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Old 13th Aug 2018, 7:13 pm   #1
deliverance
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Default Hammarlund HQ-170 issues

Hi all . Recently I required a 170 in lovely condition but dead no life nothing . After removing the radio from its case I noticed someone had fitted a step down transformer 240 to 110 on the chassis on checking the wiring I noticed the live on the mains side was hanging on by a thread plus the wires from the step down were all rotten so I decided to remove it and connect the factory 110v transformer back to how it should be . Then I powered it up with my Variac valves lit and life just humming and noticed the 5U4G was far too hot so fitted a known good one .. Powered back up and signals heard when tuning around but only on the 7mhz - 300 band the others bands were dead.

Powered down and had a good look underneath and noticed a burnt out resistor R9 1K going to T1 on the schematic so I fitted a new one powered up the resistor blew virtually straight away .. On the schematic R9 taps off B+ some 200 odd volts DC through the 1K resistor straight to T1 . Then on one part of T1 through a cap then via a white wire to the band switch supplying voltage . I need to know what the voltage is at the white wire because I took a tap of 100 volts dc and with a flying lead from source to the band switch and as a result the radio works fine and I have had it on for a while the flying lead is cool to the touch .. I realize there are issues with T1 and need to remove it to investigate I just find it strange it's working well.

Thoughts gentleman.
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Old 13th Aug 2018, 7:35 pm   #2
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Default Re: Hammarlind hq-170 issues .

Can you post a portion of the circuit please.
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Old 13th Aug 2018, 7:46 pm   #3
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Default Re: Hammarlind hq-170 issues .

BAMA has the HQ 170 and the HQ170A, link to the HQ170:

http://bama.edebris.com/manuals/hammarlu/hq170/

I don't fully understand the second part of the OP's post.

Lawrence.
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Old 13th Aug 2018, 7:55 pm   #4
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Default Re: Hammarlind hq-170 issues .

Sorry for any confusion, I have tried to explain the best I can.
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Old 13th Aug 2018, 8:03 pm   #5
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Default Re: Hammarlind hq-170 issues .

So far as I can make out the voltage on S2F (front) should be approx. the same as the 1st mixers anode voltage which is given as 250 volts in the manual, C11 might be favourite for R9 burn up?

Lawrence.

Last edited by ms660; 13th Aug 2018 at 8:18 pm. Reason: addition
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Old 13th Aug 2018, 8:20 pm   #6
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Default Re: Hammarlind hq-170 issues .

Hi Lawrence .. Thanks for your reply the voltage to S2f should be around 250 v I see I have 100v going to it now and is working as I have stated but the top two bands are pretty deaf I jumped the gun there . I will check C11 thanks again .
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Old 13th Aug 2018, 8:29 pm   #7
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Default Re: Hammarlind hq-170 issues .

Quote:
Originally Posted by ms660 View Post
So far as I can make out the voltage on S2F (front) should be approx. the same as the 1st mixers anode voltage which is given as 250 volts in the manual, C11 might be favourite for R9 burn up?

Lawrence.
Agreed, but I don't understand what temporary mod the OP has done to stop R9 burning out. DC cannot go through a capacitor unless it's leaky or short circuit.

Quote:
Then on one part of T1 through a cap then via a white wire to the band switch supplying voltage
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Old 13th Aug 2018, 8:45 pm   #8
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Default Re: Hammarlind hq-170 issues .

Hi Graham. Thanks for your reply R9 is disconnected to T1 . I have taken a 100v dc feed from a valve via a flying lead to S2F on the band switch .
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Old 13th Aug 2018, 8:53 pm   #9
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Default Re: Hammarlind hq-170 issues .

Quote:
Originally Posted by deliverance View Post
Hi Graham. Thanks for your reply R9 is disconnected to T1 . I have taken a 100v dc feed from a valve via a flying lead to S2F on the band switch .
Would that be from the stabilizer valve?

Lawrence.
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Old 13th Aug 2018, 9:04 pm   #10
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Default Re: Hammarlind hq-170 issues .

Yes Lawrence ..
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Old 13th Aug 2018, 9:09 pm   #11
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Default Re: Hammarlind hq-170 issues .

100 volts might not be enough to cause high leakage current through a component but 250 volts might be.

Lawrence.
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Old 13th Aug 2018, 10:10 pm   #12
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Default Re: Hammarlind hq-170 issues .

Just to note if your trying to follow S2F (front) switching, the switch is shown in the schematic in the 160 meter band position, the next position is for the 80 meter band, for those two positions it shorts out the 3.035MHz IF's primary coil, for the rest of the band ranges it shorts out the 455kHz IF's primary coil.

S2F (rear) kills the 2.58MHz Xtal osc on the 160 and 80 meter bands as the Xtal osc is only needed for the other bands (triple conversion)

Lawrence.

Last edited by ms660; 13th Aug 2018 at 10:16 pm. Reason: addition
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Old 13th Aug 2018, 10:52 pm   #13
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Default Re: Hammarlind hq-170 issues .

Thanks for the information I will check the caps around T1 tomorrow and report back .
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Old 19th Aug 2018, 7:48 pm   #14
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Default Re: Hammarlund HQ-170 issues

Good news C11 was the culprit along with a mmf cap luckily T1 has survived . After changing some out of spec resistors the set works fine .. The next problem was the clock not working , as the set originally had a step down transformer fitted on the chassis a dropper resistor was fitted to drop the voltage to 110v . The clock takes its supply direct from mains in so when I converted it back to 110v it was only getting some 40odd volts with the dropper in place removed it clock works fine .. Thanks for your help with this guy's its appreciated ..
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