To cap or not to cap. That is the quesion (HRO-60)

[K6JEK]

I've finally started work on the HRO-60

The Elmenco paper caps are good, at least the ones I've tested so far. That's with my Heathkit cap checker, nothing fancy. It has condemned many a cap before but these it has pronounced Not Guilty.

This receiver is full of the Elmenco's and ceramics with not so many micas. Maybe the Elmencos are not paper after all but early poly caps. Anyway they aren't leaky.

I'm inclined to just leave them. Is there any reason I shouldn't?

Thanks

Jon

PS: Many resistors are bad -- very high

[KM1H]

Ive tested several on a Sprague TC-3 and later a TC-6A some years ago and they all look like paper caps when run at rated voltage. Not bad leakage but more than I like which is only going to get worse.
Unless you want to gamble its not exactly going to break th bank to replace them.

Then dissect one for a show and tell.

Whats the serial # and did you get a matching manual?

Carl
KM1H

[K6JEK]

Ive tested several on a Sprague TC-3 and later a TC-6A some years ago and they all look like paper caps when run at rated voltage. Not bad leakage but more than I like which is only going to get worse.
Unless you want to gamble its not exactly going to break th bank to replace them.

Then dissect one for a show and tell.

Whats the serial # and did you get a matching manual?

Carl
KM1H

Where is the serial number on these? Is it just the 0378 stamped on the back of the chassis?

It came with an original manual but I don't know if it's the matching manual. There is no annotation in the manual about the serial number. The receiver has changed hands enough times things could have gotten mixed up. The coil sets are not 0378 so that may be an indication right there.

[ke7trp]

The serial is on the back right under the hood.  Carl had me check mine. 

I would replace the paper caps. Its an easy radio to recap and you wont take any changes on leakage.  I would also do the electrolytics.  The audio electrolytics are near alot of heat. There is just no reason not to change them. They are only 50V and can be purchased very cheap.

I really like my HRO60. It is super super sensitive.  Tons of gain.  The only complaint I have is even with the filter OFF, the radio is vary narrow. It wont do hifi am. Its about 5 KC opened all the way up according to the graph in the manual.  I was so used to using the 8KC postion on the SP600 and wide on the R390, It was hard to get used to that.

C

[KM1H]

The chassis will have a 7 digit serial, the first three are the Engineering Run (ER) and the rest are the serial. The back cover of the manual will have an ER # as well as a date code.

[WD5JKO]

Hijack

The only complaint I have is even with the filter OFF, the radio is vary narrow. It wont do hifi am. Its about 5 KC opened all the way up according to the graph in the manual.  I was so used to using the 8KC postion on the SP600 and wide on the R390, It was hard to get used to that.

   I wonder if the HRO manual suggests stagger tuning the IF stages with a sweep generator, or just peak tuning? Would that SDR receiver you bought work down at the IF frequency?

End Hijack

Jim
WD5JKO

[ke7trp]

My sdr will not go down to 455. I tried to use my sig gen to stagger tune but got nowhere.  Can u outline how u would do this and with what gear? I can probaby borrow an hp gen that has a sweep.  The 60 is very sharp. I really miss the audio of the sx42

[KM1H]

The 60 was designed for battle conditions, get a 50, NC-183, NC-240D, NC-200, NC-101X, etc for barn door fidelity with PP audio. Hammar and Halli had some good models also.

[ke7trp]

True.  But if I can stretch it out wider why not?  The NC183D is very sharp also.  5 to 6 kc.

C

[WD5JKO]

My sdr will not go down to 455. I tried to use my sig gen to stagger tune but got nowhere.  Can u outline how u would do this and with what gear? I can probaby borrow an hp gen that has a sweep.  The 60 is very sharp. I really miss the audio of the sx42

Clark,

   If I had the equipment I'd use a spectrum analyzer with no more than 1 Khz resolution bandwidth along with a tracking generator. Otherwise the following reference does it the 1950's way:

http://www.jumpjet.info/wireless/books/1955a.pdf

http://www.antiqueradios.org/gazette/align.htm

http://www.hparchive.com/Boonton/BRC-The-Notebook-07.pdf

Jim,
WD5jKO

[ke7trp]

Thanks Jim. I scanned through the articles. I wil have to sit down and read them.  I have been running through this in my head all day.

If I use my Sig gen into the rig and then hook my audio gen to modulate the sig generator so I can sweep the freq manual would that work?

I have an Real time analyzer here.  I could hook that to the output of the 60 with a padder.  Then I could inject say 1K audio into the rig at 455(or the xtal freq) and then once they are peaked, lower Freq and stagger tune the IF slightly while watching the RTA output.  I am sure I can see the level of each Audio freq and the width right on the display as I range the AUDIO generator back and forth.

I did read an article online that stated you can simply move the Sig gen freq over exactly 2 KC, Then adjust the First Can for peak there.  Then move over 2KC the other side and adjust the second can there.    They said when you sweep the gain should be flat across with NO Dip.  The article said that if you do that, You should get up to 8KC with minimal loss in gain. 

That makes sense and seems very simple.  The way I have it now with all those cans Dead peaked, This thing is very narrow.  3 to 5 KC range.  It makes AM sound pretty bad and muffled.  This HRO 60 has so much gain I never run the RF gain past 7!  I can bring No antenna noise to S9 level and typical 75 meter Noise all the way up to 30DB over.  So if I lost some gain, I would not really care to be honest.

C

[KM1H]

Clark, 75 is obviously less crowded out your way as a battle conditions radio is almost mandatory at night out here. In fact unless an AM station is LOUD the work done to get a wide bandwidth is wasted and boosting the average talk power is more beneficial.

With excessive gain you should increase the cathode resistor in the 1st IF amp. I used a PC type trimpot wired across the socket which allows for aging tubes. Maybe a couple of 6SS7's would cool it down also.

Jim, I loved those old Boonton/HP articles. Now I know how to use the 245A voltage standard which has been gathering dust in the attic.

Carl

[ke7trp]

Thanks for posting carl.  75 is very very busy here.  In fact, there is no free area on the band from top to bottom during the peak evening hours.   

I thought it would be nice to open up the IF a bit, then I can still use the Xtal filters to sharpen up if I needed too.

When you get a moment, I need a plan of attach on fixing a loose Phasing control coupler.  It started slipping on the inside and not the knob.  I dont see any easy way to get to that coupler to tighten it. 

If you can give me some instruction on how to do this, I will put the rig on the bench again, fix the coupler and add the Cathode pot to knock her down a bit.

C

[KM1H]

There is no easy way, pull it out.

[ke7trp]

I thought about injecting some super glue with a needle.  I hate to do that but it would probably work.

C

[ke7trp]

Jim.  I tried the stagger tuning today here are the results:

With a Perfect IF alignment dead center the HRO 60 was:

4.5 KC wide using a 20DB break point for each side. 

I then took the sig gen off 4 kC down and adjusted the first two Coils in the IF chain. I did not peak them to max here, I backed them off a bit between peak and the original setting.

Then I took the gen up to 4kc and adjusted the last two coils.  Same here. I did not peak them, I just kicked them up to peak and backed off in the original direction a bit.

Here are the results:

8KC wide using the 20DB break point.

I cannot hear a difference using my ICom as a test transmitter.  The icom is narrow. On BC band the difference is amazing.

If I rock the sig gen back and forth over the pass band each side is exactly the same DB down and there are no peaks. 

I tested the number 1 postion here and found a sharp 4 KC bandwidth.   So now I have 8KC and 4 KC postions. 

Very pleased!   I will have to put it on the air tonight and see she works.  Very pleased with the results.

C

[K6JEK]

The chassis will have a 7 digit serial, the first three are the Engineering Run (ER) and the rest are the serial. The back cover of the manual will have an ER # as well as a date code.

The serial is 514 0078 so it's engineering run 514 serial 78. Can you tell if that's late or early?
The manual says SM-400-1259

Haven't done any re-capping yet except for the power supply filter caps can but did replace a dozen resistors which were more than 20% off, all high, most very high. The receiver came alive with the new resistors.

[KM1H]

December 1959 is fairly late and is what I expected with that mix of caps. The next stage was Mylar replacing high value paper and that continued to the last run in 68...or 65 for general sales.

Earlier manuals had an ER # but I dont know when they switched to the way yours is. Constant management and engineering changes over those years.