scroll down until you see the "Deaf on 15 and 10 meter section"

http://k6jca.blogspot.com/2010/11/improving-heathkit-hr-10b-receiver.html

It seems that the local oscillator for the first mixer is running on the 2nd harmonic which might account for the loss of sensitivity

Al

[KB2WIG]

Well, he can always buy a S 38... That'll learn 'em gud.


klc

[WD8BIL]

Turns out you can polish a turd!


https://www.youtube.com/watch?v=yiJ9fy1qSFI

[N2DTS]

You have to wonder why Heathkit hosed so many things up in the design stage.
At best, you can say they work, and not very well.

What is the IF frequency?
From building some receivers, I know its easy to make a very good but simple receiver, and there were loads of good but simple receivers around, even table top AM receivers (all American 5) that were likely better performers.
Odd IF frequencies, poor filters, really poor audio stages, they seemed to be limited to parts and tubes no one else would use.